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Relationships and taxonomy of the killifish genus Rivulus (Cyprinodontiformes: Aplocheiloidei: Rivulidae) from the Brazilian Amazonas river basin, with notes on historical ecology.

Abstract

Relationships among species of Rivulus endemic to the Brazilian Amazonas river basin are evaluated through an analysis of morphological characters, including terminal taxa representative of all Rivulus lineages. Based on the present morphological phylogeny and previous molecular analyses, seven subgenera are recognized: Rivulus, Cynodonichthys, Anablepsoides, Benirivulus n. subgen., Laimosemion, Owiyeye n. subgen., and Melanorivulus n. subgen. Benirivulus is diagnosed by a unique colour pattern and includes a single species, R. beniensis, from the rio Madeira drainage; Owiyeye is diagnosed by the absence of dermosphenotic, a derived pattern of frontal squamation, and a colour pattern of the mandibular region, and includes species from the Amazonas and Orinoco river basins; Melanorivulus is diagnosed by an apomorphic morphology of preopercle, and derived colour patterns of male postorbital region and female unpaired fins, and includes species from southern Amazonian tributaries, Parana-Paraguay river system, and Parnaiba and Sao Francisco river basins. Eighteen species from the Amazonas river basin of Brazil are recognized as valid: R. urophthalmus, R. taeniatus, R. micropus, R. ornatus, R. beniensis, R. strigatus, and R. dibaphus, which are herein redescribed, and R. atratus, R. romeri, R. kirovskyi, R. uatuman, R. uakti, R. amanapira, R. tecminae, R. modestus, R. zygonectes, R. violaceus, and R. litteratus, described or redescribed recently. Field data indicate that species of different lineages included in the clade comprising Benirivulus, Laimosemion, Owiyeye, and Melanorivulus are found in different kinds of aquatic environments, suggesting a divergent evolution for habitat preference.

Resumo

As relacoes de parentesco entre especies de Rivulus endemicas da bacia amazonica brasileira sao avaliadas atraves de uma analise de caracteres morfologicos, incluindo taxons terminais representativos de todas as linhagens de Rivulus. Com base na presente filogenia morfologica e em analises moleculares anteriores, sete subgeneros sao reconhecidos: Rivulus, Cynodonichthys, Anablepsoides, Benirivulus n. subgen., Laimosemion, Owiyeye n. subgen., e Melanorivulus n. subgen. Benirivulus e diagnosticado por um padrao de colorido exclusivo e inclui uma unica especie, R. beniensis, da drenagem do rio Madeira; Owiyeye e diagnosticado pela ausencia de dermosfenotico, um padrao de escamacao frontal derivado e um padrao de colorido da regiao mandibular, e inclui especies das bacias dos rios Amazonas e Orinoco; Melanorivulus e diagnosticado pela morfologia apomorfica do pre-operculo e pelos padroes de colorido derivados de regiao pos-orbital de macho e de nadadeiras impares de femeas, e inclui especies dos tributarios amazonicos meridionais, do sistema de rios Parana-Paraguai, e bacias dos rios Paranaiba e Sao Francisco. Dezoito especies da bacia do rio Amazonas do Brasil sao reconhecidas como validas: R. urophthalmus, R. taeniatus, R. micropus, R. ornatus, R. beniensis, R. strigatus e R. dibaphus, que sao aqui redescritas, e R. atratus, R. romeri, R. kirovskyi, R. uatuman, R. uakti, sR. amanapira, R. tecminae, R. modestus, R. zygonectes, R. violaceus e R. litteratus, recentemente descritas ou redescritas. Dados de campo indicam que especies de distintas linhagens, incluidas no clado que compreende Benirivulus, Laimosemion, Owiyeye e Melanorivulus, sao encontradas em tipos deferentes de ambientes aquaticos, sugerindo uma evolucao divergente para preferencia de habitats.



Zusammenfassung

Die verwandtschaftlichen Beziehungen der Arten der Gattung Rivulus, die endemisch im Amazonasbecken vorkommen, werden anhand von morphologischen Merkmalen untersucht und die Taxa der verschiedenen Linien innerhalb der Gattung abschliessend bewertet. Auf der Grundlage der gegenwartig bekannten morphologisch begrundeten Abstammungsverhaltnisse und der vorhandenen genetischen Analysen lassen sich sieben Untergattungen unterscheiden: Rivulus, Cynodonichthys, Anablepsoides, Benirivulus n. subgen., Laimosemion, Owiyeye n. subgen. und Melanorivulus n. subgen. Benirivulus lasst sich durch die einmalige Farbung eindeutig erkennen und umfasst nur eine Art: R. beniensis vom Rio Madeira und seinem Einzugsgebiet. Owiyeye kann am Fehlen des "dermosphenotischen" Knochens, am sekundaren Muster der Frontalbeschuppung und am Farbmuster des Unterkieferbereichs bestimmt werden; zu dieser Untergattung zahlen Arten vom Amazonas- und vom Orinocobecken. Melanorivulus wird gekennzeichnet durch: apomorphe (evoaqua, lutiv neue) Gestaltung des Praoperculums, abgeleitete Farbmuster der Postorbital-Region bei Mannchen und unpaare Flossen bei Weibchen; Arten der sudlichen Nebenflusse des Amazonas, des Parana-Paraguay-Systems und der Parnaibaund Sao-Francisco-Flussbecken gehoren dazu. Achtzehn Arten des brasilianischen Amazonasbeckens werden als gultig anerkannt: R. urophthalmus, R. taeniatus, R. micropus, R. ornatus, R. beniensis, R. strigatus und R. dibaphus, die hiermit wiederbeschrieben wird, sowie R. atratus, R. romeri, R. kirovskyi, R. uatuman, R. uakti, R. amanapira, R. tecminae, R. modestus, R. zygonectes, R. violaceus und R. litteratus, die in letzter Zeit neu oder wiederbeschrieben wurden. Nach Freilandbeobachtungen kommen die Arten verschiedener Abstammungslinien der Klade mit Benirivulus, Laimosemion, Owiyeye und Melanorivulus in unterschiedlichen aquatischen Lebensraumen vor, sodass von einer divergenten Evolution gemass dem bevorzugten Habitat auszugehen ist.

Resume

Des affinites entre des especes de Rivulus endemiques du bassin bresilien de l'Amazone sont evaluees au moyen d'une analyse de caracteristiques morphologiques, incluant des taxons terminaux representatifs de tous les lignages de Rivulus. Sur base de la phylogenie morphologique actuelle et d'analyses moleculaires anterieures, sept sous-genres sont identifies: Rivulus, Cynodonichthys, Anablepsoides, Benirivulus n. subgen., Laimosemion, Owiyeye n. subgen. et Melanorivulus n. subgen. Benirivulus se distingue par un patron de coloration unique et comprend une seule espece, R. beniensis, du systeme du Rio Madeira; Owiyeye est distinct par l'absence de dermosphenotique, un patron derive d'ecailles frontales, et un patron de coloration de la region mandibulaire, et inclut des especes des bassins de l'Amazone et de l'Orenoque; Melanorivulus se distingue par une morphologie apomorphique du pre opercule, des patrons de colorations derives de la region postorbitale du male et des nageoires impaires de la femelle et compte des especes des tributaires sud de l'Amazone, du systeme du Parana-Paraguay, du bassin du Paranaiba et du Sao Francisco. Dix-huit especes du bassin bresilien de l'Amazone sont reconnues: R. urophthalmus, R. taeniatus, R. micropus, R. ornatus, R. beniensis, R. strigatus et R. dibaphus, qui sont redecrits ici, et R. atratus, R. romeri, R. kirovskyi, R. uatuman, R. uakti, R. amanapira, R. tecminae, R. modestus, R. zygonectes, R. violaceus et R. litteratus, decrits ou redecrits recemment. Des donnes de terrain revelent que des especes de differents lignages faisant partie du clade comprenant Benirivulus, Laimosemion, Owiyeye et Melanorivulus se trouvent dans diverses sortes d'environnements aquatiques, suggerant une evolution divergente en matiere de choix d'habitat.

Sommario

I rapporti di parentela tra le specie del genere Rivulus endemiche della regione amazzonica del Brasile sono stati valutati con un'analisi dei caratteri morfologici, includendo taxa rappresentativi di tutte linee evolutive di Rivulus. Sulla base di questa analisi filogenetica e di precedenti filogenesi molecolari sono riconosciuti sette sottogeneri: Rivulus, Cynodonichthys, Anablepsoides, Benirivulus n. subgen., Laimosemion, Owiyeye n. subgen. e Melanorivulus n. subgen. Benirivulus e diagnosticato dalla singolare colorazione e comprende una sola specie, R. beniensis, presente nel bacino idrografico del rio Madeira; Owiyeye e diagnosticato per l'assenza del dermosfenotico, per un modello derivato di disposizione delle squame frontali e per la colorazione della regione mandibolare, e include specie dei bacini del Rio delle Amazzoni e dell'Orinoco; Melanorivulus e diagnosticato da una morfologia apomorfica del preopercolo e una colorazione derivata della regione postorbitale del maschio e delle pinne impari delle femmine, e include specie diffuse nei tributari meridionali del Rio delle Amazzoni, e nei bacici del Parana-Paraguay, del Parnaiba e del Sao Francisco. Diciotto specie sono riconosciute come valide nel bacino amazzonico brasiliano: R. urophthalmus, R. taeniatus, R. micropus, R. ornatus, R. beniensis, R. strigatus e R. dibaphus, che sono qui ridescritte, e R. atratus, R. romeri, R. kirovskyi, R. uatuman, R. uakti, R. amanapira, R. tecminae, R. modestus, R. zygonectes, R. violaceus e R. litteratus, che sono state descritte o ridescritte recentemente. Dati di campionamento indicano che le specie delle diverse linee evolutive incluse nell'unita cladistica comprendente Benirivulus, Laimosemion, Owiyeye e Melanorivulus sono diffuse in varie tipologie di ambiente acquatico, suggerendo un'evoluzione divergente nella preferenza dell'habitat.

Introduction

Rivulus Poey, 1860 is the most geographically widespread and diversified genus of Neotropical aplocheiloid killifishes (e.g. Costa 2003a). It is also the most taxonomically problematic genus of Neotropical aplocheiloids, in spite of recent efforts to clarify the taxonomic status of included species, among which many are still poorly defined. Taxonomic problems are due to: great number of included species (over 100 nominal species) in a wide geographic range (from Mexico, about 20[degrees] N, to Argentina, about 30[degrees] S, including Caribbean islands), making it difficult to develop taxonomic studies encompassing comparative material from all regions; brief descriptions, often including only a few characters insufficient to diagnose taxa; bad preservation of type specimens; equivocal synonymies (e.g. Garman 1895); and, unknown data on colour patterns of live specimens in older descriptions.

Rivulus was erected to include a single species from Cuba, R. cylindraceus Poey, 1860 (Poey 1860). Since then, over 120 nominal species were incorporated into Rivulus, some subgenera were described, and some species groups were diagnosed (e.g. Hoedeman 1959; Huber 1992; Costa 1995a, 2003a). Some studies have been directed to the taxonomy of Rivulus in some regularly and recently explored zoogeographical areas, including: Central America (e.g. Bussing 1980; Etzel & Berkenkamp 1992; Berkenkamp & Etzel 1992 1993a, 1993b, 1995, 1997, 1999), Guianas (Hoedeman 1959; Huber 1979, 1991; Vermeulen & Isbrucker 2000), rio Orinoco basin (Thomerson et al. 1991a, 1991b, 1992; Lasso et al. 1992; Thomerson & Taphorn 1992, 1993), Peruvian Amazon (e.g. Fels & Huber 1985; Fels & de Rham 1982), and central and south-eastern Brazil (e.g. Seegers 1984; Costa 1989, 1991, 1995a, 2003c, 2004g, 2005a; Costa & Brasil 1991). However, species of Rivulus endemic to the Brazilian Amazon have received little attention, except for recent descriptions of new species from the rio Negro drainage and near localities (e.g. Costa 2003b, 2004c, 2004d, 2004e). Among species of Rivulus from the Brazilian Amazon are some of the oldest species names presently assigned to the genus, therefore making them important keys in solving taxonomic problems.

The only genus today considered to be a synonym of Rivulus is Cynodonichthys Meek, 1904, which was described to include C. tenuis Meek from Mexico (Meek 1904). Cynodonichthys has been placed in the synonymy of Rivulus since Regan (1907). Vomerivulus Fowler, 1944 was proposed as a new monotypic subgenus of Rivulus based on the possession of vomerine teeth in its type species, R. leucurus Fowler, 1944, from the rio Jurado, Colombia (Fowler 1944). However, possession of vomerine teeth is a plesiomorphic condition in rivulids, occurring in most aplocheiloids, including R. cylindraceus, the type species of Rivulus (e.g. Costa 1998a, 1998b).

Hoedeman (1959, 1961), based on combinations of morphological features such as presence of caudal spot, details of colour patterns, maximum adult size, frontal squamation pattern, and number of longitudinal scales, divided Rivulus into species groups. Huber (1992) adopted this classification, recognizing a total of 18 assemblages (i.e., superspecies), besides describing a new monotypic subgenus, Anablepsoides Huber, 1992, for R. atratus Garman, 1895. Subsequently, two Huber's superspecies were formally recognized as new subgenera, Oditichthys Huber, 1999 and Laimosemion Huber, 1999 (Huber 1999). Some species groups have been consistently supported both by osteological (Costa 1998a) and molecular data (Murphy & Collier 1996, Murphy et al. 1999, Hrbek & Larson 1999, Hrbek et al. 2004).

Since the first taxonomic revision of the species grouped into the cyprinodontiform assemblage today known as the Rivulidae by Garman (1895), until recent years (Parenti 1981), Rivulus was defined by a combination of plesiomorphic morphological features. In other words, Rivulus was diagnosed by the absence of the distinctive features (i.e., apomorphies) that diagnose the other rivulid genera (e.g. long fins in Pterolebias Garman, 1895, vs. short fins in Rivulus; numerous dorsal- and anal-fin rays in Cynolebias Steindachner, 1876, vs. few rays in Rivulus) (Garman 1895, Regan 1912, Myers 1927). In addition, Rivulus contained species living in perennial aquatic biotopes, whereas the remaining rivulids comprised species inhabiting seasonal pools.

Weitzman & Wourms (1967) suggested that rivulids were derived from a Rivulus-like ancestor. Parenti (1981), based on morphological characters, provided the first phylogenetic analysis of rivulids, in which Rivulus was considered a paraphyletic group with their nominal species included at least in two basal rivulid lineages. Among the five nominal species of Rivulus examined in Parenti's analysis, R. stellifer Thomerson & Turner, 1973 (transferred to Rachovia Myers by Costa 1998a) and R. hartii (Boulenger, 1890) were placed in an assemblage termed "Rivulus", that would be more closely related to all other rivulid genera (e.g. Cynolebias; Pterolebias; Trigonectes Myers, 1925) than to Rivulus, which would include the type species R. cylindraceus, and R. marmoratus Poey, 1880 (transferred to Kryptolebias Costa, 2004 by Costa 2004a) and R. tenuis (Meek, 1904), among the species analysed in this study. Consequently, Rivulus was considered to be the sister group to a clade including "Rivulus" and all other rivulids, which was diagnosed by an apomorphic cartilaginous interhyal (vs. ossified in Rivulus) and a derived number of pelvic-fin rays (seven in "Rivulus" and the remaining rivulids, vs. six in Rivulus). However, Parenti (1981) did not find synapomorphies corroborating the monophyly of Rivulus or of "Rivulus".

Costa (1990), in a phylogenetic analysis based on morphological and behavioural traits, confirmed the presence of an ossified interhyal in some species then placed in Rivulus, but demonstrated that the number of seven pelvic-fin rays is not informative to define a rivulid clade. Rivulus was considered to be a monophyletic group based on the morphology of the shoulder girdle and the neural prezygapophyses of caudal vertebrae. A similar general phylogenetic hypothesis among rivulid lineages was obtained by Murphy & Collier (1997) using mitochondrial genes of seven rivulid species, but monophyly of Rivulus was not properly tested since only two species of Rivulus were included in the analysis.

Costa (1998a), in a subsequent phylogenetic study of rivulids, including new taxa and re-evaluating previously described morphological and behavioural characters, noted that, in fact, R. cylindraceus, the type species of Rivulus, not available in the previous study, has a cartilaginous interhyal. Among the new characters analysed, Costa (1998a) found that species of Rivulus with an ossified interhyal, i.e. R. brasiliensis (Valenciennes, 1821), R. caudomarginatus Seegers, 1984, and R. ocellatus Hensel, 1868, all later transferred to Kryptolebias by Costa (2004a) also exhibit other putative plesiomorphic conditions, and thus monophyly of Rivulus was weakly supported. Subsequent molecular analyses (Murphy et al. 1999, Hrbek & Larson 1999, Hrbek et al. 2004) indicated Rivulus as a paraphyletic group, with different assemblages as successive sister groups to a clade including annual fish genera.

Costa (2004a) described Kryptolebias to include species previously placed in Rivulus with an osseous interhyal, among other morphological features. Kryptolebias was considered to be the sister group to a clade including Rivulus and all other rivulids (Costa 2004a, 2004b, 2004c), a hypothesis supported by molecular data (Vermeulen & Hrbek 2005).

Since the description of Kryptolebias and the consequent transference of some species of Rivulus to Kryptolebias, a re-evaluation of the generic placement of species maintained in Rivulus became necessary, as well as a reassessment of morphological characters employed to define subgroups of Rivulus. The objectives of the present study are: to test hypotheses of relationships among species of Rivulus from the Brazilian Amazon to other rivulids, based on morphological characters discussed and illustrated in previous studies (e.g. Costa 1990, 1998, 2004, 2005b); to diagnose and to update data on the taxonomy and distribution of species of Rivulus from the Brazilian Amazonas basin, providing redescriptions of poorly known species; to re-evaluate morphological diagnoses for nominal subgenera and to purpose a new classification in order to formally accommodate hypotheses derived from recent phylogenetic studies.

Material and methods

Material pertinent to the taxonomic study on Rivulus from the Brazilian Amazonas river basin is listed in the taxonomical accounts below. Data on material is given in the following order: catalogue number, number of specimens; country: major political division: locality; collectors, and date of collection. Acronyms for institutions are: ANSP, Academy of Natural Sciences, Philadelphia; BMNH, The Natural History Museum, London; CAS, California Academy of Sciences, San Francisco; CBF, Colleccion Boliviana de Fauna, Museo Nacional de Historia Natural, La Paz; FMNH, Field Museum of Natural History, Chicago; INPA, Instituto Nacional de Pesquisas da Amazonia, Manaus; MCNG, Museo de Ciencias Naturales de la Universidad Nacional Experimental de los Llanos Occidentales, Guanare; MCP, Museu de Ciencias e Tecnologia da Pontificia Universidade Catolica do Rio Grande do Sul, Porto Alegre; MCZ, Museum of Comparative Zoology, Cambridge; MHNC, Museo Nacional de Historia Natural, La Havana; MNRJ, Museu Nacional, Universidade Federal do Rio de Janeiro, Rio de Janeiro; MZUSP, Museu de Zoologia, Universidade de Sao Paulo, Sao Paulo; NMW, Naturhistorisches Museum Wien, Vienna; UFPB, Universidade Federal da Paraiba, Joao Pessoa; UFRJ, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro; UMMZ, University of Michigan, Museum of Zoology, Ann Arbor; UNT, Universidade Federal do Tocantins, Porto Nacional; USNM, National Museum of Natural History (former United States National Museum), Smithsonian Institution, Washington; ZFMK, Zoologisches Farschungsinstitut und Museum Alexander Koenig, Bonn; and, ZUEC, Departamento de Zoologia da Universidade Estadual de Campinas, Campinas. Geographic entities are presented by their regional names (e.g. rio or rio, igarape, lago), which are not capitalized following Portuguese and Spanish grammars; this practice is important to avoid English style and generalizations when translating South American localities, which become data inaccurate and may incur errors (see also Menezes & Weitzman 1990, and Reis 1997 for further justification for this widely employed practice). EPA, that appears as collectors of some material, means Expedicao Permanente da Amazonia, a cooperative project between MZUSP, INPA and Museu Paraense Emilio Goeldi, Belem; NEAMB means Nucleo de Estudos Ambientais da Universidade Federal do Tocantins. The remaining material of Aplocheiloidei taxa examined in the present study is listed in the Appendix 1.

Measurements and counts follow Costa (1995b). Measurements are presented as percentages of standard length (SL), except for those related to head morphology, expressed as percentages of head length. Fin-ray counts include all elements. Number of vertebrae, gill rakers, and caudal-fin rays were recorded only from cleared and stained specimens. The compound caudal centrum was counted as a single element. Osteological preparations were made according to Taylor & Van Dyke (1985). Terminology for frontal squamation (i.e. A-H) follows Hoedeman (1958); determination of frontal squamation patterns (i.e. D, E, F) is according to Hoedeman (1958) (i.e. frontal scale with all margins free), except S-pattern (i.e. a scale just posterior to snout with all margins free) which is according to Huber (1992). Terminology for cephalic neuromast series follows Costa (2001).

The phylogenetic analysis is according to the cladistic methodology applied to morphological characters (e.g. Kitching et al. 1998, Wiens 2000). Terminal taxa were species of Rivulus occurring in the Brazilian Amazonas basin, species of Rivulus representing all main lineages from all zoogeographic regions inserted in the geographic area of the genus, and species of rivulid genera representing lineages closely related to Rivulus according to recent phylogenetic studies (Costa 1998a, Murphy et al. 1999, Hrbek & Larson 1999): Aphyolebias boticarioi Costa, 2004, Gnatholebias hoignei (Thomerson, 1974), Micromoema xiphophora (Thomerson & Taphorn, 1992), Moema apurinan Costa, 2004, Neofundulus paraguayensis (Eigenmann & Kennedy, 1903), Pituna compacta (Myers, 1927), Rachovia maculipinnis (Radda, 1964), Rachovia stellifer, Renova oscari Thomerson & Taphorn, 1995, and Trigonectes rubromarginatus Costa, 1990. Four

levels of out-groups were included: Prorivulus auriferus Costa, Lima & Suzart, 2004, and Kryptolebias brasiliensis, representing the successive most basal lineages of the Rivulidae (Costa 2004a, 2004c); Scriptaphyosemion guignardi (Romand, 1981) of the Nothobranchidae, the sister group of Rivulidae (Murphy & Collier 1997, Costa 2004a); and, Aplocheilus panchax (Hamilton-Buchanan, 1822) of the Aplocheilidae, the sister group of Nothobranchidae plus Rivulidae (Murphy & Collier 1997, Costa 2004a).

Characters were obtained from previous phylogenetic studies (e.g. Parenti 1981; Costa 1990, 1998a, 2005b).Character states of multi-state characters were treated as ordered whenever possible. Boundaries between states of quantitative characters were taken from Costa (2005b), which were determined to accommodate the best estimate of range observed for each terminal species included in that category (i.e. character state). All characters and character states used in the phylogenetic analysis are listed and coded in the Appendix 2 and are organized in the data matrix of Appendix 3. Most parsimonious cladograms, consistency indices (CI) and retention indices (RI) were obtained using the algorithm mhennig*;bb* of the program Hennig86 (Farris 1988). TreeGardener 2.2.1 (Ramos 1996) was used for optimisation of character state changes in the strict consensus tree of most parsimonious cladograms, using ACCTRAN. Bootstrap analysis (Felsenstein 1985) was used to establish nodal support through the simple heuristic algorithm of PAUP 4.0 (Swoford 1998) with 1000 replicates.

Results

Phylogenetic analysis

The phylogenetic analysis is based on a re-examination of previously reported, discussed and illustrated morphological characters (e.g. Parenti 1981; Costa 1990, 1998a, 2005b), which are listed in the Appendix 2. Their distribution among taxa examined appears in the data matrix (Appendix 3).

Six most parsimonious cladograms were found (tree length = 364, CI = 0.42, RI = 0.72). They differ only in the position of R. igneus, (i.e., as sister to R. hartii or to R. amphoreus Huber, 1979), and R. uatuman Costa, 2004 (i.e., as sister to R. romeri Costa, 2003 or to R. kirovskyi Costa, 2004). The strict consensus tree (three length = 367, CI = 0.41, RI = 0.71) is illustrated in Fig. 1.

Taxonomic accounts

Rivulus is here formally divided into seven subgenera, which are supported both by morphological (the present analysis) and molecular data (e.g. Murphy et al. 1999, Hrbek & Larson 1999; see discussion below). Subgenera of Rivulus and species occurring in the Brazilian Amazonas basin are listed and diagnosed below. Diagnoses of subgenera are synapomorphies obtained from the above phylogenetic analysis; numbers in parentheses refer to characters states listed in Appendix 2.

Rivulus Poey, 1860

Rivulus Poey, 1860: 299 (type species: Rivulus cylindraceus Poey; type by monotypy).

Subgenus Rivulus Poey, 1860

Rivulus Poey, 1860: 299 (type species: Rivulus cylindraceus Poey; type by monotypy).

[FIGURE 1 OMITTED]

Diagnosis

Distinguished from all other congeners by the possession of the following apomorphic features: hypurals completely fused to form a single plate (45.3), about 60% of the anterior portion of the caudal fin covered by scales (82.2), four neuromasts on the anterior supraorbital series (85.1), and a dark metallic blue humeral blotch in male.

Included species

R. cylindraceus Poey, 1860, R. insulaepinorum De La Cruz & Dubitsky, 1976 and R. roloffi Roloff, 1938.

Distribution

Rivers basins of Cuba and Republica Dominicana.

Subgenus Cynodonichthys Meek, 1904

Cynodonichthys Meek, 1904: 98 (type species: Cynodonichthys tenuis Meek; type by original designation).

Vomerivulus Fowler, 1944: 244 (type species: Rivulus leucurus Fowler; type by original designation).

Oditichthys Huber, 1999: 49 (type species: Rivulus igneus Huber; type by original designation).

Diagnosis

Tentatively diagnosed by the presence of yellow stripes on dorsal and ventral margins of caudal fin in male (101.1, 102.1), a condition inconspicuous or absent in some members of Cynodonichthys (i.e. reversals), but also exhibited by some species of Owiyeye (i.e. homoplasies).

Included species

Rivulus amphoreus Huber, 1979, R. bahianus Huber, 1990, R. birkhahni Berkenkamp & Etzel, 1992, R. boehlkei Huber & Fels, 1985, R. brunneus Meek & Hildebrand, 1913, R. christinae Huber, 1992, R. chucunaque Breder, 1925, R. cryptocallus Seegers & Huber, 1981, R. deltaphilus Seegers, 1983, R. depressus Costa, 1991, R. derhami Fels & Huber, 1985, R. elegans Steindachner, 1880, R. elongatus Fels & de Rham, 1981, R. erberi Berkenkamp, 1989, R. frommi Berkenkamp & Etzel, 1993, R. fuscolineatus Bussing, 1980, R. glaucus Bussing, 1980, R. haraldsiolii Berkenkamp, 1984, R. hartii (Boulenger, 1890), R. hildebrandi Myers, 1927, R. holmiae Eigenmann, 1909, R. igneus Huber, 1991, R. immaculatus Thomerson, Nico & Taphorn, 1991, R. intermittens Fels & de Rham, 1981, R. iridescens Fels & de Rham, 1981, R. isthmensis Garman, 1895, R. janeiroensis Costa, 1991, R. jucundus Huber, 1992, R. kuelpmanni Berkenkamp & Etzel, 1993, R. lanceolatus Eigenmann, 1909, R. leucurus Fowler, 1944, R. limoncochae Hoedeman, 1962, R. luelingi Seegers, 1984, R. lungi Berkenkamp, 1984, R. magdalenae Eigenmann & Henn, 1916, R. mazaruni Myers, 1924, R. micropus (Steindachner), 1863, R. monikae Berkenkamp & Etzel, 1995, R. monticola Staeck & Schindler, 1997, R. montium Hildebrand, 1938, R. nudiventris Costa & Brasil, 1991, R. ophiomimus Huber, 1992, R. pacificus Huber, 1992, R. peruanus (Regan, 1903), R. rubripunctatus Bussing, 1980, R. rubrolineatus Fels & de Rham, 1981, R. santensis Kohler, 1906, R. siegfriedi Bussing, 1980, R. simplicis Costa, 2004, R. speciosus Fels & de Rham, 1981, R. stagnatus Eigenmann, 1909, R. sucubti Breder, 1925, R. taeniatus Fowler, 1945, R. tenuis (Meek, 1904), R. tessellatus Huber, 1992, R. uroflammeus Bussing, 1980, R. urophthalmus Gunther, 1866, R. villwocki Berkenkamp & Etzel, 2002, R. waimacui Eigenmann, 1909, R. wassmanni Berkenkamp & Etzel, 1999, R. weberi Huber, 1992, and R. xanthonotus Ahl, 1926.

Distribution

River basins of Mesoamerica (between Mexico and Panama, and southern Caribbean islands), and northern (Colombia, Venezuela, Guianas, Peru, Ecuador, Bolivia and northern Brazil) and eastern South America (coastal plains of south, south-eastern and north-eastern Brazil).

Rivulus urophthalmus Gunther, 1866 (Figs. 2-9; Table I)

Rivulus urophthalmus Gunther, 1866: 327 (type locality: Para [Belem, formerly often known as Para, northern Brazil]; lectotype: BMNH 1851.12.26, designated by Huber 1991:67; photograph of lectotype in Huber 1991: 72, fig. 7).

Rivulus poey Steindachner, 1876: 165 (type locality: canals in the city of Para [now Belem]; types unknown; neotype: UFRJ 6282, male, 34.9 mm SL; creek at 15 de agosto street, Icoaraci, Belem; collected by A. Sarraf & M. Mourao Jr., 24 Jul. 1996 [herein designated]).

Rivulus urophthalmus var. aurata Schreitmuller, 1928: 88 (Maharankao [correctly Maranhao], Brazil; type: not designated).

Material examined

Brazil: Estado do Para: UFRJ 6247, 18; stream in praia de Ariramba, ilha do Mosqueiro, Belem, 1[degrees]6'34.7"S 48[degrees]25'32.7"W; W. J. E. M. Costa, R. Paiva & D. Ramos, 21 Jun. 2004. UFRJ 6248, 11; stream in ilha do Mosqueiro, Belem, 1[degrees]9'27.4"S 48[degrees]20'55.4"W; W. J. E. M. Costa, R. Paiva & D. Ramos, 21 Jun. 2004. UFRJ 6254, 8; UFRJ 6261, 3; stream crossing the road PA-391, ilha do Mosqueiro, Belem, 1[degrees]8'59.5"S 48[degrees]21'27.9"W; W. J. E. M. Costa, R. Paiva & D. Ramos, 21 Jun. 2004. UFRJ 6255, 11; creek near the road PA-124, near Santa Luzia, 0[degrees]46'39.1"S 47[degrees]16'43.5"W; W. J. E. M. Costa, R. Paiva & D. Ramos, 19 Jun. 2004. UFRJ 6256, 5; pools near stream near the road PA-446, Primavera, 0[degrees]54'8.9"S 47[degrees]2'31.0"W; W.J.E.M. Costa, R. Paiva & D. Ramos, 18 Jun. 2004. UFRJ 6257, 9; swamp at Quatipuru, 0[degrees]52'12.4"S 47[degrees]0'23.6"W; W. J. E. M. Costa, R. Paiva & D. Ramos, 18 Jun. 2004. UFRJ 6258, 15; stream near the road PA-124, near Pindorama, Salinopolis, 0[degrees]42'28.1"S 47[degrees]18'5.6"W; W. J. E. M. Costa, R. Paiva & D. Ramos, 18 Jun. 2004. UFRJ 6259, 4; UFRJ 6290, 34; stream at forest edge, road PA-446, Primavera, 0[degrees]56'23.9"S 47[degrees]5'21.6"W; W. J. E. M. Costa, R. Paiva & D. Ramos, 19 Jun. 2004. UFRJ 4087, 9 (c & s); igarape Maguary, Belem; A. Sarraf & E. Nogueira, 1 Aug. 1996. UFRJ 3055, 6 (c & s); Primavera; A. Werner, May 1988. UFRJ 4082, 6; campus of Universidade Federal do Para, Belem; A. Sarraf & M. Mourao Jr., 30 Jul. 1996. UFRJ 4083, 4; creek at 15 de agosto street, Icoaraci, Belem; A. Sarraf & E. Nogueira, 1 Aug. 1996. UFRJ 4079, 5; igarape Maguary, Belem; A. Sarraf & M. Mourao Jr., 24 Jul. 1996. Estado do Tocantins: UFRJ 5149, 9; floodplains of left bank of rio Tocantins, about 1200 m from the river margin, SSE Sampaio, 5[degrees]23'00"S 47[degrees]51'41"W; G. C. Brasil, 8 Jun. 2000. UNT 553, 3; rio Brejao, road BR-153, Araguaina; E. L. Beerli & L. M. Lima, 22 Nov. 2003. UNT 554, 5; river at the road BR-153, between Filadelphia and Araguaina; E. L. Beerli, 2 Nov. 2003. Estado do Amapa: INPA 2244, 26 (3 c & s); stream below cachoeira Santo Antonio, rio Jari drainage; M. Jegu & J. Zuanon, 21 Jun. 1987. Estado do Maranhao: UFRJ 5152, 16; swamp about 500 m from the right margin of rio Tocantins, 5[degrees]12'33"S 48[degrees]27'59"W; G. C. Brasil, 8 Jun. 2000. UFRJ 6293, 4; Olho d'Agua das Cunhas; A. C. De Luca, C. G. C. Wenceslau & M. A. Santos, 7 Jul. 2003.

[FIGURE 2 OMITTED]

[FIGURE 3 OMITTED]

[FIGURE 4 OMITTED]

[FIGURE 5 OMITTED]

[FIGURE 6 OMITTED]

[FIGURE 7 OMITTED]

Diagnosis

Distinguished from all other congeners by the combination of the following features: anterior portion of trunk slightly deeper than wide, jaws short, snout blunt, tip of anal fin rounded in male, caudal fin rounded in male, pelvic-fin tip not reaching anus in male, dorsal-fin origin on vertical between base of last 3rd and 4th anal-fin rays, dorsal-fin rays 7-8, anal-fin rays 12-14, frontal squamation E-patterned, frontal scales arranged circularly, canal preopercular short and opened, contact organs absent, longitudinal series of scales 37-40, gill rakers of first branchial arch 1-2 + 8, red stripes on flank, jaws not distinctively pigmented, and round black spot on dorsal portion of caudal fin in female.

[FIGURE 8 OMITTED]

[FIGURE 9 OMITTED]

[FIGURE 10 OMITTED]

Description

Morphometric data appear in Table I. Largest specimen, a female 43.9 mm SL. Dorsal profile gently convex from snout to end of dorsal-fin base, approximately straight on caudal peduncle. Ventral profile slightly convex from lower jaw to end of anal-fin base, about straight on caudal peduncle. Body slender, subcylindrical anteriorly, slightly deeper than wide, to compressed posteriorly. Greatest body depth at vertical just in front to pelvic-fin base. Jaws short, snout blunt.

Tip of dorsal and anal fins rounded. Caudal fin rounded. Pectoral fin short and rounded, posterior margin reaching vertical at about 60% of length between pectoral-fin and pelvic-fin bases. Pelvic fin short and elliptical, tip not reaching anus. Pelvic-fin bases medially separated by short interspace. Dorsal-fin origin on vertical between base of 3rd and 4th last anal-fin rays, and between neural spines of 21st and 23rd vertebrae. Anal-fin origin between pleural ribs of 15th and 17th vertebrae. Dorsal-fin rays 7-8; anal-fin rays 12-14; caudal-fin rays 25-28; pectoral-fin rays 13; pelvic-fin rays 6.

Scales small, cycloid. Body and head entirely scaled, except anterior ventral surface of head. Body squamation extending over anterior 30 % of caudalfin base; no scales on dorsal- and anal-fin bases. Frontal squamation E-patterned; E-scales not overlapping medially; scales arranged in regular circular pattern around A-scale without exposed margins. Longitudinal series of scales 37-40; transverse series of scales 8; scale rows around caudal peduncle 16. Contact organs absent.

Cephalic neuromasts: supraorbital 3 + 3, parietal 1, anterior rostral 1, posterior rostral 1, infraorbital 1 + 1 + 11-15 + 1, preorbital 2-3, otic 1, post-otic 2, supratemporal 1, median opercular 1, ventral opercular 2, preopercular 2 + 4, mandibular 4 + 1, lateral mandibular 2-3.

Interhyal minute, cartilaginous. Rostral cartilage longer than wide, width about 80% length. Basihyal subtriangular, width about 65% length; basihyal cartilage about 10% basihyal length. Six branchiostegal rays. Second pharyngobranchial teeth 3-4. Gill rakers of first branchial arch 1-2 + 8. Vomerine teeth 5-6. Ventral process of posttemporal short. Total vertebrae 32-35.

Coloration in life: Male: Side of body metallic yellowish green to metallic purplish blue ventrally; eight longitudinal rows of red to reddish brown dots, often in close proximity, forming stripes; usually three, sometimes four or five rows of red dots crossing caudal peduncle and reaching caudal-fin base, remaining rows reaching vertical through anal-fin base; dark chromatophores concentrated on longitudinal zone between flank and dorsum; sometimes dark grey bars on flank anterior to caudal peduncle, when fish exposed to strong sunlight. Dorsum light brown. Venter white. Side of head metallic yellowish green to metallic purplish blue, sometimes dark grey when fish exposed to strong sunlight. Lower jaw light brown. Iris light yellowish to greenish brown. Dorsal fin pale yellow with brown dots on basal portion, often with bright yellow zone. Anal fin yellow, basal portion sometimes blue, often with brown or red dots. Caudal fin pale yellow, often with brown dots and dorsal and ventral bright yellow zones, sometimes dorsal and ventral margins bright orange. Paired fins yellowish hyaline.

Female: Side of body light brown, with eight longitudinal rows of reddish brown dots, often in close proximity, forming stripes, alternating with longitudinal rows of pale golden dots; dark chromatophores concentrated on longitudinal zone between flank and dorsum; sometimes dark grey bars on flank anterior to caudal peduncle, when fish exposed to strong sunlight. Dorsum light brown. Venter white. Side of head pale metallic yellowish green to metallic purplish blue, sometimes dark grey when fish exposed to strong sunlight. Lower jaw light brown. Iris light yellowish to greenish brown. Unpaired fins yellowish hyaline with brown dots; round black spot on dorsal portion of caudal fin usually reaching fin margin, anteriorly bordered by small, triangular pale yellow spot. Paired fins hyaline.

[FIGURE 11 OMITTED]

Distribution

Lower Amazon basin, including lower Xingu and Tocantins river basins, and adjacent coastal drainages to East, northern Brazil (Fig. 10).

Habitat

Shallow creeks at sunny places, sometimes in forest border, at depths of about 5-10 cm (Fig. 11).

Rivulus taeniatus Fowler, 1945 (Figs 12-16; Table I)

Rivulus taeniatus Fowler, 1945: 129 (type locality: Morelia, rio Caqueta drainage, Colombia; holotype: ANSP 71720, illustrated by Fowler 1945: 129).

Material examined

Brazil: Estado do Amazonas: UFRJ 6245, 23; UFRJ 6246, 4 (c & s); creek adjacent to rio Urubui, rio Urubu basin, Presidente Figueiredo, 2[degrees]2'43.9"S 60[degrees]1'43.2"W; W. J. E. M. Costa, R. Paiva & D. Ramos, 11 Jun. 2004. INPA 1847, 1; INPA 1848, 2; pool near igarape Acara, Reserva Ducke, Manaus; Rosa, 23 Mar. 1988. INPA 2367, 4; Belem dos Pal-mares, rio Solimoes, between Benjamin Constant and Sao Paulo de Olivenca; R. Silva, 1 May 1987. INPA 3905, 3; INPA 3906, 1; igarape Candiru, km 50 of the Manaus-Itacoatiara road; C. Pereira, 11 Jul. 1990. UFRJ 3931, 73; pool near igarape Acara, Reserva Ducke, Manaus; C. Figueiredo & C. Codeco, 21 Sep. 1996. Estado do Acre: ZUEC non catalogued, 4; Campus Cacimba; C. F. D. Haddad & J. R. Santos, 2 Jan. 1982. UFRJ 6291, 7; UFRJ 6292, 82; creek between Rio Branco and Senador Guiomard, rio Acre drainage; W. J. E. M. Costa et al., 12 Jun. 2003.

Diagnosis

Distinguished from all other congeners by the combination of the following features: anterior portion of trunk slightly deeper than wide, jaws short, snout blunt, tip of anal fin rounded in male, caudal fin rounded in male, pelvic-fin tip usually not reaching anus and never reaching the anterior portion of the anal-fin base in male, dorsal-fin origin on vertical between base of last 2nd and 3rd anal-fin rays, dorsal-fin rays 7-9, anal-fin rays 12-15, frontal squamation E-patterned, frontal scales arranged circularly, canal preopercular short and opened, contact organs on flank scales in male, longitudinal series of scales 38-40, gill rakers of first branchial arch 2 + 9, red stripes on flank, jaws not distinctively pigmented except by red tip of lower jaw, and round black spot on dorsal portion of caudal-fin in female.

[FIGURE 12 OMITTED]

Description

Morphometric data appear in Table I. Largest specimen, a male 61.1 mm SL. Dorsal profile gently convex from snout to end of dorsal-fin base, approximately straight on caudal peduncle. Ventral profile slightly convex from lower jaw to end of anal-fin base, about straight on caudal peduncle. Body slender, subcylindrical anteriorly, slightly deeper than wide, to compressed posteriorly. Greatest body depth at vertical just in front to pelvic-fin base. Jaws short, snout blunt.

Tip of dorsal and anal fins rounded. Caudal fin rounded. Pectoral fin short and rounded, posterior margin reaching vertical at about 60 % of length between pectoral- and pelvic-fin bases. Pelvic fin short and elliptical, often tip not reaching anus, sometimes on urogenital papilla in male. Pelvic-fin bases medially separated by short interspace. Dorsal-fin origin on vertical between base of last 2nd and 3rd anal-fin rays, and between neural spines of 21st and 23rd vertebrae. Anal-fin origin between pleural ribs of 15th and 16th vertebrae. Dorsal-fin rays 7-9; anal-fin rays 12-15; caudal-fin rays 27-28; pectoral-fin rays 13-14; pelvic-fin rays 7.

[FIGURE 13 OMITTED]

Scales small, cycloid. Body and head entirely scaled, except anterior ventral surface of head. Body squamation extending over anterior 30 % of caudal-fin base; no scales on dorsal and anal-fin bases. Frontal squamation E-patterned; E-scales not overlapping medially; scales arranged in regular circular pattern around A-scale without exposed margins. Longitudinal series of scales 38-40; transverse series of scales 8; scale rows around caudal peduncle 16-18. Contact organ on each scale of midventral ventral portion of flank in male.

Cephalic neuromasts: supraorbital 3 + 3, parietal 1, anterior rostral 1, posterior rostral 1, infraorbital 1 + 1 + 13-15 + 1, preorbital 2-3, otic 1, post-otic 2, supratemporal 1, median opercular 1, ventral opercular 2, preopercular 2 + 4, mandibular 3-4 + 1, lateral mandibular 2.

Interhyal minute, cartilaginous. Basihyal subtriangular, width about 55 % length; basihyal cartilage about 10 % basihyal length. Six branchiostegal rays. Second pharyngobranchial teeth 1. Gill rakers of first branchial arch 2 + 9. Vomerine teeth 1. Ventral process of posttemporal short. Total vertebrae 33-36.

Coloration in life: Male: Side of body metallic yellowish green to metallic purplish blue ventrally; 7-8 longitudinal rows of red to reddish brown dots, usually in close proximity, forming stripes; usually three, sometimes four or five rows of red dots crossing caudal peduncle and reaching caudal-fin base, remaining rows reaching vertical between dorsal and anal-fin bases; dark chromatophores concentrated on longitudinal zone between flank and dorsum. Dorsum light brown. Venter white. Side of head metallic yellowish green to metallic purplish blue, sometimes dark bluish grey when fish exposed to strong sunlight. Lower jaw light brown, often with red tip. Iris light yellowish to greenish brown. Dorsal fin pale light grey with subbasal oblique row brown spots, often forming stripe; distal portion pale yellow. Anal fin pale yellow, basal portion sometimes blue, often with dark grey margin. Caudal fin light grey, dorsal portion pale yellow. Paired fins yellowish hyaline.

[FIGURE 14 OMITTED]

[FIGURE 15 OMITTED]

[FIGURE 16 OMITTED]

Female: Side of body light brown, with eight longitudinal rows of dark red to reddish brown dots, sometimes in close proximity, forming stripes; dark chromatophores concentrated on longitudinal zone between flank and dorsum. Dorsum light brown. Venter white. Side of head pale metallic yellowish green to metallic purplish blue, sometimes dark bluish grey when fish exposed to strong sunlight. Lower jaw light brown. Iris light yellowish brown. Unpaired fins yellowish hyaline with faint brown dots; round black spot on dorsal portion of caudal fin reaching fin margin, anteriorly bordered by small, triangular pale yellow spot. Paired fins yellowish hyaline.

[FIGURE 17 OMITTED]

Distribution

Western and middle rio Amazonas basin (Fig. 10).

Habitat

Shallow creeks at sunny places, sometimes in forest border, at depths of about 5-10 cm (Fig. 17).

Rivulus micropus (Steindachner, 1863) (Fig. 18; Table I)

Fundulus micropus Steindachner, 1863: 184 (type locality: Rio Negro, Brazil; holotype: NMW 77762; photographs and X-ray of lectotype in Huber 1991: 67, fig. 2).

Rivulus compressus Henn, 1916: 111 (type locality: Manaos [now Manaus]; emended as igarape da Cachoeira Grande, 2 miles out of Manaos, near mouth of rio Negro by Eigenmann 1911; holotype: FMNH 57003, illustrated by Henn 1916: fig. 1).

Material examined

Brazil: Estado do Amazonas: UFRJ 6288, 2; creek at the road Manaus-Manacapuru, 3[degrees]13'51.2"S 60[degrees]32'37.5"W; W. J. E. M. Costa, R. Paiva & D. Ramos, 9 Jun. 2004. UFRJ 6289, 3; stream at the road Manacapuru-Novo Airao, lower rio Negro basin, 3[degrees]10'30.7"S 60[degrees]42'34.9"W; W. J. E. M. Costa, R. Paiva & D. Ramos, 9 Jun. 2004. MZUSP 38307, 13; MZUSP 38449, 2 (c & s); lago Buiucu, Ati-Parana, NW of Fonte Boa; EPA, 11-12 Oct. 1968. INPA 1837, 3 (1c & s); FUA, Manaus; J. Zuanon, J. Porto & E. N. S. Silva, 10 May 1988. INPA 2371, 2; Distrito Industrial, Manaus; J. Zuanon, 21 Nov. 1988.

[FIGURE 18 OMITTED]

Diagnosis

Distinguished from all other congeners by the combination of the following features: anterior portion of trunk slightly deeper than wide, jaws slightly elongated, snout pointed, tip of anal fin slightly pointed in male, caudal fin rounded in male, pelvic-fin tip reaching anterior portion of anal-fin base in male, dorsal-fin origin on vertical between base of penultimate and last anal-fin ray, dorsal-fin rays 7-9, anal-fin rays 13-15, frontal squamation E or D-patterned, frontal scales arranged circularly, canal preopercular short and opened, contact organs on flank scales in male, longitudinal series of scales 40-45, gill rakers of first branchial arch 2 + 10, pink stripes on flank, jaws not distinctively pigmented, and round black spot on dorsal portion of caudal fin in female.

Description

Morphometric data appear in Table I. Largest specimen, a male 42.8 mm SL. Dorsal profile gently convex from snout to end of dorsal-fin base, approximately straight on caudal peduncle. Ventral profile slightly convex from lower jaw to end of anal-fin base, about straight on caudal peduncle. Body slender, subcylindrical anteriorly, slightly deeper than wide, to compressed posteriorly. Greatest body depth at vertical just in front to pelvic-fin base. Jaws slightly elongated, snout pointed.

[FIGURE 19 OMITTED]

Tip of dorsal rounded; tip of anal fin slightly pointed in male, rounded in female. Caudal fin rounded. Pectoral fin short and rounded, posterior margin reaching vertical at about 80 % of distance between pectoral and pelvic-fin bases. Pelvic fin elliptical, tip reaching between urogenital papilla and base of 2nd anal-fin ray in male, and urogenital papilla in female. Pelvic-fin bases medially separated by short interspace. Dorsal-fin origin on vertical between base of penultimate and last anal-fin ray, and between neural spines of 24th and 25th vertebrae. Anal-fin origin between pleural ribs of 16th and 17th vertebrae. Dorsal-fin rays 7-9; anal-fin rays 13-15; caudal-fin rays 29-30; pectoral-fin rays 15; pelvic-fin rays 7-8.

Scales small, cycloid. Body and head entirely scaled, except anterior ventral surface of head. Body squamation extending over anterior 30-40 % of caudal-fin base; no scales on dorsal and anal-fin bases. Frontal squamation E or D-patterned; E-scales not overlapping medially; scales arranged in regular circular pattern around A-scale without exposed margins. Longitudinal series of scales 40-45; transverse series of scales 8; scale rows around caudal peduncle 16. Contact organ on each scale of midventral ventral portion of flank in male.

Cephalic neuromasts: supraorbital 3 + 3, parietal 1, anterior rostral 1, posterior rostral 1, infraorbital 1 + 16 + 1, preorbital 3, otic 1, post-otic 2, supratemporal 1, median opercular 1, ventral opercular 2, preopercular 2 + 4, mandibular 4 + 2, lateral mandibular 3.

Interhyal minute, cartilaginous. Basihyal subtriangular, width about 55% length; basihyal cartilage about 25% basihyal length. Six branchiostegal rays. Second pharyngobranchial teeth 3-4. Gill rakers of first branchial arch 2 + 10. Vomerine teeth 1. Ventral process of posttemporal long. Total vertebrae 35.

Coloration in life: Male: Side of body dark blue, with 8 narrow pink stripes, of which 3-5 reaching caudal-fin base; dark chromatophores concentrated on longitudinal zone between flank and dorsum. Dorsum light brown. Venter white. Side of head dark purplish blue. Jaws dark brown. Iris brown. Unpaired fins pale yellow with brown spots. Paired fins hyaline.

Female: Similar to male, but flank stripes darker, and round black spot on dorsal portion of caudal fin reaching fin margin, anteriorly bordered by small, triangular pale yellow spot.

Distribution

Middle rio Amazonas basin (Fig. 19).

Habitat

Margins of streams and lakes at sunny places, sometimes in forest border, at depths of about 10-50 cm (Fig. 20).

[FIGURE 20 OMITTED]

Subgenus Anablepsoides Huber, 1992

Anablepsoides Huber, 1992: 43 (type species: Rivulus atratus Garman; type by original designation).

Diagnosis

Distinguished from the remaining subgenera of Rivulus by the following apomorphic features: rounded rostral cartilage (15.0), external medial teeth of premaxilla and dentary laterally displaced (20.1), long, acuminate caudal fin (76.1, 77.3), frontal squamation S-patterned (80.4; also occurring in Owiyeye), oblique dark grey on flank in male when exposed to sunlight (93.3), and transverse stripe through chin (98.2; also occurring in Owiyeye).

Included species

Rivulus atratus Garman, 1895 and R. ornatus Garman, 1895.

Distribution

Amazonas river basin, in Brazil and Peru.

Rivulus ornatus Garman, 1895 (Fig. 21; Table I)

Rivulus ornatus Garman, 1895: 139 (type locality: Silva, Cudajas, Lago Aleixo, Lake Hyanuary [four distinct localities in the Brazilian Amazon, Estado do Amazonas: Silves, Codajas, lago Aleixo and parana do Janauari]; lectotype: MCZ 6266, designated by Huber 1992: 347).

Rivulus obscurus Garman, 1895: 140 (type locality: Lake Hyanuary [parana do Janauari, Estado do Amazonas, Brazil]; lectotype: MCZ 6853, designated by Huber 1992: 336).

[FIGURE 21 OMITTED]

Material examined

Brazil: Estado do Amazonas: MCZ 6854, 4 paralectotypes; parana do Janauari, 3[degrees]12'S 60[degrees]5'W; L. Agassiz, 27 Oct. 1865. MCZ 98664, 1 paralectotype of R. obscurus; same data as MCZ 6854. UFRJ 7499, 28; stream tributary to rio Sanasani, Silves; EPA, 7 Oct. 1967. INPA 3908, 3; igarape Candiru, km 50 of the road Manaus-Itacoatiara; C. Pereira, 11 Jul. 1990. Estado do Para: MZUSP 37208, 3; lago Jacare, rio Trombetas; EPA, 7 Nov. 1969. MZUSP 38440, 2 (c & s); rio Curuinapui; EPA, 26 Jan. 1968.

Diagnosis

Distinguished from all other congeners by the combination of the following features: anterior portion of trunk slightly wider than deep, jaws short, snout blunt, tip of anal fin rounded in male, caudal fin elliptical to acuminate in male, pelvic-fin tip reaching the anterior portion of the anal-fin base in male, dorsal-fin origin posterior to anal-fin base, dorsal-fin rays 5-7, anal-fin rays 9-11, frontal squamation S-patterned, contact organs absent, frontal scales arranged circularly, canal preopercular short and opened, longitudinal series of scales 29-32, gill rakers of first branchial arch 1 + 7, oblique rows of red dots on flank in male, transverse black bar through the chin, and no black spot on dorsal portion of caudal-fin.

[FIGURE 22 OMITTED]

Description

Morphometric data appear in Table I. Largest specimen, a male 21.1 mm SL. Dorsal profile gently convex from snout to end of dorsal-fin base, approximately straight on caudal peduncle. Ventral profile weakly convex from lower jaw to end of anal-fin base, about straight on caudal peduncle. Body slender, subcylindrical anteriorly, wider than deep, to compressed posteriorly. Greatest body depth at vertical just in front of pelvic-fin base. Jaws short, snout blunt.

Tip of dorsal and anal fins rounded. Caudal fin elliptical, often pointed in male. Pectoral fin rounded, posterior margin reaching vertical between pelvic-fin base and anus in male, and vertical just anterior to pelvic-fin base in female. Pelvic fin elliptical, tip reaching between urogenital papilla and base of 4th anal-fin ray in male, between urogenital papilla and anal-fin origin in female. Pelvic-fin bases medially separated by short interspace. Dorsal-fin origin on vertical just posterior to anal-fin base, between neural spines of 20th and 21st vertebrae. Anal-fin origin between pleural ribs of 13th and 14th vertebrae. Dorsal-fin rays 5-7; anal-fin rays 9-11; caudal-fin rays 24; pectoral-fin rays 12-13; pelvic-fin rays 7.

Scales small, cycloid. Body and head entirely scaled, except anterior ventral surface of head. Body squamation extending over anterior 20 % of caudal-fin base; no scales on dorsal and anal-fin bases. Frontal squamation S-patterned; E-scales not overlapping medially; scales arranged in regular circular pattern around A-scale without exposed margins. Longitudinal series of scales 29-32; transverse series of scales 7; scale rows around caudal peduncle 16. Contact organs absent.

Cephalic neuromasts: supraorbital 3 + 3, parietal 1, anterior rostral 1, posterior rostral 1, infraorbital 1 + 12 + 1, preorbital 2, otic 1, post-otic 1, supratemporal 1, median opercular 1, ventral opercular 2, preopercular 2 + 4, mandibular 3-4 + 1, lateral mandibular 3.

Interhyal minute, cartilaginous. Basihyal subtriangular, width about 50% length; basihyal cartilage about 10% basihyal length. Six branchiostegal rays. Second pharyngobranchial teeth 1-2. Gill rakers of first branchial arch 1 + 7. Vomerine teeth 1. Ventral process of posttemporal absent. Total vertebrae 29-30.

[FIGURE 23 OMITTED]

Coloration in life: Male: Side of body pale blue, usually with 8 narrow light brown vertical lines, overlapped by oblique rows of red dots; dark chromatophores concentrated on longitudinal zone between flank and dorsum. Dorsum light brown with transverse dark brown bars. Venter brown. Side of head and infraorbital region dark metallic blue with red dots. Jaws light brown; dark brown to black transverse bar just below lower jaw. Iris brown. Dorsal and anal fins pale yellow to pale blue, with red to reddish brown bars. Dorsal portion of caudal fin pale yellow to pale blue with dark red narrow bars, median portion dark brown, and ventral portion reddish orange. Pectoral fin hyaline. Pelvic fin pale yellow.

Female: Side of body light brown with 8 narrow brown vertical lines, and 5-7 oblique dark brown bars; dark chromatophores concentrated on longitudinal zone between flank and dorsum. Dorsum light brown with transverse brown bars. Venter light brown. Side and ventral portion of head brown. Jaws light brown; dark brown to black transverse bar just below lower jaw. Iris brown. Unpaired fins hyaline with transverse narrow dark brown bars. Paired fins hyaline.

Distribution

Middle rio Amazonas basin, Brazil (Fig. 22).

Habitat

Stagnant waters in sunny places near forest border, with dense aquatic vegetation, about 50-150 cm deep.

Rivulus atratus Garman, 1895

Rivulus atratus Garman, 1895: 140 (type locality: Jutahy [now Jutai, Estado do Amazonas, Brazil]; lectotype: MCZ 6318, designated by Huber 1992: 102).

Material examined

Brazil: Estado do Amazonas: MCZ 98675, 1 paralectotype; Jutai; Thayer Expedition, Sep. 1865. MZUSP 38310, 1; MZUSP 38449, 1 (c & s); rio Icapo, mouth of rio Jutai; EPA, 22 Oct. 1968. MZUSP 38494, 12; lago Miua, above Codajas; EPA, 25 Sep. 1968.

Diagnosis

Distinguished from all other congeners by the combination of the following features: anterior portion of trunk wider than deep, jaws short, snout blunt, tip of anal fin rounded in male, caudal fin elliptical to acuminate in male, pelvic-fin tip not reaching to urogenital papilla in male, dorsal-fin origin posterior to anal-fin base, dorsal-fin rays 5-6, anal-fin rays 8-10, frontal squamation S-patterned, frontal scales arranged circularly, canal preopercular short and opened, contact organs absent, longitudinal series of scales 32-34, gill rakers of first branchial arch 1 + 7, dark brown oblique bars on flank, transverse black bar through the chin, and no black spot on dorsal portion of caudal fin. Also distinguished from all other congeners in having venter dark brown to black and dark brown spots on pectoral fin.

Distribution

Middle rio Amazonas basin, Brazil and Peru (Fig. 23).

Habitat

Still waters close to river and lake margins.

Benirivulus, new subgenus

Type species: Rivulus beniensis Myers, 1927.

Diagnosis

Two autapomorphic conditions were found in Benirivulus, which are not present in other congeners: a colour pattern of anal fin, consisting of one or two subbasal rows of reddish brown close dots, sometimes forming stripes, and a broad dark grey distal zone on the dorsal fin (Fig. 24).

Etymology

The name Benirivulus is derived from Beni, an important Amazonian river, and rivulus, from the Latin meaning stream, in reference to the occurrence of the new taxon in streams of that river basin. Gender masculine.

Included species

Only R. beniensis, the type species of the subgenus.

Distribution

Madeira river drainage, Amazonas river basin, in Bolivia and Brazil.

Rivulus beniensis Myers, 1927 (Fig. 24; Table II)

Rivulus strigatus (non R. strigatus Regan); Pearson, 1925: 51 (misidentification).

Rivulus beniensis Myers, 1927b: 133 (type locality: Ivon, Rio Beni [lower rio Beni, just above confluence with rio Madre de Dios, Departamento de Beni], Bolivia; lectotype: USNM 86776, designated by Fels & Huber 1985: 35).

Rivulus beniensis lacustris Myers, 1927b: 133 (type locality: lagoons along shores of Lake Rogoagua [lago Rogoaguado, rio Yata basin, which drains into rio Mamore, immediately above confluence with rio Beni], Bolivia; lectotype: UMMZ 66396, designated by Fels & Huber 1985: 35).

[FIGURE 24 OMITTED]

Rivulus bolivianus Seegers, 1988: 172 (type locality: laguna Suarez, ca. 4 km SW Trinidad, rio Mamore, Bolivia; holotype: ZFMK 14602).

Material examined

Bolivia: Departamento de Beni: CBF 1886, 54; CBF 1873, 39; Espirito, Estacion Biologica Beni; J. Sarmiento, 23-24 Apr. 1987. Brazil: Estado de Rodonia: UFRJ 5884, 67; UFRJ 5885, 4 (c & s); swamp near road BR-364, between Mutum-Parana and Abuna, rio Madeira basin, 9[degrees]40'34.2"S 65[degrees]4'9.9"W; W. J. E. M. Costa, S. Lima & A. Pinto, 6 Jun. 2003. UFRJ 5881, 6; swamp close to rio Mamore, near Guajara-Mirim, 10[degrees]45'53.5"S 65[degrees]20'21.7"W; W. J. E. M. Costa, S. Lima & A. Pinto, 7 Jun. 2003. Estado de Mato Grosso: swamp at km 2 of the road between Vila Bela and Casal Vasco, near rio Guapore; W. J. E. M. Costa, M. I. Landim, R. D'Arrigo & C. Moreira, 29 Apr. 1996.

Diagnosis

Distinguished from all other congeners by the combination of the following features: anterior portion of trunk slightly deeper than wide, jaws short, snout blunt, tip of anal fin rounded in male, caudal fin rounded in male, pelvic-fin tip reaching the anterior portion of the anal-fin base in male, dorsal-fin origin on vertical between base of 9th and 10th anal-fin rays, dorsal-fin rays 7-8, anal-fin rays 11-13, frontal squamation E-patterned, frontal scales arranged circularly, canal preopercular short and opened, contact organs on flank scales in male, longitudinal series of scales 29-32, gill rakers of first branchial arch 1 + 7, longitudinal rows of reddish brown dots stripes on flank in male, jaws black, and round black spot on dorsal portion of caudal-fin in female.

Description

Morphometric data appear in Table II. Largest specimen, a female 28.8 mm SL. Dorsal profile gently convex from snout to end of dorsal-fin base, approximately straight on caudal peduncle. Ventral profile slightly convex from lower jaw to end of anal-fin base, about straight on caudal peduncle. Body slender, subcylindrical anteriorly, slightly deeper than wide, to compressed posteriorly. Greatest body depth at vertical just in front to pelvic-fin base. Jaws short, snout blunt.

Tip of dorsal and anal fins rounded. Caudal fin rounded. Pectoral fin rounded, posterior margin reaching vertical at about 80% length between pectoral-fin and pelvic-fin bases. Pelvic fin elliptical, tip reaching between urogenital papilla and anal-fin origin in male, between anus and urogenital papilla in female. Pelvic-fin bases medially separated by short interspace. Dorsal-fin origin on vertical between base of 9th and 10th anal-fin rays, and between neural spines of 19th and 21st vertebrae. Anal-fin origin between pleural ribs of 15th and 16th vertebrae. Dor-sal-fin rays 7-8; anal-fin rays 11-13; caudal-fin rays 23-26; pectoral-fin rays 13; pelvic-fin rays 6.

Scales small, cycloid. Body and head entirely scaled, except anterior ventral surface of head. Body squamation extending over anterior 25 % of caudal-fin base; no scales on dorsal and anal-fin bases. Frontal squamation E-patterned; E-scales not overlapping medially; scales arranged in regular circular pattern around A-scale without exposed margins. Longitudinal series of scales 29-32; transverse series of scales 7; scale rows around caudal peduncle 16. Contact organ on each scale of midventral portion of flank in male.

Cephalic neuromasts: supraorbital 3 + 3, parietal 1, anterior rostral 1, posterior rostral 1, infraorbital 1 + 12 + 1, preorbital 2, otic 1, post-otic 1, supratemporal 1, median opercular 1, ventral opercular 1, preopercular 2 + 4, mandibular 3 + 1, lateral mandibular 2.

Interhyal minute, cartilaginous. Basihyal subtriangular, width about 35 % length; basihyal cartilage about 30 % basihyal length. Six branchiostegal rays. Second pharyngobranchial teeth 2. Gill rakers of first branchial arch 1 + 7. Vomerine teeth 2. Ventral process of posttemporal absent. Total vertebrae 30-32.

Coloration in life: Male: Side of body metallic yellowish green; six longitudinal rows of reddish brown dots, of which often two or three rows with sparse dots or absent, middle row forming stripe; dark chromatophores concentrated on longitudinal zone between flank and dorsum, often forming short oblique dark brown bars when fish exposed to strong sunlight. Dorsum light brown. Venter white. Side of head metallic yellowish green with small dark brown spots. Lower jaw black. Iris light yellowish with black vertical stripe. Dorsal fin pale yellow with subbasal row of reddish brown dots and dark grey distal stripe. Anal fin light blue on basal portion and pale yellow on distal portion, with one or sometimes two subbasal rows of reddish brown dots and dark grey distal stripe. Caudal fin light grey. Paired fins hyaline, anterior margin of pelvic fin dark grey.

[FIGURE 25 OMITTED]

Female: Side of body with irregularly shaped brown blotches, forming longitudinal row of rounded light brown interspaces on ventral portion; sometimes almost inconspicuous rows of brown dots coalesced to brown blotches; dark chromatophores concentrated on longitudinal zone between flank and dorsum, often forming short oblique dark brown bars when fish exposed to strong sunlight. Dorsum light brown. Venter white. Side of head pale metallic yellowish green with small dark brown spots. Lower jaw black. Iris light yellowish with black vertical stripe. Dorsal fin hyaline with two subbasal rows of brown dots and grey distal stripe. Anal fin hyaline with two or three subbasal rows of brown dots and grey distal stripe. Caudal fin light grey; round black spot on dorsal portion of caudal fin reaching caudal-fin margin, anteriorly bordered by small, triangular pale yellow spot. Paired fins hyaline, anterior margin of pelvic fin grey.

Distribution

Rio Madeira basin, Bolivia and Brazil (Fig. 19).

Habitat

Stagnant waters in sunny places near forest border, with dense aquatic vegetation, about 50-150 cm deep (Fig. 25).

Subgenus Laimosemion Huber, 1999

Laimosemion Huber, 1999: 49 (type species: Rivulus geayi Vaillant; type by original designation).

Diagnosis

Distinguished from other rivulids by having bifid epipleural ribs (43.1).

Included species

Rivulus agilae Hoedeman, 1954, R. dibaphus Myers, 1927, R. breviceps Eigenmann, 1909, R. cladophorus Huber, 1991, R. corpulentus Thomerson & Taphorn, 1993, R. frenatus Eigenmann, 1912, R. geayi Vaillant, 1899, R. gransabanae Lasso, Taphorn & Thomerson, 1992, R. lyricauda Thomerson, Berkenkamp & Taphorn, 1991, R. nicoi Thomerson & Taphorn, 1992, R. strigatus Regan, 1912, R. torrenticola Vermeulen & Isbrucker, 2000, and R. xiphidius Huber, 1979.

Distribution

Orinoco river basin, Guiana rivers, eastern Amazonas river basin and adjacent coastal areas in Venezuela, Guiana, Suriname, Guyana and Brazil.

Rivulus strigatus Regan, 1912 (Figs. 26-28; Table II)

Rivulus strigatus Regan, 1912: 502 (type locality: Amazon [Belem, Para, Brazil]; holotype: BMNH 1912.8.30).

R. geayi (non R. geayi Vaillant); Huber 1991: 69-70 (equivocal synonymy).

Material examined

Brazil: Estado do Para: UFRJ 6249, 25; UFRJ 6250, 6; UFRJ 6251, 4 (c & s); stream at the road PA-446, Primavera, 0[degrees]57'57.3"S 47[degrees]8'46.8"W; W. J. E. M. Costa, R. Paiva & D. Ramos, 19 Jun. 2004. UFRJ 6262, 1; stream at ilha do Mosqueiro, road PA-391, Belem, 1[degrees]8'59.5"S 48[degrees]21'27.9"W; W. J. E. M. Costa, R. Paiva & D. Ramos, 21 Jun. 2004. UFRJ 4075, 16; UFRJ 4078, 11; igarape Maguary, Belem; A. Sarraf & E. Nogueira, 1 Aug. 1996. UFRJ 1820, 1 (c & s); Belem; M. Lacerda, 1990.

Diagnosis

Distinguished from all other congeners by the combination of the following features: anterior portion of trunk slightly deeper than wide, jaws short, snout blunt, tip of anal fin slightly pointed in male, caudal fin rounded in male, pelvic-fin tip reaching the anterior portion of the anal-fin base in male, dorsal-fin origin on vertical between base of 7th and 8th anal-fin rays, dorsal-fin rays 8-9, anal-fin rays 11-13, frontal squamation F-patterned, frontal scales arranged circularly, canal preopercular short and opened, contact organs on flank scales in male, longitudinal series of scales 30-32, gill rakers of first branchial arch 1 + 7, longitudinal rows of red spots on anterior portion of flank and red chevron-like oblique bars on posterior portion of flank in male, jaws black, and no black spot on dorsal portion of caudal-fin.

Description

Morphometric data appear in Table II. Largest specimen, a male 26.5 mm SL. Dorsal profile slightly convex from snout to end of dorsal-fin base, approximately straight on caudal peduncle. Ventral profile weakly convex from lower jaw to end of anal-fin base, about straight on caudal peduncle. Body slender, subcylindrical anteriorly, slightly deeper than wide, to compressed posteriorly. Greatest body depth at vertical just in front to pelvic-fin base. Jaws short, snout blunt.

Tip of dorsal and anal fins slightly pointed in male, rounded in female. Caudal fin rounded. Pectoral fin rounded, posterior margin reaching vertical at about 75 % length between pectoral-fin and pelvic-fin bases. Pelvic-fin elliptical, tip reaching between base of 1st and 2nd anal-fin rays in male, between urogenital papilla and base of 1st anal-fin ray in female. Pelvic-fin bases medially in contact. Dorsal-fin ori-gin on vertical between base of 7th and 8th anal-fin rays, and between neural spines of 18th and 19th vertebrae. Anal-fin origin between pleural ribs of 14th and 15th vertebrae. Dorsal-fin rays 8-9; anal-fin rays 11-13; caudal-fin rays 28; pectoral-fin rays 14-15; pelvic-fin rays 6.

[FIGURE 26 OMITTED]

[FIGURE 27 OMITTED]

[FIGURE 28 OMITTED]

Scales small, cycloid. Body and head entirely scaled, except anterior ventral surface of head. Body squamation extending over anterior 25 % of caudal-fin base; no scales on dorsal- and anal-fin bases. Frontal squamation F-patterned; E-scales not overlapping medially; scales arranged in regular circular pattern around A-scale without exposed margins. Longitudinal series of scales 30-32; transverse series of scales 7; scale rows around caudal peduncle 16. Contact organ on each scale of midventral portion of flank in male.

Cephalic neuromasts: supraorbital 3 + 3, parietal 1, anterior rostral 1, posterior rostral 1, infraorbital 1 + 12-13 + 1, preorbital 2, otic 1, post-otic 1, supratemporal 1, median opercular 1, ventral opercular 2, preopercular 2 + 4, mandibular 3 + 1, lateral mandibular 2-3.

[FIGURE 29 OMITTED]

Interhyal minute, cartilaginous. Basihyal subtriangular, width about 50 % length; basihyal cartilage about 25 % basihyal length. Six branchiostegal rays. Second pharyngobranchial teeth absent. Gill rakers of first branchial arch 1 + 7. Vomerine teeth absent. Ventral process of posttemporal absent. Total vertebrae 30-31.

Coloration in life: Male: Side of body metallic blue or greenish blue; four to five longitudinal rows of red dots on anterior half of flank, and red chevronlike oblique bars with vertex anteriorly directed on posterior half of flank; dark blue humeral blotch. Dorsum light brown. Venter white. Side of head metallic greenish blue with small red spots; infraorbital region yellow. Jaws black. Iris brown, anterior and posterior portion green. Dorsal fin light blue with red bars on basal and posterior zones, red on anterior and distal portions; sometimes pale yellow anterior margin. Anal fin light blue with grey dots on basal and posterior portions; narrow dark reddish grey distal stripe. Upper two-thirds of caudal fin light red with transverse rows of small blue spots, lower third greenish blue; narrow dark reddish grey ventral stripe. Pectoral fin hyaline. Pelvic fin light blue with dark reddish grey anterior margin.

Female: Side of body light grey with small dark purplish brown spots arranged both in overlapped longitudinal and oblique rows; dark grey humeral blotch; dark chromatophores concentrated on longitudinal zone between flank and dorsum, often forming short transverse dark brown bars when fish exposed to strong sunlight. Dorsum light brown. Venter white. Side of head pale blue with small dark brown spots; infraorbital region pale yellow. Jaws black. Iris brown. Dorsal fin pale yellow on basal and posterior portions, light purplish grey on distal and anterior portions. Anal fin pale yellow to pale pink, basal portion light blue; distal margin dark grey. Caudal fin pale yellow with dark brown bars on upper two-thirds of fin. Pectoral fin hyaline. Pelvic fin pale yellow with dark grey anterior margin.

Distribution

River basins close to the right bank of rio Amazonas mouth (Fig. 19).

Habitat

Margins of clear water streams with moderate current, sand bottom, at depth of about 20-40 cm (Fig. 29).

Rivulus dibaphus Myers, 1927 (Figs 30-32; Table II)

Rivulus dibaphus Myers, 1927: 121 (type locality: Igarape do Ajamuri, Lower Amazon [corrected by S. O. Kullander in Huber 1991: 70 as Ajamuri or Agamuri, a beach in Lago Grande at mouth of rio Maicuru, just east of Santarem, Para, Brazil]; lectotype: CAS 44214, designated by Huber 1992: 184).

R. geayi (non R. geayi Vaillant); Huber, 1991: 69-70 (equivocal synonymy).

Material examined

Brazil: Estado do Para: CAS 44214, lectotype; CAS 44215, 6; Igarape do Ajamuri, Santarem; C. Ternetz, Jul. 1924. UFRJ 6283, 10; UFRJ 6284, 6 (c & s); UFRJ 6285, 4; stream 5 km S of Alter do Chao, Santarem, 2[degrees]33'1.3"S 54[degrees]57'21.1"W; W. J. E. M. Costa, R. Paiva & D. Almeida, 14 Jun. 2004. UFRJ 6286, 2; stream tributary to rio Tapajos, Porto Novo, Belterra, 2[degrees]37'45.9"S 54[degrees]58'41.7"W; W. J. E. M. Costa, R. Paiva & D. Almeida, 14 Jun. 2004. UFRJ 6286, 7; stream tributary to rio Tapajos, near Porto Novo, Belterra, 2[degrees]37'54.0"S 54[degrees]58'19.6"W; W. J. E. M. Costa, R. Paiva & D. Almeida, 14 Jun. 2004. INPA 2370, 8 (1 c & s); igarape do Patenos, rio Trombetas basin; J. Zuanon & E. Ferreira, 2 Dec. 1988.

[FIGURE 30 OMITTED]

[FIGURE 31 OMITTED]

[FIGURE 32 OMITTED]

Diagnosis

Distinguished from all other congeners by the combination of the following features: anterior portion of trunk slightly deeper than wide, jaws short, snout blunt, tip of anal fin slightly pointed in male, caudal fin subtruncate in male, pelvic-fin tip reaching the anterior portion of the anal-fin base in male, dorsal-fin origin on vertical between base of 7th and 8th anal-fin rays, dorsal-fin rays 9-10, anal-fin rays 12-13, frontal squamation E-patterned, frontal scales arranged circularly, canal preopercular short and opened, contact organs on flank scales in male, longitudinal series of scales 30-32, gill rakers of first branchial arch 1 + 9, longitudinal rows of red spots on anterior portion of flank and red chevron-like oblique bars on posterior portion of flank in male, jaws black, and no black spot on dorsal portion of caudal-fin.

Description

Morphometric data appear in Table II. Largest specimen, a male 26.5 mm SL. Dorsal profile slightly convex from snout to end of dorsal-fin base, approximately straight on caudal peduncle. Ventral profile weakly convex from lower jaw to end of anal-fin base, about straight on caudal peduncle. Body slender, subcylindrical anteriorly, slightly deeper than wide, to compressed posteriorly. Greatest body depth at vertical just in front to pelvic-fin base. Jaws short, snout blunt.

Tip of dorsal and anal fins slightly pointed in male, rounded in female. Caudal fin subtruncate in male, rounded in female. Pectoral fin rounded, posterior margin reaching vertical at about 75-90 % length between pectoral-fin and pelvic-fin bases. Pelvic fin elliptical, tip reaching between base of 2nd and 3rd anal-fin rays in male, between urogenital papilla and base of 2nd anal-fin ray in female. Pelvic-fin bases medially in contact. Dorsal-fin origin on vertical between base of 7th and 8th anal-fin rays, and between neural spines of 16th and 18th vertebrae. Anal-fin origin between pleural ribs of 13th and 14th vertebrae. Dorsal-fin rays 9-10; anal-fin rays 12-13; caudal-fin rays 28-31; pectoral-fin rays 14-15; pelvic-fin rays 6-7.

Scales small, cycloid. Body and head entirely scaled, except anterior ventral surface of head. Body squamation extending over anterior 30 % of caudal-fin base; no scales on dorsal and anal-fin bases. Frontal squamation E-patterned; E-scales not overlapping medially; scales arranged in regular circular pattern around A-scale without exposed margins. Longitudinal series of scales 30-32; transverse series of scales 7; scale rows around caudal peduncle 16. Contact organ on each scale of midventral portion of flank in male.

Cephalic neuromasts: supraorbital 3 + 3, parietal 1, anterior rostral 1, posterior rostral 1, infraorbital 1 + 12-16 + 1, preorbital 2-3, otic 1, post-otic 1, supratemporal 1, median opercular 1, ventral opercular 2, preopercular 2 + 4, mandibular 3 + 1, lateral mandibular 2-3.

Interhyal minute, cartilaginous. Basihyal subtriangular, width about 45% length; basihyal cartilage about 25% basihyal length. Six branchiostegal rays. Second pharyngobranchial teeth absent. Gill rakers of first branchial arch 1 + 9. Vomerine teeth absent. Ventral process of posttemporal absent. Total vertebrae 30-31.

[FIGURE 33 OMITTED]

Coloration in life: Male: Side of body metallic blue, bluish black on caudal peduncle; four to five longitudinal rows of red dots on anterior half of flank, and red chevron-like oblique bars with vertex anteriorly directed on posterior half of flank; dark blue humeral blotch. Dorsum light brown. Venter white. Side of head metallic greenish blue with small red spots; infraorbital region yellow. Jaws black. Iris brown, anterior and posterior portion green. Dorsal fin light blue with dark red reticulation. Anal fin light blue to pale yellow on distal portion, with grey dots or short bars on basal and posterior portions; narrow dark reddish grey distal stripe. Caudal fin pale blue with five or six dark red bars not extending to ventralmost portion of fin; usually black ventral stripe. Pectoral fin hyaline. Pelvic fin light blue with dark reddish grey anterior margin.

Female: Side of body light grey with small dark reddish brown spots arranged both in overlapped longitudinal and oblique rows, often alternating with bright greenish blue small spots; dark grey humeral blotch; dark chromatophores concentrated on longitudinal zone between flank and dorsum, often forming short transverse dark brown bars when fish exposed to strong sunlight. Dorsum light brown. Venter white. Side of head pale blue with small dark brown spots; infraorbital region pale yellow. Jaws black. Iris brown. Dorsal fin pale yellow with grey dots. Anal fin pale yellow, basal portion light blue; distal margin dark grey. Caudal fin pale yellow with dark brown dots on upper two thirds of fin. Pectoral fin hyaline. Pelvic fin pale yellow with dark grey anterior margin.

Distribution

Lower Tapajos and lower Trombetas river basins, and adjacent areas in eastern Amazonas river basin (Fig. 19).

Habitat

Margins of clear water streams with moderate current, sand bottom, at depths of about 20-40 cm (Fig. 33).

Owiyeye, new subgenus

Type species: Rivulus amanapira Costa, 2004.

Diagnosis

Distinguished from all other subgenera of Rivulus in having the following apomorphic features: absence of dermosphenotic (3.1), frontal scales transversely arranged (79.0) (Fig. 34A), frontal squamation S-patterned (80.4; also occurring in Anablepsoides) (Fig. 34A), and a transverse stripe through chin (98.2; also occurring in Anablepsoides).

Etymology

Owiyeye is the popular name used by Tucanos Indians from the upper rio Negro, Brazil, for R. amanapira (Costa 2004f). This name had already been reported by Wallace (2002) in notes made during his journey to the Amazon (1850-1852). Gender masculine.

Included species

Rivulus altivelis Huber, 1992, R. amanapira Costa, 2004, R. kirovskyi Costa, 2004, R. rectocaudatus Fels & de Rham, 1981, R. romeri Costa, 2003, R. tecminae Thomerson, Nico & Taphorn, 1992, R. uakti Costa, 2004 and R. uatuman Costa, 2004.

Distribution

Amazonas and upper Orinoco river basins, in Venezuela, Colombia, Brazil and Peru.

Rivulus romeri Costa, 2003

Rivulus romeri Costa, 2003a (type locality: brook tributary to Igarape Iauiari, about 0[degrees]14.31'N, 68[degrees]03.48[degrees]W, which is a tributary of the Uaupes river, itself a tributary of the Negro river, Amazonian basin, Amazonas, Brazil; holotype: MCP 29751).

[FIGURE 34 OMITTED]

Material examined

Brazil: Estado do Amazonas: MCP 29751, holotype; MCP 29752, 1 paratype; UFRJ 5447, 2 paratypes; UFRJ 5448, 4 paratypes (c & s); brook tributary to Igarape Iauiari, a tributary of the Uaupes river, itself a tributary of the Negro river, Amazonian basin; U. Romer, 21 Feb. 1995.

Diagnosis

Distinguished from all other congeners by the combination of the following features: anterior portion of trunk slightly deeper than wide, jaws short, snout blunt, tip of anal fin pointed in male, caudal fin rounded in male, pelvic-fin tip reaching urogenital papilla in male, dorsal-fin origin on vertical between base of 6th and 8th anal-fin rays, dorsal-fin rays 7-8, anal-fin rays 9-10, frontal squamation S-patterned, frontal scales arranged transversely, canal preopercular absent, contact organs absent, longitudinal series of scales 29-30, gill rakers of first branchial arch 1 + 6, longitudinal rows of red dots on flank in male, transverse dark brown bar through the chin, and no distinctive black spot on dorsal portion of caudal-fin.

Distribution

Upper rio Negro drainage (Fig. 10).

Habitat

Shallow pools within dense forest (U. Romer, pers. comm.).

Rivulus kirovskyi Costa, 2004

Rivulus kirovskyi Costa, 2004d: 10 (type locality: Reserva Ducke, temporary pools near igarape Acara, lower rio Negro drainage, rio Amazonas basin, about 3[degrees]0'S 60[degrees]30'W, Manaus, Estado do Amazonas, Brazil; holotype: UFRJ 5935 [transferred to INPA]).

Rivulus duckensis Hrbek, de Deus & Farias, 2004: 571 (Reserva Adolpho Ducke, rivulet emptying into Igarape Barro Branco, Manaus, Amazonas, Brazil, 2[degrees]53'S 59[degrees]58'W; holotype: INPA 21444).

Material examined

Brazil: Estado do Amazonas: UFRJ 5935, holotype; UFRJ 5936, 1 paratype (c & s); Reserva Ducke, temporary pools near igarape Acara, lower rio Negro drainage, rio Amazonas basin, Manaus; A. Kirovsky, 22 Feb. 1996. UFRJ 5937, 1 paratype, (c & s); UFRJ 5938, 1 paratype; same locality and collector, 25 Jan. 1996. UFRJ 5939, 2 paratypes; same locality and collector, 1 Feb. 1996. INPA 1850, 2 paratypes; same locality; J. Zuanon, 22 Nov. 1986.

Diagnosis

Distinguished from all other congeners by the combination of the following features: anterior portion of trunk slightly wider than deep, jaws short, snout blunt, tip of anal fin rounded in male, caudal fin rounded in male, pelvic-fin tip reaching anterior portion of anal-fin base in male, dorsal-fin origin on vertical between base of 8th and 9th anal-fin rays, dorsal-fin rays 6-7, anal-fin rays 9-10, frontal squamation S-patterned, frontal scales arranged transversely, canal preopercular absent, contact organs on flank scales in male, longitudinal series of scales 32, gill rakers of first branchial arch 1 + 7, transverse black bar through chin, and no black spot on dorsal portion of caudal-fin.

Distribution

Middle rio Amazonas basin (Fig. 23).

Habitat

Shallow pools in forest (A. Kirovsky, pers. comm.)

[FIGURE 35 OMITTED]

[FIGURE 36 OMITTED]

Rivulus uatuman Costa, 2004

Rivulus uatuman Costa, 2004e: 2 (type locality: Balbina, temporary pool near stream close to Rio Uatuma, rio Amazonas basin, 1[degrees]56'19.6"S 59[degrees]59'27.30.6"W, altitude 43 m, Estado do Amazonas, Brazil; holotype: UFRJ 6022).

Material examined

Brazil: Estado do Amazonas: UFRJ 6022, holotype; UFRJ 6023, 3 paratypes; UFRJ 6024, 2 paratypes (c & s); Balbina, temporary pool near stream close to Rio Uatuma, rio Amazonas basin altitude 43 m); W. J. E. M. Costa, R. Paiva and D. Ramos, 12 Jun. 2004.

Diagnosis

Distinguished from all other congeners by the combination of the following features: anterior portion of trunk slightly deeper than wide, jaws short, snout blunt, tip of anal fin rounded in male, caudal fin rounded in male, pelvic-fin tip reaching anterior portion of anal-fin base in male, dorsal-fin origin on vertical through base of the last anal-fin ray or slightly posterior to it, dorsal-fin rays 6-7, anal-fin rays 9-10, frontal squamation S-patterned, frontal scales arranged transversely, canal preopercular absent, contact organs on flank scales in male, longitudinal series of scales 31-33, gill rakers of first branchial arch 1 + 6, longitudinal rows of red dots on flank in male, transverse dark brown bar through the chin, and no distinctive black spot on dorsal portion of caudal fin. Also distinguished from all other species of Owiyeye by having unique colour patterns of unpaired fins in male, consisting of dorsal fin dark grey on basal portion and bright yellow on distal portion, and caudal fin dark grey with white posterior margin (Fig. 35).

Distribution

Middle rio Amazonas basin (Fig. 23).

Habitat

Isolated shallow temporary pools within forest, bottom litter, and water dark tea coloured (Fig. 36).

Rivulus uakti Costa, 2004

Rivulus uakti Costa, 2004f: 2 (type locality: Sao Gabriel da Cachoeira, stream near igarape Ia, km 9.4 of the road Sao Gabriel da Cachoeira to Cucui, upper rio Negro drainage, rio Amazonas basin, 0[degrees]3'51.1"S 66[degrees]59'46.9"W, altitude 99 m, Estado do Amazonas, Brazil; holotype: UFRJ 5925).

Material examined

Brazil: Estado do Amazonas: UFRJ 5925, holotype; UFRJ 5926, 36 paratypes; UFRJ 5927, 4 paratypes (c & s); MCP 34858, 2 paratypes; Sao Gabriel da Cachoeira, stream near igarape Ia, km 9.4 of the road Sao Gabriel da Cachoeira to Cucui, upper rio Negro drainage, rio Amazonas basin; W. J. E. M. Costa, S. Lima and L. Silva, 30 Aug. 2003. UFRJ 5928, 9; Sao Gabriel da Cachoeira, upper rio Negro drainage, rio Amazonas basin, stream tributary to igarape Miua, km 13.6 of the road Sao Gabriel da Cachoeira to Cucui, 0[degrees]2'58.7"S 66[degrees]57'48.6"W; W. J. E. M. Costa, S. Lima and L. Silva, 30 Aug. 2003.

[FIGURE 37 OMITTED]

[FIGURE 38 OMITTED]

[FIGURE 39 OMITTED]

Diagnosis

Distinguished from all other congeners by the combination of the following features: anterior portion of trunk slightly deeper than wide, jaws short, snout blunt, tip of anal fin slightly pointed in male, caudal fin rounded in male, pelvic-fin tip reaching middle of anal-fin base in male, dorsal-fin origin on vertical between base of 8th and 9th anal-fin rays, dorsal-fin rays 7-8, anal-fin rays 11-12, frontal squamation S-patterned, frontal scales arranged transversely, canal preopercular absent, contact organs on flank scales in male, longitudinal series of scales 32-33, gill rakers of first branchial arch 1 + 7-8, oblique rows of red dots on flank in male, transverse dark brown bar through the chin, and dark grey to black spot on dorsal portion of caudal-fin in both sexes. Also differs from all other congeners of the Owiyeye in possessing two unique colour patterns: dorsal fin with bright blue distal zone in male, and caudal spot forming a black bar posteriorly bordered by pale yellow bar in female (Figs 37-38).

Distribution

Upper rio Negro basin (Fig. 22).

Habitat

Moderately sunny places of shallow streams within the forest, sandy bottom and reddish hyaline water (Fig. 39).

Rivulus amanapira Costa, 2004

Rivulus amanapira Costa, 2004f: 7 (type locality: Sao Gabriel da Cachoeira, pools near igarape Palestina, Airport road, upper rio Negro drainage, rio Amazonas basin, 0[degrees]9'19.2"S 66[degrees]59'58.9"W, altitude 110 m, Estado do Amazonas, Brazil; holotype: UFRJ 5929).

[FIGURE 40 OMITTED]

[FIGURE 41 OMITTED]

Material examined

Brazil: Estado do Amazonas: UFRJ 5929, holotype; UFRJ 5930, 11 paratypes; UFRJ 5931, 3 paratypes (c & s); MCP 34859, 2 paratypes; Sao Gabriel da Cachoeira, pools near igarape Palestina, Airport road, upper rio Negro drainage; W. J. E. M. Costa, S. Lima and L. Silva, 30 Aug. 2003.

Diagnosis

Distinguished from all other congeners by the combination of the following features: anterior portion of trunk slightly deeper than wide, jaws short, snout blunt, tip of anal fin slightly pointed in male, caudal fin truncate in male, pelvic-fin tip reaching anterior portion of anal-fin base in male, dorsal-fin origin on vertical between base of 11th and 13th anal-fin rays, dorsal-fin rays 8, anal-fin rays 14-15, frontal squamation S-patterned, frontal scales arranged transversely, canal preopercular absent, contact organs on flank scales in male, longitudinal series of scales 48-49, gill rakers of first branchial arch 1 + 8, longitudinal rows of red dots on flank in male, transverse dark brown bar through the chin, and ovoid dark grey to black spot on dorsal portion of caudal fin in both sexes. Additionally distinguished from all other members of Owiyeye in having entire marginal region of caudal fin bright yellow in male (Fig. 40).

Distribution

Upper rio Negro drainage (Fig. 23).

Habitat notes

Small shallow temporary pools in the forest, about 0.5-2.0 m in diameter and about 15 cm deep (Fig. 41).

Rivulus tecminae Thomerson, Nico & Taphorn, 1992

Rivulus tecminae Thomerson, Nico & Taphorn, 1992: 290 (type locality: open savanna pools about 500 m from left bank, rio Guayapo, about 83 km above confluence with rio Sipapo, Orinoco basin, Amazonas Federal Territory, Venezuela, 4[degrees]16'N 67[degrees]20'W; holotype: MCNG 23886).

[FIGURE 42 OMITTED]

Material examined

Venezuela: Territorio Federal del Amazonas: MCNG 23886, holotype; MCNG 21369, 33 paratypes; open savanna pools about 500 m from left bank, rio Guayapo, about 83 km above confluence with rio Sipapo, Orinoco basin; L. Nico & E. Guayamare, 28 May 1989. Brazil: Estado do Amazonas: UFRJ 2085, 2; UFRJ 2095, 1 (c & s); Inambu, right bank of upper rio Negro; D. Teixeira, 26 Aug. 1991.

Diagnosis

Distinguished from all other congeners by the combination of the following features: anterior portion of trunk slightly deeper than wide, jaws short, snout blunt, tip of anal fin rounded in male, caudal fin truncate in male, pelvic-fin tip reaching middle of anal-fin base in male, dorsal-fin origin on vertical between base of 9th and 10th anal-fin rays, dorsal-fin rays 8-10, anal-fin rays 12-15, frontal squamation S-patterned, frontal scales arranged transversely, canal preopercular absent, contact organs on flank scales in male, longitudinal series of scales 37-41, gill rakers of first branchial arch 1 + 7, red stripes on flank, transverse black bar through the chin, and vertically elongated dark grey to black spot on dorsal portion of caudal-fin in both sexes.

Distribution

Upper Orinoco river basin, Venezuela, and upper Negro river, Brazil (Fig. 19).

Habitat

Temporary pools in savannas (D. Teixeira, pers. comm.).

Melanorivulus, new subgenus

Type species: Rivulus punctatus Boulenger, 1895.

Diagnosis

Distinguished from the remaining subgenera of Rivulus in having the following apomorphic features: dorsal portion of preopercle short and pointed (25.1) (Fig. 42), dorsal and anal fins slightly pointed in male (72.1, 73.1; also occurring in Laimosemion) (Fig. 43), two oblique bars on post-orbital region (97.1) (Fig. 43), melanophores concentrated on margins of unpaired and pelvic fins in female (111.1) (Fig. 44), and female with black spot on upper portion of caudal fin not close to fin margin, overlapping caudal fin bars (113.2) (Fig. 44). All included species except R. modestus have oblique chevron-like rows of red dots or bars on flank in males (90.2) (Fig. 43).

Etymology

From the Latin, melania (black pigmentation on the skin) and rivulus (stream), referring to the black margins of unpaired and pelvic fins, a condition unique among congeners. Gender masculine.

Included species

Rivulus apiamici Costa, 1989, R. cyanopterus Costa, 2005, R. dapazi Costa, 2005, R. decoratus Costa, 1989, R. egens Costa, 2005, R. litteratus Costa, 2005, R. modestus Costa, 1991, R. paracatuensis Costa, 2003, R. parnaibensis Costa, 2003, R. pictus Costa, 1989, R. pinima Costa, 1989, R. punctatus Boulenger, 1895, R. rossoi Costa, 2005, R. rutilicaudus Costa, 2005, R. scalaris Costa, 2005, R. violaceus Costa, 1991, R. vittatus Costa, 1989, and R. zygonectes Myers, 1927.

Distribution

Parana-Paraguay-Uruguay, upper Tapajos, upper and middle Xingu, upper and middle Tocantins, Sao Francisco and Parnaiba river basins, in central and north-eastern Brazil, south-eastern Bolivia, Paraguay and northern Argentina. Greatest diversification concentrated in the central Brazilian Plateau (Costa, 2005a).

Rivulus modestus Costa, 1991

Rivulus modestus Costa, 1991: 329 (type locality: rio Mutum, rio Tapajos basin, Mato Grosso, Brazil; holotype: MNRJ 11670).

Material examined

Brazil: Estado de Mato Grosso: MNRJ 11670, holotype; MNRJ 11671, 5 paratypes; UFRJ 2102, 6; UFRJ 2103, 5 (c & s); small stream tributary of rio Mutum, at crossing with road BR-364, 51 km from Vilhena, rio Juruena drainage, rio Tapajos basin; K. Tanizaki, M. T. Lacerda, S. O. Kullander & A. Hogerborn-Kullander, 16 Oct. 1989.

Diagnosis

Distinguished from all other congeners by the combination of the following features: anterior portion of trunk deeper than wide, jaws short, snout blunt, tip of anal fin slightly pointed in male, caudal fin rounded in male, pelvic-fin tip reaching anterior portion of anal-fin base in male, dorsal-fin origin on vertical between base of 8th and 9th anal-fin rays, dorsal-fin rays 10-11, anal-fin rays 13-14, frontal squamation F-patterned, frontal scales arranged circularly, canal preopercular absent, contact organs absent, longitudinal series of scales 31-33, gill rakers of first branchial arch 1 + 7-8, red marks of flank absent, lower jaw black, and round black spot on dorsal portion of caudal-fin in female.

Distribution

Upper rio Juruena drainage (Fig. 10).

Habitat notes

Shallow creeks with slow current, in moderately sunny region.

Rivulus zygonectes Myers, 1927

Rivulus zygonectes Myers, 1927: 127 (type locality: Vereda Extrema, into Cannabrava [now Cana Brava, at rio Tocantins left bank], Goyas [now Estado de Goias], Brazil; lectotype: CAS 76314, designated by Huber, 1992: 464).

Material examined

Brazil: Tocantins-Araguaia basin: Estado de Goias: CAS 76314, lectotype; Vereda Extrema into Cana Brava; C. Ternetz, 14 Jan. 1924. UFRJ 1575, 3; stream 15 km E of Aruana; W. J. E. M. Costa et al., 29 Aug. 1993. UFRJ 1748, 6; stream tributary to rio Verde, 30 km E of Sao Miguel do Araguaia; W. J. E. M. Costa et al., 25 Aug. 1993. UFRJ 1567, 5; stream 98 km W of Jussara; W. J. E. M. Costa et al., 30 Aug. 1993. UFRJ 1482, 22; UFRJ 2108, 2 (c & s); stream tributary to rio Verde, 32 km N of Sao Miguel do Araguaia; W. J. E. M. Costa et al., 25 Aug. 1993. MZUSP 35416, 20; MZUSP 38334, 55; pool in Aruana; W. J. E. M. Costa et al., 28 Jan. 1986. Estado do Tocantins: UFRJ 2106, 6; UFRJ 2107, 4 (c & s); stream 20 km S of Santa Rosa; W. J. E. M. Costa et al., 15 Feb. 1994. MZUSP 38375, 2; stream tributary to corrego Dona Francisquinha, Porto Nacional; W. J. E. M. Costa et al., 31 Jan. 1986. UFRJ 1712, 7; stream tributary to rio Verde, 50 km N of Sao Miguel do Araguaia; W. J. E. M. Costa et al., 25 Aug. 1993. UFRJ 1597, 2; stream 12 km N of Sandolandia; W. J. E. M. Costa et al., 27 Aug. 1993. MZUSP 37212, 28 (6 c & s); road between road BR-153 and Formoso do Araguaia, 29 km S of Gurupi; P. S. Santos-Filho, Jun. 1976. MZUSP 45223, 9; rio Agua Fria, road Araguacu-Barreira do Piqui, 27 km N of Araguacu; F. C. T. Lima, 21-26 Feb. 1993. UFRJ 1374, 13; shallow lagoon 2 km W of rio das Mortes at the road Agua Boa-Cocalinhos; W. J. E. M. Costa et al., 20 Feb. 1993. UNT 555, 5; river at the road BR-153 between Filadelphia and Araguaina; E. L. Beerli, 2 Nov. 2003. UNT 556, 3; rio Brejao, Araguaina; E. L. Beerli & L, M, Lima, 22 Nov. 2003. UNT 2045, 1; corrego Gorgulho, Porto Nacional; NEAMB, 14 Sep. 2001. UNT 2046, 1; corrego Gorgulho, Porto Nacional; NEAMB, 14 Sep. 2001. UNT 2047, 3; corrego Marimbondo, Tupirantins; NEAMB, 27 Oct. 2000. UNT 2048, 1; corrego Barreiro, Guarai; NEAMB, 20 Oct. 2000. UNT 2049, 2; corrego Gorgulho, Porto Nacional; NEAMB, 14 Sep. 2001. UNT 2050, 1; corrego Gorgulho, Porto Nacional; NEAMB, 14 Sep. 2001. UNT 2051, 1; corrego Lageado, Parana; NEAMB, 22 Mar. 1999. UNT 2052, 9; corrego Agua Suja, Tupirantins; NEAMB, 27 Oct. 2000. UFRJ 5150, 1; floodplains of left bank of rio Tocantins, about 1200 m from the river margin, SSE Sampaio, 5[degrees]23'00"S 47[degrees]51'41"W; G. C. Brasil, 8 Jun. 2000. Estado do Maranhao: UFRJ 5152, 16; swamp about 500 m from the right margin of rio Tocantins, 5[degrees]12'33"S 48[degrees]27'59"W; G. C. Brasil, 8 Jun. 2000. Rio Xingu basin, Estado de Mato Grosso: UFRJ 1386, 1; stream 67 km N of Paranatinga; W. J. E. M. Costa et al., 10 Feb. 1993. UFRJ 1173, 5; stream at the road BR-080, 9 km E of Sao Jose do Xingu; W. J. E. M. Costa et al., 16 Feb. 1993. UFRJ 1417, 1; stream at the road BR-080, 2 km E of Sao Jose do Xingu; W. J. E. M. Costa et al., 18 Feb. 1993. UFRJ 1389, 6; stream at the road BR-080, 41 km E of Sao Jose do Xingu; W. J. E. M. Costa et al., 17 Feb. 1993. UFRJ 1420, 6; stream at the road BR-080, 42 km E of Sao Jose do Xingu; W. J. E. M. Costa et al., 17 Feb. 1993. \UFRJ 1392, 7; stream at the road BR-080, 36 km E of Sao Jose do Xingu; W. J. E. M. Costa et al., 17 Feb. 1993. UFRJ 1357, 20; stream at the road Paranatinga-Canarana, 158 km of Paranatinga; W. J. E. M. Costa et al., 12 Feb. 1993. UFRJ 1414, 20; UFRJ 2109; stream at the road BR-080, 7 km E of rio Xingu margin; W. J. E. M. Costa et al., 16 Feb. 1993. UFRJ 6265, 1; stream near rio Xingu, Altamira; W. J. E. M. Costa et al., 16 Jun. 2004. Rio Tapajos basin, Estado de Mato Grosso: MZUSP 45304, 10; upper rio Preto, road Cuiaba-Santarem; N. Menezes et al., 24 Oct. 1992. MZUSP 45321, 2; stream tributary to rio Preto, road to Sao Francisco; N. Menezes et al., 24 Oct. 1992.

Diagnosis

Distinguished from all other congeners by the combination of the following features: anterior portion of trunk slightly deeper than wide, jaws short, snout blunt, tip of anal fin slightly pointed in male, caudal fin rounded in male, pelvic-fin tip reaching anterior portion of anal-fin base in male, dorsal-fin origin on vertical between base of 8th and 10th anal-fin rays, dorsal-fin rays 9-11, anal-fin rays 13-15, frontal squamation F-patterned, frontal scales arranged circularly, canal preopercular absent, contact organs absent, longitudinal series of scales 33-35, gill rakers of first branchial arch 1 + 7-8, oblique rows of red dots sometimes united forming chevron-like bars on flank in male, lower jaw black, and round black spot on dorsal portion of caudal fin in female.

Distribution

Tocantins, Araguaia, Xingu and Tapajos river basins (Fig. 22).

Habitat notes

Shallow creeks with slow current, in gallery forest of savanna-like region.

Rivulus violaceus Costa, 1991

Rivulus violaceus Costa, 1991: 331 (type locality: rio das Mortes, rio Araguaia-Tocantins basin, Mato Grosso, Brazil; holotype: MNRJ 11672).

Material examined

Brazil: Estado de Mato Grosso, rio das Mortes basin: MNRJ 11672, holotype; MNRJ 11673, 5 paratypes; UFRJ 2104, 20; rio das Mortes when crossed by BR-163 at km 313; K. Tanizaki, M. T. Lacerda, S. O. Kullander & A. Hogerborn-Kullander, 19 Oct. 1989. UFRJ 143, 16; UFRJ 2105, 7 (c & s); small stream tributary to rio Perdidos, close to BR-070, about 10 km W of Primavera do Leste; K. Tanizaki, M. T. Lacerda, S. O. Kullander & A. Hogerborn-Kullander, 19 Oct. 1989. UFRJ 1207, 4; rio Suspiro, 57 km S of Paranatinga; W. J. E. M. Costa, C. P. Bove, R. D. Cunha & C. Muratori, 9 Feb. 1993. UFRJ 4284, 13; idem; M. Britto, C. Moreira & R. Cunha, 28 Oct. 1996. UFRJ 4283, 3; stream at the road Primavera do Leste-Paranatinga; M. Britto, C. Moreira & R. Cunha, 28 Oct. 1996.

Diagnosis

Distinguished from all other congeners by the combination of the following features: anterior portion of trunk slightly deeper than wide, jaws short, snout blunt, tip of anal fin slightly pointed in male, caudal fin rounded in male, pelvic-fin tip reaching urogenital papilla in male, dorsal-fin origin on vertical between base of 8th and 9th anal-fin rays, dorsalfin rays 10-11, anal-fin rays 14-15, frontal squamation F-patterned, frontal scales arranged circularly, canal preopercular absent, contact organs absent, longitudinal series of scales 30-32, gill rakers of first branchial arch 1 + 7-8, oblique chevron-like red bars on flank in male, lower jaw black, and round black spot on dorsal portion of caudal fin in female.

Distribution

Upper rio das Mortes drainage (Fig. 10).

Habitat notes

Shallow creeks with slow current, in gallery forest of savanna-like region.

Rivulus litteratus Costa, 2005

Rivulus sp.: Lacerda, 1989: 25 (Ponte Branca, Rio Araguaia, central Brazil).

[FIGURE 43 OMITTED]

[FIGURE 44 OMITTED]

Rivulus pictus (non Costa): Costa et al., 2003: 143 (misidentification of specimens from Alto Araguaia).

Rivulus litteratus Costa, 2005a: 75 (type locality: Municipio de Alto Araguaia, Corrego do Sapo, upper Rio Araguaia basin, road MT-100, 31 km S of Alto Araguaia, 17[degrees]33'38.5"S 53[degrees]18'33.1"W, altitude 750 m, Estado de Mato Grosso, Brazil; holotype: UFRJ 5956).

Material examined

Brazil: Estado de Mato Grosso: Municipio de Alto Araguaia, upper rio Araguaia basin: UFRJ 5956, holotype; Municipio de Alto Araguaia, corrego do Sapo, upper rio Araguaia basin, road MT-100, 31 km S of Alto Araguaia; W. J. E. M. Costa, B. B. Costa and C. P. Bove, 14 Jan. 2004.

[FIGURE 45 OMITTED]

Diagnosis

Distinguished from all other congeners by the combination of the following features: anterior portion of trunk slightly deeper than wide, jaws short, snout blunt, tip of anal fin slightly pointed in male, caudal fin rounded in male, pelvic-fin tip reaching anterior portion of anal-fin base in male, dorsal-fin origin on vertical between base of 7th 8th l-fin rays, dorsal-fin rays 9-10, anal-fin rays 13-14, frontal squamation F-patterned, frontal scales arranged circularly, canal preopercular absent, contact organs absent, longitudinal series of scales 31-32, gill rakers of first branchial arch 1 + 7-8, overlapped red marks of variable shape on flank in male, lower jaw dark grey, and round black spot on dorsal portion of caudal-fin in female. Also distinguished from the remaining species of Melanorivulus by possessing a colour pattern consisting of red marks variable in shape and highly overlapped (Fig. 43).

Distribution

Upper rio Araguaia drainage (Fig. 23).

Habitat notes

Shallow creeks with slow current, in gallery forest of savanna-like region (Fig. 45).

Discussion

The present study confirms a weakly supported genus Rivulus containing clades corroborated both by morphological (e.g. Huber 1992, Costa 1998a, the present study) and molecular data (e.g. Murphy et al. 1999, Hrbek & Larson 1999), and recognized as subgenera. No unambiguous, apomorphic morphological condition was found to be shared by all species presently assigned to Rivulus and molecular studies indicate that Rivulus is a paraphyletic assemblage (Murphy et al. 1999, Hrbek & Larson 1999). However, a group comprising all species of Rivulus except the subgenus Rivulus is well supported by morphology, their members having a uniquely derived pattern of arrangement of rostral neuromasts (i.e. transversely placed), and a long neural prezygapophysis in caudal vertebrae as already discussed in former studies (e.g. Costa 1998a), also occurring in Kryptolebias.

The subgenus Rivulus, as herein defined, is also corroborated by a molecular analysis (Murphy et al. 1999: 295). In other molecular analyses, R. roloffi is considered to be more closely related to other nominal species of Rivulus than to R. cylindraceus (e.g. Hrbek & Larson 1999). As R. roloffi, which was not accurately examined in the present study (only examined at the field just after collection), have more than half caudal fin scaled and a dark green humeral spot, which constitute two synapomorphies of the subgenus Rivulus, R. roloffi is inserted in this subgenus.

Although weakly supported by morphological features, Cynodonichthys as proposed here is also corroborated by molecular data (Murphy et al. 1999: 295). However, some molecular analyses do not support monophyly of this assemblage (e.g. Hrbek & Larson 1999). Further analyses should be conducted in order to test the monophyly of this geographically widespread assemblage.

Three species of Cynodonichthys from the Brazilian Amazonas basin were found in collections examined in the present study: R. urophthalmus, R. taeniatus and R. micropus. A fourth species, R. xanthonotus, has been reported for the Brazilian Amazon. However, this species, which seems to be similar to R. urophthalmus, is only known from its poor original description (Ahl 1926), where the type locality is inaccurately described (i.e. "Amazon Strom"). Huber (1992) reported that types exhibit an uncommon posteriorly positioned dorsal fin, thus constituting a valid species. No specimen potentially identifiable as R. xanthonotus was examined in the present study.

Rivulus urophthalmus was found in an extensive region encompassing the lower Amazonas basin and tributaries, and adjacent coastal areas to East, including Maranhao, the type locality R. auratus. This latter species is therefore considered a synonym of R. urophthalmus, as already proposed by Huber (1992).

Rivulus poey was described by Steindachner (1876) based on specimens from Belem. The brief description includes characters congruent with R. urophthalmus, previously described from the same locality. As the types of R. poey are unknown, this highly probable synonymy cannot be confirmed. In order to solve this problem, a neotype from the city of Belem is herein designated for R. poey, becoming a clear synonym of R. urophthalmus, as already proposed by other authors (e.g. Garman 1895, Huber 1991).

A geographically widespread species of the central and western Brazilian Amazon is here tentatively identified as R. taeniatus, a species first described from the Colombian Amazon and still poorly known. However, the species collected in some distant points of the Brazilian Amazon also fits well with other nominal species from the Peruvian and Ecuadorian Amazon, such as R. rubrolineatus and R. limoncochae, which possibly are synonyms of R. taeniatus. These species have been distinguished mainly on the basis of the number of rows of red dots on the caudal peduncle (i.e. three or five) (e.g. Huber 1992). However, this character was variable within populations both of R. urophthalmus and R. taeniatus (see descriptions above).

Steindachner (1863) described R. micropus based upon a single specimen collected in the rio Negro, Brazilian Amazon. The identity of this species was obscure until publication of photos and new morphological data on the holotype (Huber 1991). Henn (1916) described a similar species, R. compressus, from Manaus, a city at the confluence of rio Negro and rio Solimoes, central Brazilian Amazon. At the beginning of the description of R. compressus, Henn (1916: 111) noted that: "This may be R. micropus Steidachner, but it seems to differ in the more forward position of the dorsal, the longer head, etc.". However, Huber (1992) examined types of both species and concluded that these diagnostic characters are similar in both nominal species. This synonymy follows Costa (2003b), supported by material collected in the type locality region, having pointed snout and posteriorly positioned dorsal fin as observed in holotypes of R. micropus (Huber, 1991: fig. 2) and R. compressus (Henn, 1916: fig. 1).

Anablepsoides was first proposed to include only R. atratus (Huber, 1992). However, morphological data (Costa 1998a, the present study) consistently corroborated a clade containing both R. atratus and R. ornatus. This hypothesis has not yet been tested by molecular analyses, since both included species were not simultaneously included in these studies (e.g. Murphy et al. 1999, Hrbek & Larson 1999).

Examination of types revealed that R. ornatus and R. obscurus, respectively, refer to the male and female of the same species, thus constituting synonyms (Costa 2003b). Rivulus ornatus has been identified as R. obscurus (e.g. Huber 1992), whereas an undescribed species from Peru has been misidentified as R. ornatus (e.g. Fels & de Rham 1982, Huber 1992). The specimen mentioned by Garman (1895: 139) under the description of R. ornatus, as possibly belonging to another species, is in fact a member of the poeciliid genus Fluviphylax Whitley (Costa 1996, Costa & Le Bail 1999).

Benirivulus is erected to R. beniensis, which does not fit with any other subgenus of Rivulus. The present phylogenetic hypothesis indicates that Benirivulus is the sister group to a clade including three subgenera, Laimosemion, Owiyeye, and Melanorivulus, each of them corroborated by both morphological and molecular data. The only species of Benirivulus, R. beniensis, was poorly known until now, and consequently was not included in molecular analyses. Myers (1927b) erected R. beniensis on the basis of specimens collected in the drainage of the Beni-Mamore drainage, rio Madeira basin, and previously misidentified by Pearson (1925) as R. strigatus. Based on putative minor differences in dorsal-fin origin position, Myers (1927b) recognized two subspecies from distinct localities, R. beniensis beniensis and R. beniensis lacustris. Seegers (1985) described R. bolivianus also from the rio Mamore drainage. Examination of material from distant localities along the rio Madeira basin, including the Mamore, Beni and Guapore river drainages, revealed that R. beniensis is a widespread species, indistinguishable from R. beniensis lacustris and R. bolivianus, thus confirming the synonymy proposed by Costa (2003b).

Huber (1999) erected Laimosemion to include species of the "R. geayi superspecies" as proposed by Huber (1992). Molecular studies (Murphy et al. 1999, Hrbek et al. 2004) corroborated monophyly of a group comprising species of the "R. geayi superspecies", "R. breviceps superspecies", and "R. frenatus superspecies", which is in accordance to the present study. Two species of Laimosemion are found in the Brazilian Amazonas river: R. strigatus and R. dibaphus.

Rivulus strigatus was described by Regan (1912) based on a single specimen donated by Arnold. This material was obtained from an aquarium fish shipment from the city of Para (now Belem, capital of Estado do Para) (Arnold 1913). Huber (1992) mentioned rio da Prata, a tributary of rio Jari, Para, Brazil, as the true type locality of R. strigatus, based on a misinterpreted citation by von Ihering (1931). The latter author, under a brief diagnosis of R. strigatus, cited: "Distribuicao: (typo) Amazonas, sem mais indicacao alem do nome do colleccionador Arnold, mas cujo material provem principalmente do rio da Prata" (Distribution: (type) Amazonas, without further indication besides the collector name Arnold, but that material mainly originates from rio da Prata) (von Ihering 1931: 263). In fact, von Ihering referred to the rio de La Plata basin, from where R. punctatus Boulenger was often misidentified as R. strigatus in the past (e.g. Ringuelet et al. 1967), not to the small rio da Prata in Para, unknown for most ichthyologists and still almost inaccessible at present. The geographic position of the "rio da Prata" mentioned by von Ihering may be clarified when examining other parts of his paper. For example, among other localities, he cited the occurrence of Phalloceros caudimaculatus (Hensel) for the "rio da Prata, Paraguay" (von Ihering 1931: 246).

Huber (1992) considered both R. strigatus and R. dibaphus as synonyms of R. geayi, a species first described from Amapa, northern Brazil, but also occurring in the Guianas (e.g. Huber 1991, 1992). According to Huber (1991), the three nominal species would have near type localities, but in fact the type locality of R. geayi is about 480 km and 560 km in a straight line from the type locality of R. strigatus and R. dibaphus, respectively, and type locality of R. strigatus is about 710 km from the type locality of R. dibaphus. Comparison of material of R. strigatus with material from the type locality region of R. geayi revealed that R. strigatus is a distinct and valid species, easily distinguished from R. geayi by having a rounded caudal fin in the male (vs. subtruncate) and frontal squamation F-patterned (vs. usually E-patterned). Rivulus dibaphus is also a valid species. Examination of the type material of R. dibaphus and material collected in the type locality region revealed that it may be readily distinguished from R. strigatus and R. geayi by the unique colour pattern on the caudal peduncle in the male (Figs 31-32) and that the frontal squamation is always E-patterned.

Owiyeye corresponds to the "R. rectocaudatus species group" diagnosed by Thomerson et al. (1992) and the "R. rectocaudatus superspecies" diagnosed by Huber (1992). This clade is well supported both by morphological (the present study) and molecular data (Murphy et al. 1999, Hrbek & Larson 1999, Hrbek et al. 2004). Owiyeye and Anablepsoides share two derived conditions (frontal squamation S-patterned and a transverse stripe through chin), but it is parsimoniously considered to a member of a clade also including Laimosemion and Melanorivulus, mainly diagnosed by the absence of second pharyngobranchial teeth. Seven species of Owiyeye are found in the Brazilian Amazon, all described in recent years: R. romeri, R. kirovskyi, R. uatuman, R. uakti, R. amanapira, and R. tecminae. Rivulus kirovskyi and R. duckensis are identical and were collected at the same locality. Both original descriptions were published in 2004, but the name R. kirovskyi has chronological priority over R. duckensis, since the former was published on 30 April, the latter on 20 August.

Melanorivulus corresponds to the "R. punctatus superspecies" diagnosed by Huber (1992) or the "Rivulus punctatus species-complex" diagnosed by Costa (1995a). This clade is strongly supported by morphology, and is also corroborated by molecular studies (e.g. Murphy et al. 1999, Hrbek & Larson 1999). It includes four species endemic to the Brazilian Amazonas basin: R. modestus, R. zygonectes, R. violaceus, and R. litteratus.

As already noted in previous studies (e.g. Costa 1998a, Murphy et al. 1999, Hrbek & Larson 1999), species of Rivulus endemic to the Amazonas basin do not form a monophyletic assemblage. Species from southern Amazonas tributaries, running on the Brazilian Shield (i.e., belonging to Melanorivulus) are more closely related to species endemic to basins to South and East (i.e., Parana, Paraguay, Sao Francisco and Parnaiba river basins). On the other hand, species occurring in northern and western Amazonas tributaries arising from the Andes or the Guyana Shield (i.e., belonging to Cynodonichthys, Laimosemion and Owiyeye) are more closely related to species endemic to the Orinoco and Guianas basin. This is probably a historic consequence of the past isolation of rivers draining the Brazilian Shield before the formation of the present Amazonas basin, as described in geological studies (e.g. Beurlen 1970, Lundberg et al. 1998).

Field observation on the habitat of Amazonian species of Rivulus revealed that different lineages occupy distinct kinds of habitat. This is most clear for the clade Benirivulus + Laimosemion + Owiyeye + Melanorivulus, in which members of each genus are found in a particular kind of aquatic environment, thus suggesting divergent specializations during the evolution of the group.

In Benirivulus, individuals were collected near the margin of stagnant streams and lakes (about 50-150 cm deep), with dense aquatic vegetation, at the forest border (Fig. 25). Species of Laimosemion, Owiyeye and Melanorivulus were collected in shallower places (about 5-40 cm). Possibly, the ecological preference noted for Benirivulus is the primitive condition for the clade Benirivulus + Laimosemion + Owiyeye + Melanorivulus, since species of Anablepsoides, the putative sister group to the above mentioned clade, live in similar habitats.

Amazonian species of Laimosemion were uniquely found in clear water streams, with moderate current and sandy bottom (Figs 29 and 33). No other species from the Amazonas basin inhabits a similar environment, but R. xiphidius and R. geayi, two species of Laimosemion from Guyana, seem to live in the same environmental conditions (Huber 1979). However, R. agilae, another species of Laimosemion from Guyana, has been reported as living in sunny places (Huber 1979).

Only species of Owiyeye were found in extremely shallow temporary pools (about 5-10 cm deep) with tea-coloured water (Figs 36 and 41). Since some species of Owiyeye were uniquely found in temporary pools, they possibly are semiannual fishes. An exception is R. uakti, which inhabit marginal zones of creeks at the forest border (Fig. 39).

Species of Melanorivulus are found in sunny creeks (Fig. 45) in savanna-like environments. However, this is not a unique condition among Amazonian Rivulus, since R. urophthalmus, R. taeniatus, and R. micropus are also found in sunny creeks, often near the border of forests (Figs 11, 17 and 20). These conditions are interpreted as independently derived, because Melanoorus and Cynodonichthys are not closely related taxa, and basal rivulids (i.e. basal species of Kryptolebias and Prorivulus) inhabit dark forested habitats (Costa 2004a, 2004c, Vermeulen & Hrbek 2005).

Acknowledgements

Thanks are due to E. Araujo, F. Autran, S. Barrera, D. Belote, C. P. Bove, G. C. Brasil, M. Britto, C. Campinha, B. B. Costa, R. D. Cunha, R. D'Arrigo, M. I. Landim, S. M. Q. Lima, C. Moreira, R. Paiva, A. Pinto, D. Ramos, A. Sarraf, K. Tanizaki, E. Vicente, and L. Villa-Verde, for help in collecting trips; to H. Berkenkamp, G. Brasil, H. Britski, J. Carvalho, D. Catania, J. L. Figueiredo, K. Hartel, J. Huber, M. Kottelat, S. Kullander, M. Lacerda, P. Lucinda, N. Menezes, D. Moraes Jr., G. Nunan, O. Oyakawa, L. Parenti, C. Pereira, L. Py-Daniel, U. Romer, J. Sarmiento, D. Taphorn, D. Teixeira, and J. Zuanon, for the loan, exchange, or donation of specimens, or for support during visits to their institutions. Collecting trips were supported by Fundacao o Boticario de Protecao a Natureza. This study was funded by CNPq-MCT and FAPERJ. Material was collected with permits 02001.001660/98 and 02.022005956/02 from IBAMA (Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renovaveis-Ministerio do Meio Ambiente, dos Recursos Hidricos e da Amazonia Legal).

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Appendix 1

The list below includes material examined, except belonging to species of the Brazilian Amazonas basin, which are listed in the "Taxonomic accounts" above. Data on material is organized in the following sequence: catalogue number, number of specimens, locality. Abbreviations are: c & s, specimens cleared and stained for bone and cartilage, H, holotype, and P, paratype(s). Institutional acronyms are listed in material and methods.

Aplocheilidae: Aplocheilus panchax: UFRJ 3140, 2; UFRJ 3141, 2 (c & s); Indonesia: Sulawesi: Desa Radda. Nothobranchiidae: Scriptaphyosemion guignardi: UFRJ 3883, 8; UFRJ 4110, 4 (c & s); Guinea: Dalaba. Rivulidae: Aphyolebias boticarioi: UFRJ 5986, H; UFRJ 5987, 11 P; UFRJ 5988, 5 P; Brazil: Estado do Acre: Porto Acre. Gnatholebias hoignei: MCNG 1116, 18; Venezuela: Portuguesa: La Trinidad. UFRJ 6116, 6; UFRJ 6117, 5 (c & s); Venezuela: Portuguesa: Papelon. Kryptolebias brasiliensis: UFRJ 3458, 32; UFRJ 3682, 1 (c & s); UFRJ 4603, 2 ex. (c & s); UFRJ 5332, 6 ex. (c & s); Brazil: Rio de Janeiro: Mage. Micromoema xiphophora: MCNG 26440, 20; Venezuela: Amazonas: Isla Raton. UFRJ 3165, 1 (c & s); aquarium material. Moema apurinan: UFRJ 5980, H; UFRJ 5981, 9 P; UFRJ 5982, 7 P (c & s); Brazil: Estado do Acre: Porto Acre. Neofundulus paraguayensis: UFRJ 3647, 10; UFRJ 3648, 4 (c & s); Brazil: Mato Grosso do Sul, about 70 km NW from de Aquidauana. Pituna compacta: UFRJ 3563, 33; UFRJ 3564, 4 (c & s); Brazil: Tocantins: Barreira do Piqui. Prorivulus auriferus: UFRJ 5932, H; UFRJ 5933, 4P; UFRJ 5934, 3P (c & s); Brazil: Bahia: Valenca. Rachovia maculipinnis: MCNG 35565, 2; Venezuela: Portuguesa: Sabaneta. UFRJ 6118, 7; UFRJ 6119, 4 (c & s); Venezuela: Portuguesa: Papelon. R. stellifer: MCNG 25828, 9; Venezuela: Portuguesa: La Capilla. UFRJ 245, 5 (c & s); Venezuela: Cojedes: 1 km N of Cano Benito. Renova oscari: MCNG 35926, 2; Venezuela: Amazonas: Isla Raton. UFRJ 4606, 3 (c & s): aquarium material. Rivulus amphoreus: UFRJ 3889, 2, UFRJ 4606, 3 (c & s); Surinam: Tafelberg. R. apiamici: MZUSP 39976, H; MZUSP 39977, 3P (c & s); UFRJ 5971, 4; UFRJ 5972, 3 (c & s); Brazil: Mato Grosso do Sul; Bataguacu. R. bahianus: UFRJ 3167, 44; UFRJ 4602, 2 (c & s); UFRJ 277, 1 (c & s); Brazil: Bahia: Busca-Vida. R. brunneus: MZUSP uncatalogued, 10 (2 c & s); Panama: Isla de Barro Colorado. R. chucunaque: USNM 293487, 68 (1c & s); Panama. R. cladophorus: UFRJ 643, 4P (2c & s); Guyana: Fourgassier. R. cryptocallus: UFRJ 359, 3; UFRJ 2126, 1 (c & s); Martinique: Ravine Vilaine. R. cyanopterus: UFRJ 5911, H; UFRJ 5913, 36P; UFRJ 5914, 5P (c & s); Brazil: Mato Grosso: Jaciara. R. cylindraceus: MHNC uncat., 6; Cuba: Zapata. USNM uncat., 1 (c & s); Cuba: La Habana. R. dapazi: UFRJ 5915, H; UFRJ 5916, 3P; UFRJ 5917, 2P (c & s); Brazil: Mato Grosso do Sul: Sonora. R. decoratufs: MZUSP 39982, H; MZUSP 39983, 4P; UFRJ 2135, 3 (c & s); Brazil: Bahia: Ibiraba. R. derhami: UFRJ 392, 2 (c & s); Peru: Tingo Maria. R. depressus: UFPB 2213, H; UFPB 1749, 17 (2 c & s); UFRJ 2118, 1 (c & s); Brazil: Bahia: Porto Seguro. R. elongatus: MUSM 336, 6; MZUSP 26211, 3; Peru: Ucayali: Pucallpa. R. egens: UFRJ 5973, H; UFRJ 5974, 17P; UFRJ 5975, 3P (c & s); Brazil: Mato Grosso do Sul: Camapua. R. erberi: UFRJ 358, 3; Ecuador: Napo: Coca. R. fuscolineatus: USNM 219778, 10P; Costa Rica: Guanacaste: Tilaran. R. geayi: MZUSP uncatalogued Brazil: Amapa: Serra do Navio. R. haraldsiolii: UFRJ 125, 6; UFRJ 6295, 2 (c & s); Brazil: Santa Catarina: Joinville. R. hartii: MCZ 26092, 3; Trinidad: Port of Spain. MZUSP 37204, 3; MZUSP 38472, 2 (c & s); Venezuela: Nueva Esparta: Isla de Margarita. R. hildebrandi: USNM 92958, 1P; Panama: Chiriqui: Boquete. R. holmiae: USNM 66302, 1P; Guiana: Holmia. R. igneus: UFRJ 3888, 6; UFRJ 4595, 2 (c & s); Suriname: Creek Colibri. R. immaculatus: USNM 308411, 2P; Venezuela: Bolivar: Elena de Uairen. R. janeiroensis: UFRJ 5333, 8; UFRJ 130, 2 P (c & s); UFRJ 5416, 7 (c & s); Brazil: Rio de Janeiro: Mage. R. luelingi: UFRJ 161, 8, UFRJ 127, 5 (c & s); Brazil: Santa Catarina: Araquari. R. lungi: ZSM 27825, 15; Brazil: Amapa: rio Flechal. R. nicoi: MCNG 23891, H; MCNG 23892, 1P; MCNG 23893, 1P; Venezuela: Amazonas: rio Ventuari floodplains. R. nudiventris: MZUSP 40283, H; MZUSP 40284, 3P; MNRJ 11740, 2P (c & s); Brazil: Espirito Santo: Itapemirim. R. paracatuensis: MCP 29639, H; MCP 29640, 1P; UFRJ 2290, 3P (c & s); Brazil: Minas Gerais: Brasilandia de Minas. R. parnaibensis: MCP 29639, H; UFRJ 4962, 25P; UFRJ 5449, 4P (c & s); Brazil: Piaui: Sao Dimas. R. pictus: MNRJ 11550, H; MNRJ 11551, 2P; UFRJ 5959, 2 ex. (c & s); Brazil: Distrito Federal: Planaltina. R. pinima: MZUSP 39978, H; MZUSP 39984, 2P; UFRJ 5960, 20; UFRJ 5961, 4 (c & s); Brazil: Goias: Rio Verde. R. punctatus: UFRJ 975, 9; UFRJ 2110, 4 (c & s); Brazil: Mato Grosso do Sul: Aquidauana. R. rossoi: UFRJ 5976, H; UFRJ 5977, 7P; UFRJ, 5978, 4P (c & s); Brazil: Mato Grosso do Sul: Campo Grande. R. rubrolineatus: MZUSP 26371, 3; MUSM 1465, 6; Peru: Loreto: Jenaro Herrera. R. rutilicaudus: UFRJ 5965, H; UFRJ 5966, 12P; UFRJ 5967, 3P (c & s); Brazil: Goias: Serranopolis. R. santensis: UFRJ 5441, 11; UFRJ 6294, 5 (c & s); Brazil: Sao Paulo: Boraceia. R. simplicis: UFRJ 5940, H; UFRJ 5976, 3P; UFRJ 5942, 5P (c & s); Brazil: Rio de Janeiro: Parati. R. scalaris: UFRJ 5968, H; UFRJ 5969, 19P; UFRJ 5970, 4P (c & s); Brazil: Mato Grosso do Sul: Costa Rica. R. stagnatus: UFRJ 3890, 3; UFRJ 4605, 4 (c & s); Suriname: Wageningen. R. tenuis: UFRJ 4600, 4; UFRJ 4601, 2 (c & s); Guatemala: Alta Verapaz: Sebol. R. vittatus: MZUSP 39981, H; MZUSP 39981, 6P; UFRJ 2206, 15; UFRJ 5962, 4 (c & s); Brazil: Goias: Cachoeira Alta. R. xiphidius: UFRJ 4608, 3 (c & s); Guyana (specimens born in aquarium). Trigonectes rubromarginatus: UFRJ 3553, 13; UFRJ 3554, 3 (c & s); Brazil: Tocantins: Barreira do Piqui.

Appendix 2

Characters (in brackets) and character states (in parentheses) used to erect the phylogenetic hypothesis among species of Rivulus and other rivulids are listed below, with the respective reference to papers where the character is first described or discussed. Distribution of character states among terminal taxa is presented in the data matrix in Appendix 3.

Superficial dermal bones and neurocranium

[1] Lachrymal (Parenti 1981; Costa 1998a, 1998b) (CI: 1.00; RI: 1.00): (0) flat, posterior rim wide; (1) slightly twisted, posterior rim reduced, bone formed mainly by canal; (2) very twisted and narrow, slender, canal vestigial.

[2] Ventral portion of lachrymal (Costa 1998a) (CI: 0.50; RI: 0.66): (0) short; (1) expanded.

[3] Dermosphenotic (Costa 2004d): (CI: 1.00; RI: 1.00): (0) present; (1) absent.

[4] Vomerine teeth (Costa 1998a) (CI: 0.40; RI: 0.80): (0) usually 1-4, sometimes 5-6; (1) 6-12; (2) teeth absent [not ordered].

[5] Anterior retrorse process of lateral ethmoid (Costa 1990) (CI: 1.00; RI: 1.00): (0) short; (1) moderate to elongate.

[6] Lateral process of sphenotic (Costa 2005b) (CI: 0.50; RI: 0.50): (0) narrow; (1) wide.

[7] Anterolateral process of parasphenoid (Costa 1998a) (CI: 0.16; RI: 0.78): (0) short, free; (1) long, attached to pterosphenoid.

[8] Posterior portion of parasphenoid (Costa 2005b) (CI: 0.50; RI: 0): (0) wide; (1) narrow.

[9] Lateral border of frontal (Costa 1998a) (CI: 1.00; RI: 1.00): (0) well-ossified, approximately straight; (1) poorly ossified, concave.

Jaws, jaw suspensorium and opercular apparatus

[10] General shape of the premaxilla and dentary (Costa 1998a) (CI: 0.25; RI: 0): (0) elongate, snout profile sharply pointed; (1) short, snout profile blunt.

[11] General shape of ascending process of premaxilla (modified from Parenti, 1981, Costa 1998b) (CI: 1.00; RI: 1.00): (0) curved, posterior portion medially directed; (1) approximately straight.

[12] Ascending process of premaxilla (Costa 2005b) (CI: 0.50; RI: 0): (0) wide; (1) narrow.

[13] Ventral process of maxilla (Parenti 1981, Costa 1998a) (CI: 1.00; RI: 1.00): (0) slightly curved, anterior margin rounded; (1) bent, anterior margin triangular.

[14] Maxilla (modified from Parenti 1981) (CI: 0.40; RI: 0.72): (0) approximately straight; (1) slightly twisted; (2) greatly twisted.

[15] Rostral cartilage (Costa 1998a) (CI: 0.25; RI: 0.40): (0) approximately rounded; state 1: longitudinal length longer than transversal length.

[16] Posterior portion of rostral cartilage (Costa 2004a) (CI: 0.20; RI: 0.69): (0) not distinctively narrowed; (1) distinctively narrowed.

[17] Coronoid process of dentary (Costa 1998a) (CI: 1.00; RI: 1.00): (0) broad; (1) narrow.

[18] Ventral process of angulo-articular (modified from Costa 1990, 1998a) (CI: 0.66, RI: 0.81): (0) large and broad; (1) large, somewhat narrowed; (2) moderate, narrow and pointed; (3) vestigial; (4) long and somewhat narrowed [not ordered].

[19] Curvature of ventral process of angulo-articular (Costa 1998a) (CI: 1.00, RI: 1.00): (0) straight; (1) curved.

[20] External medial teeth of premaxilla and dentary (Costa 1998a) (CI: 0.33; RI: 0.50): (0) approximately directed as other teeth; (1) laterally displaced, strongly contrasting to other teeth.

[21] Ventral portion of palatine (Costa 1998a) (CI: 1.00; RI: 1.00): (0) long, overlapping dorsal portion of quadrate; state 1: short, not or slightly contacting quadrate.

[22] Metapterygoid (modified from Costa 1998a) (CI: 0.66; RI: 0.90): (0) about rectangular, dorsal and ventral portions wide and approximately equal in width; (1) dorsal portion slightly constricted; (2) about triangular, dorsal portion strongly constricted.

[23] Posterior process of quadrate (Costa 1998a) (CI: 0.50; RI: 0.50): (0) short, about 50% of quadrate length; (1) long, about 70% of quadrate length.

[24] Preopercle (Costa 1990) (CI: 1.00; RI: 1.00): (0) robust, L-shaped, with a well-developed anteromedian rim; (1) thin, Cshaped, with a reduced anteromedian rim.

[25] Dorsal arm of preopercle (Costa 1990) (CI: 0.50; RI: 0.85): (0) broad; (1) narrow and pointed.

Hyoid and branchial arches

[26] Anterior process of urohyal (Costa 1998a) (CI: 1.00; RI: 1.00): (0) short; (1) elongate.

[27] Dorsal process of urohyal length (CI: 1.00; RI: 1.00): (0) present; (1) absent; (?) very short to absent.

[28] Dorsal process of urohyal length (Costa 1998a) (CI: 0.25; RI: 0.85): (0) short; (1) elongate; (?) process absent.

[29] Basihyal (Costa 1998a) (CI: 0.50; RI: 0): (0) shorter than space occupied by basibranchials; (1) longer than space occupied by basibranchials.

[30] Basihyal cartilage extent, as percentage of basihyal length (modified from Costa 1998a) (CI: 0.40; RI: 0.62): (0) 50-70 %; (1) 20-40 %; (2) 10-15 %.

[31] Interhyal (Parenti 1981) (CI: 1.00; RI: 1.00): (0) ossified; (1) cartilaginous.

[32] Interhyal (Costa 2005b) (CI: 1.00; RI: 1.00): (0) large; (1) minute.

[33] Number of branchiostegal rays (Costa 2004e) (CI: 0.33; RI: 0): (0) 6; (1) 5.

[34] Main axis of first epibranchial (Costa 1998a) (CI: 1.00; RI: 1.00): (0) approximately straight; (1) curved.

[35] Subdistal process of second epibranchial (Costa 2004a) (CI: 1.00; RI: 1.00): (0) present; (1) absent.

[36] Uncinate process of third epibranchial (modified from Costa 1998a, b) (CI: 1.00; RI: 1.00): (0) long; (1) moderate; (2) short.

[37] Interarcual cartilage (modified from Parenti 1981) (CI: 1.00; RI: 1.00): (0) not reduced; (1) reduced (CI: 1.00; RI: 1.00).

[38] Number and arrangement of second pharyngobranchial teeth (Costa 2004a) (CI: 0.50; RI: 0.88): (0) numerous teeth arranged in two rows; (1) few teeth arranged in single row; (2) teeth absent [not ordered].

[39] Proximal edge of first hypobranchial (Costa 1998a) (CI: 0.33; RI: 0.33): (0) plain, terminating in single cartilage united to second basibranchial; (1) bifid, terminating in cartilage united to second basibranchial and another smaller cartilage united to first basibranchial.

[40] Distal edge of first hypobranchial (Costa 2004a) (CI: 1.00; RI: 1.00): (0) articular face restricted to cartilaginous head of first ceratobranchial; (1) articular face anteriorly expanded.

[41] Orientation of anterior tip of fifth ceratobranchial (Costa 2005b) (CI: 0.50; RI: 0.50): (0) anterior; (1) anterolateral.

Vertebrae and caudal skeleton

[42] Pointed, anteriorly directed process on first vertebra (modified from Costa 1990) (CI: 1.00; RI: 1.00): (0) absent; (1) present.

[43] Epipleural ribs (Parenti 1981, Costa 1998a) (CI: 0.50; RI: 0.66): (0) rod-like; (1) bifid.

[44] Neural prezygapophyses (Costa 1990) (CI: 0.33; RI: 0.84): (0) short; (1) long.

[45] Hypurals (modified from Costa 1998a) (CI: 0.42; RI: 0.33): (0) two dorsal plates and one ventral plate separated by gap; (1) two plates separated by wide gap; (2) two plates in close proximity, sometimes ankylosed; (3) single plate.

[46] Proximal end of parahypural (Costa 1998b) (CI: 1.00; RI: 1.00): (0) robust with paired dorsal processes overlapping preural centrum; (1) shortened and laminar, without dorsal paired process, not contacting preural centrum.

[47] Hemal spine of preural centrum two (Costa 1998b) (CI: 0.50; RI: 0): (0) distinctively wider than hemal spines anterior to it; (1) slightly wider or equal in width to hemal spines anterior to it.

[48] Number of vertebrae (modified from Costa 1990) (CI: 0.18; RI: 0.52): (0) 29-32; (1): 33-35; (2) 36-38.

[49] Number of caudal-fin rays (modified from Costa 1990) (CI: 0.18; RI: 0.59): (0) 26-31; (1) 32-36; (2) 24-25 [not ordered].

Dorsal- and anal-fin skeleton

[50] First dorsal-fin ray (modified from Parenti, 1981) (CI: 1.00; RI: 1.00): (0) single long first ray connected to two proximal radials; (1) long fin ray connected to two proximal radials, preceded by one or two short fin rays.

[51] Anterior proximal radials of dorsal and anal fins (Costa 2005b) (CI: 1.00; RI: 1.00): (0) slender; (1): wide.

[52] Number of anal-fin rays (modified from Costa 1998a) (CI: 0.28; RI: 0.44): (0) 9-15; (1) 16-20; (2) 25-26.

[53] Orientation of anterior proximal radials of anal fin (modified from Costa 1998a) (CI: 1.00; RI: 1.00): (0) anteriorly or dorsally directed; (1) posteriorly directed.

Shoulder and pelvic girdle

[54] Pectoral-fin insertion (Costa 1998b) (CI: 1.00; RI: 1.00): (0) lateral; (1) ventrolateral.

[55] Supracleithrum and posttemporal (modified from Parenti 1981, Costa 1998b) (CI: 0.66; RI: 0.50): (0): separated; (1) co-ossified, limits almost inconspicuous; (2) fused to form a single structure.

[56] Keel along supracleithrum-posttemporal (Costa 2005b) (CI: 1.00; RI: 1.00): (0) absent; (1) present.

[57] Ventral process of posttemporal (Parenti 1981, Costa 1998a, b) (CI: 0.20; RI: 0.81): (0) present; (1) absent.

[58] Posterior flange of cleithrum (Costa 1998a) (CI: 1.00; RI: 1.00): (0) present; (1) absent.

[59] First postcleithrum (Parenti 1981) (CI: 1.00; RI: 1.00): (0) present; (1) absent.

[60] Fourth pectoral radial (Costa 1998a) (CI: 0.33; RI: 0.75): (0) not expanded; (1) ventrally expanded.

[61] Ischial process of pelvic girdle (Costa 2005b) (CI: 1.00; RI: 1.00): (0) prominent; (1) vestigial.

[62] Number of pectoral-fin rays (modified from Costa 1998a): (0) 13-15; (1) 16-17.

[63] Number of pelvic-fin rays (Costa 1990) (CI: 1.00; RI: 1.00): (0) six; (1) seven; (2) eight.

External morphology of body and head

[64] Mouth (Costa 1998b) (CI: 1.00; RI: 1.00): (0) terminal; (1) superior.

[65] Orbital rim (modified from Parenti 1981) (CI: 1.00; RI: 1.00): (0) free dorsally, attached ventrally; (1) completely attached.

[66] Branchiostegal and opercular membranes (Parenti 1981) (CI: 1.00; RI: 1.00): (0) separated by long fold; (1) continuous.

[67] Skin fold on corner of preopercular region (Costa 2005b) (CI: 1.00; RI: 1.00): (0) present; (1) absent.

External morphology of fins

[68] Pectoral fin (Costa 1990) (CI: 0.50; RI: 0.75): (0) rounded; (1) pointed.

[69] Pectoral-fin length (modified from Parenti 1981) (CI: 0.33; RI: 0.75): (0) 17.0-23.8 % SL; (1) 24.1-31.1 % SL.

[70] Extent of pelvic fin in males (Costa 1998a) (CI: 0.25; RI: 0.25): (0) short, tip not surpassing anterior portion of anal fin; (1) long, its tip reaching the central or the posterior portion of the anal fin.

[71] Pelvic-fin (Costa 2005b) (CI: 1.00; RI: 1.00): (0) bases separated or in contact; (1) bases united; (2) pelvic fins united along proximal portion of medial margin.

[72] Dorsal fin (modified from Costa 1998a) (CI: 0.33; RI: 0.84): (0) short, tip rounded; (1) somewhat elongated, tip pointed; (2) long, tip sharply pointed.

[73] Anal fin (modified from Costa 1998a) (CI: 0.22; RI: 0.75): (0) short, tip rounded; (1) somewhat elongated, tip pointed; (2) long, tip sharply pointed.

[74] Filaments on tip of dorsal and anal fins in males (Costa 1998a) (CI: 0.50; RI: 0.66): (0) absent; (1) present.

[75] Filaments on posterior border of caudal fin in males (Costa 1998a) (CI: 0.33; RI: 0.60): (0) absent; (1) present.

[76] Caudal-fin length in males (Costa 1990) (CI: 0.40; RI: 0.70): (0) 29.0-41.5; (1) 42.0-49.0; (2) 52.5-81.0.

[77] Caudal-fin shape in males (CI: 0.33; RI: 0.40): (0) rounded; (1) subtruncate; (2) truncate; (3) acuminate [not ordered].

[78] Dorsal and ventral extensions on caudal fin in males (Costa 1998a) (CI: 0.50; RI: 0): (0) absent; (1) present.

Squamation

[79] General arrangement of frontal scales (Hoedeman 1958) (CI: 0.50; RI: 0.85): (0) transverse; (1) circular; (2) irregular [not ordered].

[80] Predominant frontal squamation-pattern (Hoedeman 1958) (CI: 0.28; RI: 0.52): (0) G; (1) E; (2) D; (3) F; (4) S [not ordered].

[81] Arrangement of E-scales (Costa 1990) (CI: 1.00; RI: 1.00): (0) overlapped; (1) not overlapped.

[82] Caudal-fin squamation in older males (Costa 1990, 1998a) (CI: 0.25; RI: 0.57): (0) approximately on anterior 10-30 % of fin; (1) approximately on 40 % of fin; (2) approximately on 50-80 % of fin.

[83] Anal-fin base squamation in males (Costa 2005b) (CI: 1.00; RI: 1.00): (0) no scales on anal-fin base; (1) 1-7 rows of scales on anal-fin base.

Laterosensory system

[84] Cephalic canals (modified from Parenti 1981) (CI: 0.75; RI: 0.92): (0) anterior and posterior infraorbital, preopercular and posterior mandibular closed, supraorbital, rostral, anterior mandibular open with skin trenches around neuromasts; (1) anterior and posterior infraorbital, and preopercular closed, supraorbital, rostral, anterior and posterior mandibular open with skin trenches around neuromasts; (2) anterior and posterior infraorbital, dorsal preopercular, supraorbital, rostral, anterior and posterior mandibular open with skin trenches around neuromasts; (3) no vestige of canals, all neuromasts completely exposed.

[85] Number of anterior supraorbital neuromasts (Costa 1990) (CI: 0.50; RI: 0.33): (0) 3; (1) 4; (2) 6-7.

[86] Arrangement of anterior supraorbital neuromasts (Costa 2004d) (CI: 1.00; RI: 1.00): (0) continuous row; (1) posteriormost neuromast separated by space covered by scale.

[87] Arrangement of anterior and posterior rostral neuromast (CI: 1.00; RI: 1.00): (0) longitudinal; (1) transverse.

Contact organs

[88] Contact on flank scales in males (Costa 2005b) (CI: 0.14; RI: 0.66): (0) absent; (1) present.

Male colour patterns

[89] Red marks on male flank (CI: 0.16; RI: 0.44): (0) absent; (1) present.

[90] Kind of red marks on male flank (CI: 0.44; RI: 0.69): (0) vertical rows of dots, sometimes forming stripes; (1) vertical rows of dots on anterior portion, chevron-like bars on posterior; (2) dots on chevron-like series on entire flank, sometimes forming oblique bars; (3) overlapping longitudinal and oblique rows; (4) red marks irregularly arranged, not forming any distinguishable pattern; (?) red marks absent [not ordered].

[91] Dark pigmentation pattern on humeral region (modified from Costa 1998a) (CI: 0.33; RI: 0.50): (0) not distinctively coloured; (1) forming distinct blotch.

[92] Dark pigmentation pattern on upper portion of caudalfin base (Costa 2005b) (CI: 0.50; RI: 0.40): (0) not distinctively coloured; (1) forming distinct blotch.

[93] Dark pigmentation on anterior half of flank when fish is exposed to sunlight (modified from Costa 1998a) (CI: 0.20; RI: 0.80): (0) not distinctively marked; (1) forming grey vertical bars; (2) forming dark grey broad stripe; (3) forming dark grey oblique bars [not ordered].

[94] Dark pigmentation between dorsum and flank (modified from Costa, 1998a) (CI: 1.00; RI: 1.00): (0) not distinctively marked; (1) forming longitudinal dark zone.

[95] Dark pigmentation pattern on iris (Parenti 1981) (CI: 1.00; RI: 1.00): (0) no distinctive mark; (1) bar crossing eye.

[96] Pigmentation pattern on suborbital region (Costa 1998a) (CI: 0.66; RI: 0.75): (0) no distinctive mark; (1) grey to black suborbital bar; (2) red suborbital spot [not ordered].

[97] Pigmentation pattern on post-orbital and preopercular region (Costa 1998a) (CI: 0.40; RI: 0.66): (0) no distinctive pattern; (1) two oblique bars; (2) post-orbital vertical bar; (3) two oblique stripes [not ordered].

[98] Dark pigmentation pattern on lower jaw (Costa 2004d) (CI: 0.33; RI: 0.84): (0) not distinctively concentrated; (1) jaw dark grey to black; (2) transverse stripe through chin [not ordered].

[99] Dark blue to dark purplish blue iridescence on opercular and infraorbital region (Costa 1998a) (CI: 0.25; RI: 0.57): (0) absent; (1) present.

[100] Dark pigmentation on distal portion of male anal fin (Costa 1998a) (CI: 0.20; RI: 0.50): (0) not distinctive concentrated; (1) concentrated to form stripe.

[101] Yellow to orange pigmentation pattern on ventral portion of caudal fin (modified from Costa 1998a) (CI: 0.10; RI: 0.55). (0) not distinctive concentrated; (1) concentrated to form stripe; (?) variable.

[102] Yellow to orange pigmentation pattern on dorsal portion of caudal fin (modified from Costa 1998a) (CI: 0.11; RI: 0.50). (0) not distinctive concentrated; (1) concentrated to form stripe; (?) variable.

[103] Dark pigmentation of ventral margin of male caudal fin (modified from Costa 1998a) (CI: 0.33; RI: 0.75): (0) not distinctive concentrated; (1) concentrated to form stripe.

[104] Red pigmentation pattern on subventral portion of caudal fin (CI: 0.33; RI: 0.66): (0) not distinctive concentrated; (1) concentrated to form stripe.

[105] Red pigmentation on caudal fin (modified from Costa 1998a) (CI: 0.33; RI: 0.66): (0) not distinctive arranged; (1) forming bars.

[106] Dark pigmentation on dorsal portion of caudal fin (Costa 1998a) (CI: 0.50; RI: 0.75): (0) not distinctive concentrated; (1) concentrated to form dark brown stripe; (?) variable.

[107] Melanophore pattern on pectoral fin (Costa 1998a) (CI: 0.33; RI: 0): (0) no distinctive marks; (1) spots; (2) bars [unordered].

[108] Colour of pectoral fin (CI: 0.33; RI: 0.50): (0) hyaline; (1) yellow.

Female colour patterns

[109] Dark pigmentation pattern on flank and fins (Costa 1998a) (CI: 0.50; RI: 0): (0) forming bars, stripes or spots, according to the pattern occurring in males; (1) flank almost plain, pigmentation reduced to minute dots, not presenting the general pattern as in males.

[110] Red marks on flank (CI: 0.25; RI: 0.84): (0) absent; (1) present.

[111] Melanophore pattern on unpaired fin margins (Costa 1995a) (CI: 1.00; RI: 1.00): (0) not distinctively concentrated; (1) forming black zones of marginal regions.

[112] Dark pigmentation pattern on upper portion of caudalfin base (Costa 1990) (CI: 0.14; RI: 0.71): (0) no distinctive mark; (1) one black spot.

[113] Kind of caudal blotch (CI: 0.66; RI: 0.85): (0) black blotch close to fin margin, surrounded by light area to form an ocellate spot; (1) black blotch close to or contacting fin margin, anteriorly bordered by triangular light spot; (2) black blotch apart from fin margin, with light area surrounding anterior, dorsal and posterior margin; (?) caudal blotch absent.

Appendix 3

Matrix of 113 characters for 49 aplocheiloid species. Characters and states are according to Appendix 2. Autapomorphies were excluded from the analysis; 0 = plesiomorphic state; 1-4 = apomorphic states; ? = not pertinent or unknown state.
                    1-10        11-20       21-30       31-40

A. panchax          0000000000  0000000000  0000000000  0000000000
S. guignardi        1000000001  0100000000  0000000000  0000000200
K. brasiliensis     2000100011  0111101000  100100?002  0000010110
P. auriferus        2000101011  1112101000  1001000001  1110110110
A. boticarioi       2100101011  1111101100  1201000101  1100120111
G. hoignei          2000100110  1011001101  1101000101  11001212?1
M. xiphophora       2000100011  1112101101  1111000111  1100120111
M. apurinan         200?101110  1111101100  1201000101  1100120111
N. paraguayensis    2000111011  1111101100  1001000101  1100120111
P. compacta         2100110011  1111101300  1101100101  1100120111
P. longipinnis      2000101011  1112101201  1211000111  1100121111
R. maculipinnis     2100101011  1111101100  1101010101  1100120111
R. stellifer        2100101011  1111101100  1101010101  1100120111
R. oscari           2001101011  1112101100  1111000101  1100120111
R. amanapira        2010100011  1112101100  1001000001  1100120201
R. amphoreus        2000101011  1112111400  1001000102  1100120111
R. apiamici         2002100011  1112101300  1001100001  1101120211
R. atratus          2000101011  1112011101  1001000001  1100120111
R. bahianus         2000101011  1112111100  1001000002  1100120111
R. beniensis        2000100011  1112111100  1001000101  1100120111
R. brunneus         2000101011  1112111100  1001000101  1100120111
R. cladophorus      2002100011  1112101100  1001000001  1100120211
R. cryptocallus     2000101011  1112111400  1001000102  1100120111
R. cylindraceus     2000100011  1112001100  1001000001  1100120111
R. depressus        2000101011  1112111110  1001000001  1100120111
R. dibaphus         2002100011  1112101100  1001001?01  1100120211
R. hartii           2000101011  1112101400  1001000102  1100120111
R. igneus           2001101011  1112101400  1001000102  1100120111
R. janeiroensis     2000101011  1112111110  1001000001  1100120111
R. kirovskyi        2012100011  1112101100  1001000001  1100120211
R. litteratus       2002100011  1112101300  1001100001  1100120211
R. luelingi         2000101011  1112111110  1001000101  1100120111
R. micropus         2000101011  1112111400  1001000101  1100120111
R. modestus         2002100011  1112101100  1001100001  1100120211
R. ornatus          2000101011  1112011101  1001000001  1100120111
R. pictus           2002100011  1112101300  1001100001  1101120201
R. punctatus        2002100011  1112101100  1001100001  1100120211
R. romeri           2012100011  1112101100  1001000001  1110120211
R. santensis        2000101011  1112101110  1001000?01  1100120111
R. strigatus        2002100011  1112101100  1001001?01  1100120211
R. taeniatus        2000101011  1112111100  1001000102  1100120111
R. tecminae         2012100011  1112101100  1001000001  1100120211
R. tenuis           2000101011  1112111100  1001000101  1100120111
R. uakti            201?100011  1112101100  1001000001  1100120211
R. uatuman          2012100011  1112101100  1001000001  1110120211
R. urophthalmus     2000101011  1112111100  1001000102  1100120111
R. violaceus        2002100011  1112101100  1001100001  1100120211
R. zygonectes       2002100011  1112101100  1001100001  1100120211
T. rubromarginatus  2001111010  1111101400  1001000101  1100120111

                    41-50       51-60       61-70       71-80

A. panchax          0000000000  0100201000  0000000000  0000000000
S. guignardi        0010111011  0101200000  0101101000  0000001000
K. brasiliensis     0001110001  0001000010  0001111000  0000000011
P. auriferus        0100111011  0001001010  00011110?0  0000000011
A. boticarioi       1100211101  0001110111  0001111110  0221111111
G. hoignei          0100311201  1211110111  1011111111  2221121013
M. xiphophora       0100111001  0001111111  0001111110  0220013111
M. apurinan         1100111101  0101110111  0001111110  0221120011
N. paraguayensis    0100111101  0001110110  0001111010  0110000011
P. compacta         0100211001  0001110111  0001111010  0110000013
P. longipinnis      0100111001  1111110111  1011111011  1221121011
R. maculipinnis     0100211001  0001110111  0001111010  0110111013
R. stellifer        0101211101  0101110110  0001111000  0110001011
R. oscari           1100111011  0001110111  0001111110  0220110013
R. amanapira        0101111201  0001111110  0001111000  0110002004
R. amphoreus        0101111111  0101110110  0101111000  0000000011
R. apiamici         0101111011  0001111110  0001111000  0110000011
R. atratus          0101111021  0001111110  0001111000  0000013014
R. bahianus         0101111001  0001110110  0001111000  0000000011
R. beniensis        0101111021  0001111110  0001111000  0000000011
R. brunneus         0101111001  0001110110  0001111000  0000000012
R. cladophorus      0111111001  0001111110  0001111000  0000001013
R. cryptocallus     0101111111  0001110110  0001111000  0000000011
R. cylindraceus     0100311001  0001110110  0001111000  0000000011
R. depressus        0101111101  0001111110  0001111000  0000000011
R. dibaphus         0111111001  0001111110  0001111000  0110001011
R. hartii           0101111111  0101110110  0101111000  0000000012
R. igneus           0101111211  0101110110  0101111000  0000000012
R. janeiroensis     0101?11101  0001111110  0001111000  0000000011
R. kirovskyi        0101111021  0001111110  0001111000  0000000004
R. litteratus       0101111011  0001111110  0001111000  0110000013
R. luelingi         0101111001  0001111110  0001111000  0000000011
R. micropus         0101111101  0001110110  0001111000  0000000011
R. modestus         0101111011  0001111110  0001111000  0110000013
R. ornatus          0101111021  0001111110  0001111000  0000013014
R. pictus           0101111011  0001111110  0001111000  0110000011
R. punctatus        0101111011  0001111110  0001111000  0110000013
R. romeri           0101111021  0001111110  0001111000  0020000004
R. santensis        0101?11111  0001111110  0001111000  0000000011
R. strigatus        0111111001  0001111110  0001111000  0110000013
R. taeniatus        0101111101  0001110110  0001111000  0000000011
R. tecminae         0101111021  0001111110  0001111001  0000002004
R. tenuis           0101111001  0001110110  0001111000  0000000011
R. uakti            0101111021  0001111110  0001111001  0010000004
R. uatuman          0101111021  0001111110  0001111000  0000000004
R. urophthalmus     0101111101  0001110110  0001111000  0000000011
R. violaceus        0101111011  0001111110  0001111000  0110000013
R. zygonectes       0101111011  0001111110  0001111000  0110000013
T. rubromarginatus  0100111211  0101110111  0001111001  0220000012

                    81-90       91-100      101-110     111-113

A. panchax          000000000?  0000000100  0000000000  00?
S. guignardi        0001000011  0000001000  1101000000  00?
K. brasiliensis     000200000?  1000010101  0010000000  00?
P. auriferus        000200000?  0000000100  0000000100  00?
A. boticarioi       1002000113  0000100000  1001001010  00?
G. hoignei          101200000?  0000100000  0000010000  00?
M. xiphophora       1002000010  0000121000  1101000001  00?
M. apurinan         1002000110  0000101000  1001000000  00?
N. paraguayensis    1102100010  1000100000  1000001000  00?
P. compacta         100320010?  0000110000  0000001000  00?
P. longipinnis      101200000?  ?000100001  0000002000  00?
R. maculipinnis     120200000?  0000112000  ?100000010  00?
R. stellifer        120200000?  0000110001  0000000000  011
R. oscari           1002000010  0000120000  1001000001  011
R. amanapira        1003001110  0011000200  1100000000  011
R. amphoreus        1102001110  0000000000  0000000001  011
R. apiamici         1003001012  0000001100  0000100001  112
R. atratus          100200100?  0310000200  0000001000  00?
R. bahianus         1102001010  0010000001  1110000000  011
R. beniensis        1002001110  0010000101  0000000000  011
R. brunneus         1102001010  0000000110  1101000101  011
R. cladophorus      1002001111  1010000100  0010000001  00?
R. cryptocallus     1102001110  0110000000  1100000001  011
R. cylindraceus     1202100014  0000000100  0000000000  010
R. depressus        1002001014  0010000101  1110010000  011
R. dibaphus         1002001111  1010000100  0010100001  00?
R. hartii           1102001110  0110000010  1100000001  011
R. igneus           1102001110  0100000010  0000000001  00?
R. janeiroensis     1002001014  0010000101  1110010000  011
R. kirovskyi        1003011110  0010000200  0000000000  00?
R. litteratus       1003001014  0000001100  0000100001  112
R. luelingi         1002001114  0010000101  1110010000  012
R. micropus         1102001110  0010000010  0000000001  011
R. modestus         100300100?  0000001100  0000000000  112
R. ornatus          1002001013  0310000210  0000100000  00?
R. pictus           1003001012  0000001100  0000100001  112
R. punctatus        1003001012  0200001100  0000000001  112
R. romeri           1003011010  0010000200  0000000000  00?
R. santensis        1002001014  0010000101  1110010000  011
R. strigatus        1002001111  1010000100  1010100001  00?
R. taeniatus        1002001110  0010000010  0100000101  011
R. tecminae         1003001110  0011000200  1100000000  011
R. tenuis           1102001010  00?0000110  1101000101  011
R. uakti            1003001114  0011000200  0000000000  011
R. uatuman          1003011110  0010000200  0000000000  00?
R. urophthalmus     1002001010  0110000010  1100000101  011
R. violaceus        1003001012  0000001100  1100100001  112
R. zygonectes       1003001012  0200001100  0000000001  112
T. rubromarginatus  1102100010  0000100000  1000000000  00?


Laboratorio de Ictiologia Geral e Aplicada, Departamento de Zoologia, Universidade Federal do Rio de Janeiro, Caixa Postal 68049, CEP 21944-970, Rio de Janeiro, Brasil. E-mail: wcosta@acd.ufrj.br

Received: 08 April 06--Accepted: 15 August 06
Table I. Morphometric data of the R. urophthalmus, R. taeniatus, R.
micropus, and R. ornatus.

                      R. urophthalmus           R. taeniatus
                      males (10)  females (10)  males (10)  females (10)

Standard length (mm)  26.7-34.9   24.9-35.4     29.7-61.1   28.8-50.1
Percents of standard length
Body depth            19.6-21.9   19.5-21.9     18.7-20.9   18.6-21.7
Caudal peduncle       12.5-13.9   12.7-13.4     12.6-16.0   12.6-14.3
  depth
Pre-dorsal length     77.0-79.1   76.2-78.8     78.0-79.9   78.6-80.8
Pre-pelvic length     53.1-55.0   53.3-55.8     53.6-57.7   54.5-57.5
Length of dorsal-fin   7.0-9.1     7.1-8.5       6.1-8.5     6.5-8.5
  base
Length of anal-fin    16.7-19.3   16.0-18.7     16.6-18.7   16.3-19.1
  base
Caudal-fin length     30.4-36.2   33.1-37.4     29.0-33.3   29.0-32.4
Pectoral-fin length   17.4-19.7   17.1-20.9     17.0-20.0   16.7-19.6
Pelvic-fin length      8.0-10.0    7.7-8.9       7.9-10.6    7.1-9.1
Head length           23.0-25.4   23.1-26.2     22.8-24.8   23.0-24.9
Percents of head length
Head depth            63.7-71.2   64.5-73.7     64.1-73.8   64.7-74.5
Head width            75.6-82.9   77.9-85.7     78.2-91.8   78.7-88.3
Snout length          13.1-16.8   13.9-17.2     13.0-17.0   13.9-15.8
Lower jaw length      19.5-23.2   20.8-25.3     23.3-25.5   23.1-26.1
Eye diameter          30.5-34.5   29.3-34.5     28.4-36.7   28.0-34.9

                      R. micropus             R. ornatus
                      males (6)  females (4)  males (5)  females (4)

Standard length (mm)  31.9-42.8  30.8-41.8    19.4-21.1  19.3-19.7
Percents of standard length
Body depth            18.0-19.6  17.0-19.0    17.4-19.0  16.6-18.4
Caudal peduncle       12.9-14.1  12.4-13.4    12.7-14.4  12.5-13.4
  depth
Pre-dorsal length     77.7-80.6  77.9-81.1    78.5-81.7  81.0-84.6
Pre-pelvic length     50.5-54.5  52.5-53.9    53.3-57.0  53.6-57.3
Length of dorsal-fin   6.1-8.1    6.1-8.3      6.2-7.8    5.0-6.1
  base
Length of anal-fin    16.3-18.7  15.5-17.6    14.0-16.4  13.3-15.2
  base
Caudal-fin length     30.4-36.2  31.4-33.3    46.0-51.6  44.7-45.8
Pectoral-fin length   18.9-20.7  18.0-19.3    22.1-26.3  22.5-23.6
Pelvic-fin length      9.9-13.4   9.2-10.0    11.5-14.1  10.4-12.1
Head length           24.4-25.3  24.3-25.6    27.0-28.6  27.8-28.1
Percents of head length
Head depth            57.5-60.3  54.7-58.6    51.4-55.7  48.8-53.6
Head width            72.8-74.4  71.4-77.4    73.6-79.6  73.3-80.0
Snout length          14.8-15.1  13.9-14.2    11.5-14.3  12.0-13.5
Lower jaw length      22.8-24.2  24.6-27.0    20.2-22.8  19.1-20.3
Eye diameter          30.4-32.1  28.4-32.0    28.6-34.1  28.5-33.5

Table II. Morphometric data of Rivulus beniensis, R. strigatus, and
R. dibaphus.

                       R. beniensis          R. strigatus
                       males      females    males      females
                       (10)       (10)       (10)       (7)

Standard length (mm)   19.6-23.0  19.4-25.8  22.2-26.5  18.7-22.2
Percents of standard length
Body depth             19.8-22.0  19.5-21.3  18.8-21.9  19.2-20.8
Caudal peduncle depth  13.0-14.3  12.7-14.4  13.4-15.5  12.7-14.6
  depth
Pre-dorsal length      76.2-78.3  76.8-79.9  70.4-73.3  71.2-74.1
Pre-pelvic length      53.0-55.2  52.7-55.8  52.3-57.1  53.1-56.0
Length of dorsal-fin    8.2-9.9    7.0-9.2   10.0-12.1  10.7-12.1
  base
Length of anal-fin     17.0-20.2  16.5-17.9  17.7-19.5  16.5-18.5
  base
Caudal-fin length      34.5-39.3  34.0-37.4  36.0-41.6  36.7-42.6
Pectoral-fin length    18.2-21.1  18.8-21.2  18.8-21.1  19.4-22.7
Pelvic-fin length       9.9-11.9   8.7-10.6   9.5-11.3   8.5-10.8
Head length            25.1-27.6  24.7-26.8  25.4-27.4  25.9-27.3
Percents of head length
Head depth             63.0-67.9  60.2-66.3  63.4-68.8  63.8-68.0
Head width             71.7-79.6  72.7-77.8  73.4-79.7  73.8-80.2
Snout length           14.2-16.4  12.7-16.4  11.7-14.4  12.2-14.0
Lower jaw length       15.8-20.8  16.7-20.3  19.1-23.0  19.0-22.0
Eye diameter           33.3-36.2  31.5-37.1  33.1-35.4  32.2-37.0

                       R. dibaphus
                       males (9)  females (6)

Standard length (mm)   19.2-26.5  17.8-23.4
Percents of standard length
Body depth             19.7-23.3  19.6-21.5
Caudal peduncle depth  13.0-14.9  13.1-14.4
Pre-dorsal length      70.5-73.1  71.4-72.9
Pre-pelvic length      55.0-57.4  53.6-57.1
Length of dorsal-fin   12.0-13.6  10.3-12.7
  base
Length of anal-fin     18.9-21.2  16.6-19.1
  base
Caudal-fin length      36.2-41.0  36.9-41.0
Pectoral-fin length    20.6-23.2  20.1-21.9
Pelvic-fin length       9.3-10.7   9.2-10.8
Head length            26.1-28.5  26.5-28.9
Percents of head length
Head depth             61.0-67.7  60.1-64.8
Head width             71.7-77.0  73.7-79.3
Snout length           11.9-15.1  12.3-16.3
Lower jaw length       19.3-23.5  19.8-21.9
Eye diameter           30.1-33.8  32.7-35.1
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