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Rays of the superorder Batoidea comprise the most diverse group of chondrichthyans in terms of valid species and morphological disparity. Up to the present little agreement is observed in studies based on morphological and molecular data focused on uncovering the interrelationships within Batoidea. Morphology-based phylogenies of batoids have not included characters related to the afferent branchial arteries, and little is known about the variation in this anatomical complex in rays. Herein, representatives of 32 genera from 19 families currently recognized of rays were examined as well as some shark taxa. Seven new characters are proposed and tested in two different analyses, one on their own and in the other they were added to the morphological data matrix of the most recent analysis of interrelationships within Batoidea. The arrangement of afferent branchial arteries differs mainly among orders and families of batoids. The absence of a common trunk from which the three posteriormost afferent arteries branch is interpreted as a synapomorphy for Myliobatiformes and the presence of a coronary cranial artery as an autapomorphy for Mobula hypostoma. A close spatial relationship between the second and third afferent arteries within the common branch from the ventral aorta is proposed as a synapomorphy for Rajiformes with a secondary modification in Sympterygia. Data about patterns in afferent branchial arteries in additional taxa such as Squaliformes and Chimaeriformes are needed to better understand the evolution of this character complex among chondrichthyans.

Made available in DSpace on 2022-04-28T19:42:09Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Instituto Chico Mendes de Conservação da Biodiversidade Universidad de La Frontera Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) A new species of miniature fish of the characid genus Priocharax is described from a small lake near the rio Ipixuna, rio Purus drainage, Amazonas State, Brazil. It is distinguished from all congeners except P. pygmaeus by the lower number of teeth on the maxilla and dentary. It differs from P. pygmaeus by the presence of two postcleithra and 22–27 branched anal-fin rays (vs absence and 19–22). The new species is further distinguished from other species of Priocharax by a combination of characters involving the number of pelvic-fin rays and branched anal-fin rays, the number of postcleithra, the shape of postcleithrum 3, and the absence of the claustrum. Molecular evidence based on COI sequences of all valid species of Priocharax also corroborates the validity of this new species. Laboratório de Ictiologia de Sorocaba Departamento de Biologia Universidade Federal de São Carlos – campus Sorocaba, Rod. João Leme dos Santos, km 110 Departamento de Biologia Estrutural e Funcional Instituto de Biociências Universidade Estadual Paulista – campus Botucatu, Rua Prof. Doutor Antonio Celso Wagner Zanin, 250 Departamento de Zoologia Instituto de Biociências Universidade de São Paulo, Rua do Matão, Travessa 14, 101 Departamento de Biologia Estrutural e Funcional Instituto de Biociências Universidade Estadual Paulista – campus Botucatu, Rua Prof. Doutor Antonio Celso Wagner Zanin, 250 FAPESP: 2014/26508–3 FAPESP: 2016/09204–6 FAPESP: 2017/06551–0 FAPESP: 2018/20610–1 CNPq: 306054/2006–0

A new species of the eleotrid genus Microphilypus from the Upper Rio Negro basin is described herein. It differs from all congeners in the presence of 5–6 arched rows of melanophores on the abdominal region, posterior to the base of the pelvic fins, followed by six large irregularly oval black blotches, with the tips of the three posteriormost blotches visible in lateral view; a dark teardrop-shaped blotch on the caudal peduncle, extending to the base of the ventral caudal rays; five light brown blotches along the dorsal profile of the body, between the origin of the second dorsal fin and the caudal peduncle; and the poorly developed laterosensory system on the head, with horizontal rows of head papillae b and d absent. A key to the species of Microphilypnus is presented.

Establishing phylogenetic relationships of miniature fishes is challenging in taxa with developmental truncation. Within the Characiformes, developmental truncation appears to be relatively rare, with the Neotropical genus Priocharax being an example. Priocharax includes three miniature species among the smallest of the order and has been hypothesized to belong to the Heterocharacinae. The pronounced reduction in its skeleton, however, prevented a clearer evaluation of its relationships. The present detailed osteological study was designed to address this question and revealed that 21 bones are absent and nine other skeletal structures are simplified in Priocharax when compared to other characids. Comparison of the skeleton of adult Priocharax with early developmental stages of other characids demonstrated that most of the absences and simplifications can be interpreted as developmental truncations. The most striking developmental truncations are in the pectoral girdle, in which the endoskeleton remains entirely cartilaginous. Other interesting truncations are in the ethmoid region of the skull, infraorbital series, and Weberian apparatus, in which the claustrum is absent. Our study also revealed some unusual sexual dimorphisms in the pelvic girdle. Two cladistic analyses were performed to assess the relationships of Priocharax within the Heterocharacinae. The first consisted of a traditional analysis in which all absences and reductions of Priocharax were coded in the same way as in the remaining taxa. This resulted in three equally most parsimonious topologies, all of which have Priocharax as the most basal taxon of the Heterocharacinae. The second analysis incorporated ontogenetic information, and most absences and reductions of Priocharax were reinterpreted as apomorphic conditions and thus, coded differently from similar conditions in outgroups. This resulted in a single phylogenetic hypothesis with Priocharax and Gnathocharax as sister groups based on seven synapomorphies. Our approach demonstrates the importance of developmental studies to better understand morphological evolution of miniaturized, truncated taxa, and to generate hypotheses of their relationships.

The taxonomy of Galeocharax, a genus of freshwater fishes distributed in most South American cis-Andean river systems, except the rio Negro, rio São Francisco and rio Xingu basins and the eastern drainages of Brazil, is herein revised. A total of 1229 specimens were examined from which 680 had meristic and morphometric data taken. Osteological and morphological features were also examined through radiographs, scanning electron microscopy and in cleared and stained specimens. Three of the four species previously considered as valid are herein recognized: Galeocharax humeralis from rio Paraguay and lower rio Paraná basins; Galeocharax goeldii, from rio Madeira basin, with records of geographical distribution expanded to the río Madre de Dios, río Beni, rio Mamoré and rio Guaporé basins and Galeocharax gulo, which is widespread throughout rio Amazonas, río Orinoco, rio Tocantins, and upper rio Paraná basins. Galeocharax knerii is herein considered a junior synonym of Galeocharax gulo. A key to species of Galeocharax is presented. RESUMO A taxonomia de Galeocharax, um gênero de peixes de água doce distribuído nos principais sistemas hídricos da América do Sul cisandina, com exceção da bacia do rio Negro, do rio São Francisco, do rio Xingu e das drenagens litorâneas do leste, é aqui revisada. Foram examinados 1229 exemplares, dos quais 680 tiveram dados merísticos e morfométricos tomados. Características osteológicas e morfológicas também foram examinadas por meio de radiografias, microscopia eletrônica de varredura e exemplares diafanizados. Três das quatro espécies previamente consideradas válidas são reconhecidas: Galeocharax humeralis das bacias do rio Paraguai e baixo rio Paraná; Galeocharax goeldii da bacia do rio Madeira, com registros de distribuição geográfica ampliados para as bacias dos rios Madre de Dios, Beni, Mamoré e Guaporé, e Galeocharax gulo amplamente distribuída nas bacias dos rios Amazonas, Orinoco, Tocantins e alto rio Paraná. Galeocharax knerii foi considerada sinônimo júnior de Galeocharax gulo. Uma chave de identificação para as espécies de Galeocharax é apresentada.

The Characinae is a subunit of the Characidae of special significance in including Charax, the type genus of the family and the order Characiformes. Twelve genera and 79 species have been traditionally assigned to the Characinae, but the subfamily still lacks a phylogenetic diagnosis. Herein, a data matrix including 150 morphological characters and 64 taxa (35 species representing all genera of the Characinae and 29 included in other lineages within the Characiformes) was submitted to two cladistic analyses that differ in the inclusion/exclusion of Priocharax due to the difficulty of coding most of the character states in the miniature species of this genus. Both analyses resulted in a non-monophyletic Characinae and this subfamily is herein restricted to only seven of the original 12 genera forming the clade (Phenacogaster((Charax Roeboides)(Acanthocharax(Cynopotamus(Acestrocephalus Galeocharax))))), which is supported by ten non-ambiguous synapomorphies and is more closely related to other genera of the Characidae than those traditionally placed in the subfamily. A second clade includes the members of the tribe Heterocharacini (Lonchogenys(Heterocharax Hoplocharax)) as the sister-group of Gnathocharax, supported by seven non-ambiguous synapomorphies. This clade is more closely related to a taxon formed by Roestes and Gilbertolus based on seven non-ambiguous synapomorphies. Results do not corroborate a close relationship between Roestes–Gilbertolus and the Cynodontinae. Inclusion of the genus Priocharax suggests that it is related more closely to the Heterocharacini, but the profound modifications in its anatomy possibly related to ontogenetic truncations obscure a better understanding of its relationships. A new classification of the Characinae and the Heterocharacinae is proposed. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 165, 809–915.

Acestrorhynchus is the sole genus of the family Acestrorhynchidae which includes 14 species currently recognized as valid. Species of Acestrorhynchus comprise small-to-medium sized piscivorous fishes and have been traditionally grouped on the basis of well-defined color patterns. A recent phylogeny, based on morphological characters, could not resolve the phylogenetic affinities of A. heterolepis and the relationships among the species of the clade formed by A. abbreviatus, A. altus, A. falcatus, A. lacustris, and A. pantaneiro. The simultaneous analysis of two mitochondrial genes (16S and ATP synthase subunits 6 and 8) and one nuclear intron (S7) was able to resolve the latter clade, but the position of A. heterolepis remained unresolved. The combination of the molecular and morphological data sets in a total evidence analysis resulted in a well-resolved hypothesis regarding the phylogenetic relationships of Acestrorhynchus species.

A total of 104 osteological and external morphological features were examined in 13 species of Acestrorhynchus and 15 outgroup taxa to advance a hypothesis of relationships within the genus. Two most parsimonious hypotheses corroborate the monophyly of Acestrorhynchus but differ in the hypothesized relationships of Acestrorhynchus heterolepis. Three proposed supraspecific assemblages are at least partially correlated with groups of species previously diagnosed on the basis of colour pattern: (1) Acestrorhynchus britskii, Acestrorhynchus grandoculis, Acestrorhynchus microlepis, and Acestrorhynchus minimus; (2) Acestrorhynchus falcirostris, Acestrorhynchus isalineae, and A. Acestrorhynchus nasutus; and (3) Acestrorhynchus abbreviatus, Acestrorhynchus altus, Acestrorhynchus falcatus, Acestrorhynchus lacustris, and Acestrorhynchus pantaneiro. In one hypothesis A. heterolepis is proposed as the closest relative of the clade formed by A. falcirostris, A. isalineae, and A. nasutus, and in the alternative hypothesis it is proposed as a sister species of the clade formed by A. abbreviatus, A. altus, A. falcatus, A. lacustris, and A. pantaneiro. Relationships among species of the latter clade remain unresolved. Two independent episodes of reduction of body size are hypothesized to have occurred within the genus: one associated with the clade formed by A. grandoculis and A. minimus, and the other with the clade formed by A. isalineae and A. nasutus. © 2007 The Linnean Society of London, Zoological Journal of the Linnean Society, 2007, 151, 691–757.

The taxonomy of the nominal species of giant trahiras Hoplias aimara (Valenciennes, 1846) and Hoplias macrophthalmus (Pellegrin, 1907), both described from Cayenne (French Guiana), was evaluated to determine whether they constitute distinct forms and to determine the geographic distribution of the recognized species. A total of 200 specimens were examined (30–624 mm standard length). Analysis of meristic and morphometric data resulted in the recognition of a single species. Study of the type-specimens revealed that both species names, H. aimara and H. macrophthalmus, refer to the same taxon. According to the Principle of Priority of the International Code of Zoological Nomenclature the name Hoplias aimara has precedence. This species is distinguished from congeners by the presence of a vertically-elongate dark spot on the median portion of the opercular membrane and by the absence of the accessory ectopterygoid. Hoplias aimara occurs in the drainages of Rio Tocantins, Rio Xingu, Rio Tapajos, Rio ...

A new Moenkhausia species is described from the middle rio Negro of Brazil. This species shares with Moenkhausia oligolepis, Moenkhausia sanctaefilomenae, and Moenkhausia pyrophthalma a reticulate body coloration and a red pigmentation on the dorsal margin of the eye. It can be distinguished from those species by the presence of a distinctive stripe on the caudal peduncle, a uniform anterior humeral blotch, and meristic and morphometric data. Priocharax ariel, Serrabrycon magoi, Microsternarchus fimbripinnus, and Acestridium martini are recorded for the first time from the middle rio Negro in Brazil.

Osteological features of cynodontine species and other characiforms were examined in order to investigate the monophyly of the Cynodontinae and the relationships among its species. A number of derived characters corroborated the hypothesis that the Cynodontinae and its three included genera Cynodon, Rhaphiodon, and Hydrolycus are monophyletic. Hydrolycus armatus is the sister group of H. tatauaia; H. scomberoides is the sister group of the clade formed by the latter two species; and H. wallacei is the sister group of the clade formed by H. armatus, H. tatauaia, and H. scomberoides. Rhaphiodon vulpinus is the sister group to Cynodon, and together they are the sister group to the clade formed by Hydrolycus species. Three Cynodon Agassiz, 1829, species are diagnosed. Cynodon gibbus Agassiz, 1829, occurs in the Rio Amazonas and Rio Orinoco basins, and the Rupununi River, Guyana. Cynodon meionactis Gery et al., 1999, occurs in the upper Maroni River, French Guiana, and C. septenarius, new species, occ...

The egg surface structure of Thalassophryne amazonica, a freshwater toadfish from the Amazon basin is described. Eggs of this species show a remarkable, highly unusual system of parallel ridges and intermittent grooves that originate at the equator of the egg and lead to the micropylar pit, at which they end in a spiralling pattern. A similar egg surface structure has so far been described only from a group of Asian anabantoid percomorphs, obviously not closely related to Thalassophryne. This egg surface pattern may enhance fertilization success by guiding sperm to the micropyle. We review museum records for T. amazonica, present an updated map of its occurrence in the Amazon basin, and provide information on its habitat. A estrutura da superfície do ovo de Thalassophryne amazonica um batracoidídeo de água doce da bacia amazônica é descrita. Os ovos dessa espécie apresentam um sistema notável e incomum de cristas paralelas e canais intermitentes, que se originam na porção equatorial do ovo e vão até a micrópila onde terminam em um padrão espiralado. Uma estrutura superficial de ovo semelhante foi até agora descrita apenas para um grupo de anabantóideos asiáticos, obviamente não relacionado a Thalassophryne. Esse padrão de superfície de ovo talvez aumente o sucesso da fertilização ao guiar o espermatozóide até à micrópila. Nós revisamos os registros de T. amazonica em museus, apresentamos um mapa atualizado de sua ocorrência na bacia Amazônica e fornecemos informações sobre seu habitat.

The taxonomic revision of the genus Lamontichthys Miranda-Ribeiro, based on the examination of 164 specimens of different river drainages throughout the Amazon basin, revealed the presence of six species of which two are new. Lamontichthys filamentosus occurs in the upper and middle portions of the rio Amazonas basin; L. llanero in the río Orinoco basin; L. maracaibero in the lago Maracaibo basin; and L. stibaros in the upper río Amazonas basin. Lamontichthys avacanoeiro, new species, occurs in the upper rio Tocantins basin; and L. parakana, new species, in the lower rio Tocantins basin. The new species represent a considerable extension in the so far known distribution of the genus. A parsimony analysis, including 87 osteological and external morphological characters from Lamontichthys and related taxa (total of 16), resulted in three most parsimonious trees with 194 steps (CI = 0.73 and RI = 0.78). The hypothesis of monophyly of Lamontichthys is corroborated and supported by six derived characters. Within Lamontichthys two monophyletic assemblages are recognized, one includes L. avacanoeiro and L. stibaros, the other includes L. maracaibero and the clade formed by L. filamentosus and L. llanero. The relationships of Lamontichthys parakana, a species that was not included in the phylogenetic analysis is discussed. The monophyly and relationships of the monotypic genus Pterosturisoma microps are also discussed. A revisão taxonômica do gênero Lamontichthys, realizada com base no exame de 164 exemplares de diversas drenagens da bacia amazônica, revelou a existência de seis espécies, das quais duas são novas. Lamontichthys filamentosus ocorre na bacia do alto e médio rio Amazonas; L. llanero, na bacia do rio Orinoco; L. maracaibero, na bacia do lago Maracaibo; e L. stibaros, na bacia do alto rio Amazonas. Lamontichthys avacanoeiro, espécie nova, ocorre na bacia do alto rio Tocantins e L. parakana, espécie nova, na bacia do baixo rio Tocantins. As novas espécies representam uma considerável ampliação da distribuição geográfica do gênero. Uma análise de parcimônia, incluindo 87 caracteres osteológicos e de morfologia externa de 16 táxons, incluindo Lamontichthys e grupos relacionados, resultou em três cladogramas mais parcimoniosos com 194 passos (CI = 0.73 and RI = 0.78). A hipótese de monofiletismo de Lamontichthys é corroborada e sustentada por seis sinapomorfias. Entre as espécies de Lamontichthys, dois grupos monofiléticos são reconhecidos, um incluindo L. avacanoeiro e L. stibaros e outro L. maracaibero e um clado formado por L. filamentosus e L. llanero. A relação de Lamontichthys parakana com as demais espécies do gênero é discutida, apesar da espécie não ter sido incluída na análise filogenética. O monofiletismo e as relações do gênero monotípico Pterosturisoma microps são também discutidos.

The Neotropical characid fishes of the genus Chalceus Cuvier, 1817, are reviewed. In total, five species are recognized (including three new species). Chalceus epakros sp. nov. is the most widespread geographically, occurring in many rivers of the Amazon basin, the Rio Orinoco and in the Essequibo River drainage in Guyana. Chalceus guaporensis sp. nov. is restricted to the upper Rio Madeira, Rio Guapore and Rio Madre de Dios, of Brazil, Bolivia and Peru, respectively. Chalceus spilogyros sp. nov. occurs only in the Rio Trombetas, lower Rio Tapajos and lower Rio Madeira drainages. Chalceus macrolepidotus Cuvier occurs in the Rio Negro drainage, middle and lower Rio Orinoco basin and in the rivers of the Atlantic slopes of the Guianas, and Chalceus erythrurus Cope in the Rio Amazonas and Rio Solimoes to Rio Ucayali drainage in Peru. Chalceus ararapeera Cuvier & Valenciennes and Creagrutus pellegrini Puyo are considered synonyms of C. macrolepidotus, and Pellegrinina heterolepis Fowler is placed into the synonymy of C. erythrurus. Characters pertaining to the monophyly of Chalceus are discussed and a key to species is presented. © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society, 2004, 140, 103−135.

Priocharax nanus, new species, is described from the rio Negro, Brazil. It is a miniature fish that retains as an adult the larval rayless pectoral fin, a diagnostic character of the genus. Priocharax nanus possesses fewer reductive features compared to congeners, P. ariel and P. pygmaeus, from which it can be distinguished by the presence of i,6 pelvic-fin rays ( vs. i,5), the presence of the claustrum (vs. claustrum absent) and the presence of two postcleithra (vs. postcleithra absent). An updated list of 213 species of miniature Neotropical freshwater fishes is presented. The greatest diversity among them is represented by the Characiformes with 87 miniature species. Priocharax nanus, especie nova, e descrita do rio Negro, Brasil. E um peixe miniatura que retem no adulto a forma larval da nadadeira peitoral, um carater diagnostico do genero. Priocharax nanus possui um numero menor de caracteres redutivos quando comparado aos congeneres, P. ariel and P. pygmaeus, dos quais pode ser distinguida pela presenca de i,6 raios na nadadeira pelvica (vs. i,5), presenca do claustrum (vs. claustrum ausente) e presenca de dois pos-cleitros (vs. pos-cleitros ausentes). Uma lista atualizada de 213 especies de peixes miniatura de agua doce neotropicais e apresentada. A maior diversidade entre eles e representada pelos Characiformes, com 87 especies miniatura.