Branching patterns of the afferent branchial arteries and their phylogenetic significance in rays (Batoidea).

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.

A new miniature species of Priocharax (Characiformes: Characidae) from the upper rio Ipixuna, Purus drainage, Brazil

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.(AU)

Uma nova espécie de peixe miniatura do gênero de caracídeo Priocharax é descrita de um pequeno lago próximo ao rio Ipixuna, drenagem do rio Purus, estados do Amazonas, Brasil. Ela difere de todas as congêneres, exceto P. pygmaeus pelo menor número de dentes no maxilar e dentário. Distingue-se de P. pygmaeus pela presença de dois pós-cleitros e 22-27 raios ramificados na nadadeira anal (vs ausência e 19-22). A nova espécie também difere de outras congêneres por uma combinação de caracteres como número de raios das nadadeiras pélvica e anal, número de pós-cleitros e formato do pós-cleitro 3, e ausência de claustrum. Evidências moleculares com base em sequências do gene COI de todas as espécies válidas também corrobora a validade da nova espécie.(AU)

Taxonomic review of the pipefish genus Pseudophallus Herald, with the description of a new species (Syngnathiformes: Syngnathidae).

We present a taxonomic review of the genus Pseudophallus, based on morphological characters, originally described to include two freshwater pipefish species from the Pacific coastal drainages of the neotropics: P. starksii and P. elcapitanensis, with the later addition of P. mindii, described from Atlantic coastal drainages. Pseudophallus mindii was formerly recognized as a single species ranging from the Brazilian state of São Paulo to Belize in Central America. Five species are recognized in the present study: P. elcapitanensis and P. starksii from the Pacific drainages; P. mindii and P. brasiliensis, the latter so far considered a junior synonym of P. mindii, and a new species. Pseudophallus mindii is redefined to include specimens with higher meristic values and narrow range of variation compared to P. brasiliensis and is restricted to the northern coastal drainages from Venezuela to Central America including the Caribbean region. Pseudophallus brasiliensis is revalidated and occurs from the drainages east of the mouth of the Orinoco to southern Brazil. The new species, Pseudophallus galadrielae sp. nov. is endemic to Lago Izabal in Guatemala. An updated identification key to the currently recognized species is provided.

Taxonomic study of Moenkhausia cotinho Eigenmann, 1908 and Hemigrammus newboldi (Fernández-Yépez, 1949) with the description of two new species of Moenkhausia (Teleostei: Characiformes: Characidae).

Moenkhausia cotinho is redescribed based on the examination of meristic and morphometric data and external morphological characters of specimens from the Amazon and Orinoco basins and from rivers in the Guyana. The species is distinguished from congeners based on the combination of a reticulate color pattern, the presence of dark spots on the posterior edge of scales of the longitudinal rows dorsal to the lateral line, the presence of a dark blotch on the caudal-fin base failing to reach the posterior tip of the middle caudal-fin rays; the dorsal region of the eyes red to orange in life; 5/3 longitudinal series of scales, above and below the lateral line, respectively; and the tips of the pectoral-fin rays not extending beyond the base of the pelvic fin. All specimens of M. cotinho have a completely pored literal line except for a few specimens from drainages in the Guyana. The redefinition of the taxonomic limits and geographic distribution of M. cotinho allowed us to reevaluate the taxonomic limits and geographic distribution of Hemigrammus newboldi, the identity of which has been previously questioned, but which is clearly diagnosed from M. cotinho based on the relatively longer pectoral fin, the presence of conical teeth in the posterior portion of the dentary, the absence of a reticulate color pattern of body and in the shorter longitudinal dark stripe on body. In addition, two new species of Moenkhausia are described: Moenkhausia rondoni sp n. from the rio Madeira basin, Brazil and Moenkhausia pirahan sp n. from the lower rio Madeira and rio Trombetas and rio Tapajós basins, Brazil.

Taxonomic revision of Galeocharax (Characiformes: Characidae: Characinae)

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.(AU)

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.(AU)

Osteology of Priocharax and remarkable developmental truncation in a miniature Amazonian fish (Teleostei: Characiformes: Characidae).

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.

Priocharax nanus, a new miniature characid from the rio negro, Amazon basin (ostariophysi: characiformes), with an updated list of miniature neotropical freshwater fishes

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, espécie nova, é descrita do rio Negro, Brasil. É um peixe miniatura que retém no adulto a forma larval da nadadeira peitoral, um caráter diagnóstico do gênero. Priocharax nanus possui um número menor de caracteres redutivos quando comparado aos congêneres, P. ariel and P. pygmaeus, dos quais pode ser distinguida pela presença de i,6 raios na nadadeira pélvica (vs. i,5), presença do claustrum (vs. claustrum ausente) e presença de dois pós-cleitros (vs. pós-cleitros ausentes). Uma lista atualizada de 213 espécies de peixes miniatura de água doce neotropicais é apresentada. A maior diversidade entre eles é representada pelos Characiformes, com 87 espécies miniatura.

Egg surface structure of the freshwater toadfish Thalassophryne amazonica (Teleostei: Batrachoididae) with information on its distribution and natural habitat

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.

Phylogeny of the Neotropical genus Acestrorhynchus (Ostariophysi: Characiformes) based on nuclear and mitochondrial gene sequences and morphology: a total evidence approach.

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.

Systematics of Lamontichthys Miranda-Ribeiro (Siluriformes: Loricariidae), with the description of two new species

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.(AU)

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.(AU)