Molecular phylogenetics of Neotropical detritivorous fishes of the family Curimatidae (Teleostei: Characiformes).

Curimatidae, the fourth largest family of detritivorous Neotropical characiform fishes, encompasses eight extant genera and over 110 species dwelling in diverse freshwater habitats from Costa Rica to Argentina. Extensive phylogenetic analyses of soft anatomy and osteology provided evidence for intergeneric and most interspecific relationships, and formed the basis of curimatid taxonomy for nearly 40 years. However, that morphological phylogeny demonstrated incomplete phylogenetic resolution at various scales and has never been tested with extensive molecular data. Herein, we infer molecular phylogenies spanning ∼70% of the known species diversity using three nuclear and three mitochondrial loci. Topologies from concatenated likelihood and Bayesian analyses and coalescent Bayesian species trees agree broadly with each other, and with the prior morphological hypothesis in many, but not all respects. All molecular analyses support the monophyly of Curimatidae and of six of its constituent genera, and agree on the placement of Curimatopsis as sister to all other curimatids. DNA-based intergeneric relationships differ substantially from prior morphological hypotheses by placing Curimata sister to Potamorhina and Psectrogaster sister to Pseudocurimata, rather than in a ladderized arrangement. Our results also resolve a major uncertainty in the morphological tree by revealing Cyphocharax, a genus for which no anatomical synapomorphy has ever been proposed, as a paraphyletic assemblage containing a monophyletic Steindachnerina and a polyphyletic Curimatella. Overall, the phylogeny expands substantially our understanding of the morphology, phylogenetics and evolution of the Curimatidae, and will guide future intrageneric studies by improving precision in the choice of comparative taxa.

Trophic evolution in African citharinoid fishes (Teleostei: Characiformes) and the origin of intraordinal pterygophagy.

The African freshwater suborder Citharinoidei (Characiformes) includes 110 species that exhibit a diversity of feeding modes comparable to those characteristic of more speciose groups such its sister, the Characoidei (2000+ species) or the distantly related Cichlidae (1600+ species). Feeding habits of the Citharinoidei range from generalist omnivores to highly specialized feeding modes including ectoparasitic fin-eating, i.e. pterygophagy. We examine diet preference evolution in the Citharinoidei using newly inferred multi-gene-based hypotheses of phylogenetic relationships for representatives of 12 of the 15 genera in the suborder. Ancestral character state reconstructions onto our best tree indicate that the three most-generalist diets - pelophage/planktivore, omnivore and invertivore - are also the most primitive conditions within the Citharinoidei. The feeding mode of the most recent common ancestor of the Citharinoidei was characterized by high uncertainty. The more specialized feeding habits - herbivory, piscivory and pterygophagy - originated later in the Citharinoidei, likely from invertivore ancestors and possibly across a short time period. Highly specialized fin eaters (Belonophago, Phago and Eugnatichthys) share a common origin along with a strict piscivore (Mesoborus) and an invertivore (Microstomatichthyoborus). The largely piscivorous, but facultative fin eater, Ichthyborus is not exclusively related to them. Our results demonstrate that overall diet preference transitions in the Citharinoidei were rare events with very few reversals or parallelisms, and that evolutionary shifts in trophic ecology have not played a major role in intraordinal diversification. This situation contrasts with other groups in which dietary transitions have played key roles in species diversification.

Herbivory Promotes Dental Disparification and Macroevolutionary Dynamics in Grunters (Teleostei: Terapontidae), a Freshwater Adaptive Radiation.

Trophic shifts into new adaptive zones have played major (although often conflicting) roles in reshaping the evolutionary trajectories of many lineages. We analyze data on diet, tooth, and oral morphology and relate these traits to phenotypic disparification and lineage diversification rates across the ecologically diverse Terapontidae, a family of Australasian fishes. In contrast to carnivores and most omnivores, which have retained relatively simple, ancestral caniniform tooth shapes, herbivorous terapontids appear to have evolved a variety of novel tooth shapes at significantly faster rates to meet the demands of plant-based diets. The evolution of herbivory prompted major disparification, significantly expanding the terapontid adaptive phenotypic continuum into an entirely novel functional morphospace. There was minimal support for our hypothesis of faster overall rates of integrated tooth shape, spacing, and jaw biomechanical evolution in herbivorous terapontids in their entirety, compared with other trophic strategies. There was, however, considerable support for accelerated disparification within a diverse freshwater clade containing a range of specialized freshwater herbivores. While the evolutionary transition to herbivorous diets has played a central role in terapontid phenotypic diversification by pushing herbivores toward novel fitness peaks, there was little support for herbivory driving significantly higher lineage diversification compared with background rates across the family.

Molecular phylogenetics of the Neotropical fish family Prochilodontidae (Teleostei: Characiformes).

Migratory detritivores of the characiform family Prochilodontidae occur throughout the freshwaters of much of South America. Prochilodontids often form massive populations and many species achieve substantial body sizes; a combination that makes them one of the most commercially important fish groups on the continent. Their economic significance notwithstanding, prochilodontids have never been the subject of a comprehensive molecular phylogenetic analysis. Using three mitochondrial and three nuclear loci spanning all prochilodontid species, we generated a novel phylogenetic hypothesis for the family. Our results strongly support monophyly of the family and the three included genera. A novel, highly supported placement of Ichthyoelephas sister to the clade containing Prochilodus and Semaprochilodus diverges from a previous morphological hypothesis. Most previously hypothesized interspecific relationships are corroborated and some longstanding polytomies within Prochilodus and Semaprochilodus are resolved. The morphologically similar P. brevis, P. lacustris, P. nigricans and P. rubrotaeniatus are embedded within what is herein designated as the P. nigricans group. Species limits and distributions of these species are problematic and the group clearly merits taxonomic revision.

A morphological supermatrix-based phylogeny for the Neotropical fish superfamily Anostomoidea (Ostariophysi: Characiformes): phylogeny, missing data and homoplasy.

Although 11 studies have addressed the systematics of the four families and 281 fish species of the ecomorphologically diverse Anostomoidea, none has proposed a global hypothesis of relationships. We synthesized these studies to yield a supermatrix with 463 morphological characters among 174 ingroup species, and inferred phylogeny with parsimony and Bayesian optimization. We evaluated the applicability of the supermatrix approach to morphological datasets, tested its sensitivity to missing data, determined the impact of homoplastic characters on phylogenetic resolution, and determined the distribution of homologies and homoplasies on the topology. Despite more than 60% missing data, analyses supported the monophyly of all families, and phylogenetic structure degraded only with inclusion of species with high percentages of missing data and in analyses limited to homoplasies. The latter differs modestly from the full matrix indicating phylogenetic signal in homoplastic characters. Character distributions differ across the phylogeny, with a greater prevalence of homologies at deeper nodes and homoplasies nearer the tips than expected by chance. This may suggest early diversification into distinct bauplans with subsequent diversification of faster evolving character systems. The morphological supermatrix approach is powerful and allows integration of classical data with modern methods to examine the evolution of multiple character systems.

The first molecular phylogeny of Chilodontidae (Teleostei: Ostariophysi: Characiformes) reveals cryptic biodiversity and taxonomic uncertainty.

Chilodontidae is a small family of eight described characiform species popularly known as headstanders. These small to moderately sized fishes are well known to aquarists, who prize their striking spotted pigmentation and unusual behaviors, and to systematists, who have revised both chilodontid genera in recent memory and studied their phylogenetic relationships using a comprehensive morphological dataset. However, no molecular phylogeny for the family has ever been proposed. Here, we reconstruct phylogenetic relationships for all eight known chilodontid species using three mitochondrial and two nuclear loci. Results largely agree with the previous morphological hypothesis, and confirm the monophyly of the family as well as its included genera, Caenotropus and Chilodus. The molecular topology differs slightly from the morphological hypothesis by placing Caenotropus maculosus rather than C. mestomorgmatos as the sister to the remaining three congeners, and by reconstructing the Curimatidae as the closest outgroup family, rather than the Anostomidae. However, the topologies supported by the morphological data were only slightly less likely and could not be rejected via Shimodaira-Hasegawa tests. Within Chilodus, two described species with distinctive pigmentation (C. fritillus and C. zunevei) appear embedded within the broad distributed C. punctatus clade, suggesting the presence of cryptic taxa with polymorphic pigmentation within the present concept of C. punctatus. Future work should combine morphological and molecular data to revisit the taxonomy and systematics of Chilodus and determine species limits within the C. punctatus-group sensu lato.

Phylogenetic relationships within the speciose family Characidae (Teleostei: Ostariophysi: Characiformes) based on multilocus analysis and extensive ingroup sampling.

BACKGROUND: With nearly 1,100 species, the fish family Characidae represents more than half of the species of Characiformes, and is a key component of Neotropical freshwater ecosystems. The composition, phylogeny, and classification of Characidae is currently uncertain, despite significant efforts based on analysis of morphological and molecular data. No consensus about the monophyly of this group or its position within the order Characiformes has been reached, challenged by the fact that many key studies to date have non-overlapping taxonomic representation and focus only on subsets of this diversity. RESULTS: In the present study we propose a new definition of the family Characidae and a hypothesis of relationships for the Characiformes based on phylogenetic analysis of DNA sequences of two mitochondrial and three nuclear genes (4,680 base pairs). The sequences were obtained from 211 samples representing 166 genera distributed among all 18 recognized families in the order Characiformes, all 14 recognized subfamilies in the Characidae, plus 56 of the genera so far considered incertae sedis in the Characidae. The phylogeny obtained is robust, with most lineages significantly supported by posterior probabilities in Bayesian analysis, and high bootstrap values from maximum likelihood and parsimony analyses. CONCLUSION: A monophyletic assemblage strongly supported in all our phylogenetic analysis is herein defined as the Characidae and includes the characiform species lacking a supraorbital bone and with a derived position of the emergence of the hyoid artery from the anterior ceratohyal. To recognize this and several other monophyletic groups within characiforms we propose changes in the limits of several families to facilitate future studies in the Characiformes and particularly the Characidae. This work presents a new phylogenetic framework for a speciose and morphologically diverse group of freshwater fishes of significant ecological and evolutionary importance across the Neotropics and portions of Africa.

Phylogenomic incongruence, hypothesis testing, and taxonomic sampling: The monophyly of characiform fishes.

Phylogenomic studies using genome-wide datasets are quickly becoming the state of the art for systematics and comparative studies, but in many cases, they result in strongly supported incongruent results. The extent to which this conflict is real depends on different sources of error potentially affecting big datasets (assembly, stochastic, and systematic error). Here, we apply a recently developed methodology (GGI or gene genealogy interrogation) and data curation to new and published datasets with more than 1000 exons, 500 ultraconserved element (UCE) loci, and transcriptomic sequences that support incongruent hypotheses. The contentious non-monophyly of the order Characiformes proposed by two studies is shown to be a spurious outcome induced by sample contamination in the transcriptomic dataset and an ambiguous result due to poor taxonomic sampling in the UCE dataset. By exploring the effects of number of taxa and loci used for analysis, we show that the power of GGI to discriminate among competing hypotheses is diminished by limited taxonomic sampling, but not equally sensitive to gene sampling. Taken together, our results reinforce the notion that merely increasing the number of genetic loci for a few representative taxa is not a robust strategy to advance phylogenetic knowledge of recalcitrant groups. We leverage the expanded exon capture dataset generated here for Characiformes (206 species in 23 out of 24 families) to produce a comprehensive phylogeny and a revised classification of the order.

Unexpected species diversity in electric eels with a description of the strongest living bioelectricity generator.

Is there only one electric eel species? For two and a half centuries since its description by Linnaeus, Electrophorus electricus has captivated humankind by its capacity to generate strong electric discharges. Despite the importance of Electrophorus in multiple fields of science, the possibility of additional species-level diversity in the genus, which could also reveal a hidden variety of substances and bioelectrogenic functions, has hitherto not been explored. Here, based on overwhelming patterns of genetic, morphological, and ecological data, we reject the hypothesis of a single species broadly distributed throughout Greater Amazonia. Our analyses readily identify three major lineages that diverged during the Miocene and Pliocene-two of which warrant recognition as new species. For one of the new species, we recorded a discharge of 860 V, well above 650 V previously cited for Electrophorus, making it the strongest living bioelectricity generator.

Data on the multilocus molecular phylogenies of the Neotropical fish family Prochilodontidae (Teleostei: Characiformes).

The data presented herein support the article "Molecular phylogenetics of the Neotropical fish family Prochilodontidae (Teleostei: Characiformes)" (B.F. Melo, B.L. Sidlauskas, B.W. Frable, K. Hoekzema, R.P. Vari, C. Oliveira, 2016) [1], which inferred phylogenetic relationships of the prochilodontids from an alignment of three mitochondrial and three nuclear loci (5279 bp) for all 21 recognized prochilodontid species and 22 related species. Herein, we provide primer sequences, museum voucher information and GenBank accession numbers. Additionally, we more fully describe the maximum-likelihood and Bayesian phylogenetic analyses of the concatenated dataset, detail the Bayesian species tree analysis, and provide the maximum likelihood topologies congruent with prior morphological hypotheses that were compared with the unconstrained tree using Shimodaira-Hasegawa tests.

VARSEDIG: an algorithm for morphometric characters selection and statistical validation in morphological taxonomy.

We present and discuss VARSEDIG, an algorithm which identifies the morphometric features that significantly discriminate two taxa and validates the morphological distinctness between them via a Monte-Carlo test. VARSEDIG is freely available as a function of the RWizard application PlotsR (http://www.ipez.es/RWizard) and as R package on CRAN. The variables selected by VARSEDIG with the overlap method were very similar to those selected by logistic regression and discriminant analysis, but overcomes some shortcomings of these methods. VARSEDIG is, therefore, a good alternative by comparison to current classical classification methods for identifying morphometric features that significantly discriminate a taxon and for validating its morphological distinctness from other taxa. As a demonstration of the potential of VARSEDIG for this purpose, we analyze morphological discrimination among some species of the Neotropical freshwater family Characidae.

Development of the splanchnocranium in Prochilodus argenteus (Teleostei: Characiformes) with a discussion of the basal developmental patterns in the Otophysi.

Development of the mandibular, hyoid and gill arches, which constitute the splanchnocranium, are described for Prochilodus argenteus, order Characiformes, one of the basal lineages of the Otophysi. Development was examined from just hatched larvae through juveniles using whole specimens cleared and counterstained for cartilage and bone as well as histological preparations. Observations are compared with the developmental trends reported for Cypriniformes, the basalmost clade of the Otophysi. Shortened developmental sequences for Prochilodus compared to the cypriniform Catostomus were discovered in the ontogeny of the ceratohyals, ceratobranchials 1-5, epibranchials 1-4 and the symplectic portion of the hyosymplectic. Prochilodus also differs from Catostomus in having the basihyal plus the anterior copula appearing at different stages of ontogeny rather than simultaneously. Contrary to previous assumptions, developmental information indicates that hypobranchial 4 as well as likely basibranchial 5 are present in Prochilodus. Various developmental patterns in Prochilodus considered basal for the Otophysi, the predominant component of the Ostariophysi, are likely conserved from patterns prevalent in basal groups in the Actinopterygii.

The jaw adductor muscle complex in teleostean fishes: evolution, homologies and revised nomenclature (osteichthyes: actinopterygii).

The infraclass Teleostei is a highly diversified group of bony fishes that encompasses 96% of all species of living fishes and almost half of extant vertebrates. Evolution of various morphological complexes in teleosts, particularly those involving soft anatomy, remains poorly understood. Notable among these problematic complexes is the adductor mandibulae, the muscle that provides the primary force for jaw adduction and mouth closure and whose architecture varies from a simple arrangement of two segments to an intricate complex of up to ten discrete subdivisions. The present study analyzed multiple morphological attributes of the adductor mandibulae in representatives of 53 of the 55 extant teleostean orders, as well as significant information from the literature in order to elucidate the homologies of the main subdivisions of this muscle. The traditional alphanumeric terminology applied to the four main divisions of the adductor mandibulae - A1, A2, A3, and Aω - patently fails to reflect homologous components of that muscle across the expanse of the Teleostei. Some features traditionally used as landmarks for identification of some divisions of the adductor mandibulae proved highly variable across the Teleostei; notably the insertion on the maxilla and the position of muscle components relative to the path of the ramus mandibularis trigeminus nerve. The evolutionary model of gain and loss of sections of the adductor mandibulae most commonly adopted under the alphanumeric system additionally proved ontogenetically incongruent and less parsimonious than a model of subdivision and coalescence of facial muscle sections. Results of the analysis demonstrate the impossibility of adapting the alphanumeric terminology so as to reflect homologous entities across the spectrum of teleosts. A new nomenclatural scheme is proposed in order to achieve congruence between homology and nomenclature of the adductor mandibulae components across the entire Teleostei.

The untold story of the caudal skeleton in the electric eel (ostariophysi: gymnotiformes: electrophorus).

Alternative hypotheses had been advanced as to the components forming the elongate fin coursing along the ventral margin of much of the body and tail from behind the abdominal region to the posterior margin of the tail in the Electric Eel, Electrophorus electricus. Although the original species description indicated that this fin was a composite of the caudal fin plus the elongate anal fin characteristic of other genera of the Gymnotiformes, subsequent researchers proposed that the posterior region of the fin was formed by the extension of the anal fin posteriorly to the tip of the tail, thereby forming a "false caudal fin." Examination of ontogenetic series of the genus reveal that Electrophorus possesses a true caudal fin formed of a terminal centrum, hypural plate and a low number of caudal-fin rays. The confluence of the two fins is proposed as an additional autapomorphy for the genus. Under all alternative proposed hypotheses of relationships within the order Gymnotiformes, the presence of a caudal fin in Electrophorus optimized as being independent of the occurence of the morphologically equivalent structure in the Apteronotidae. Possible functional advantages to the presence of a caudal fin in the genus are discussed.

Protocheirodon, a new genus of Characidae (Teleostei: Characiformes) with the redescription of the poorly known protocheirodon pi

Protocheirodon, a new genus of the Characidae, is proposed to include a species previously assigned to Leptagoniates . This action is supported by molecular and morphological phylogenetic hypotheses that place Protocheirodon pi as the sister group of the remaining tribes in the Cheirodontinae versus the traditional assignment of the species to the Aphyocharacinae. The phylogenetic position of Protocheirodon is recognized as a new tribe, the Protocheirodontini. Protocheirodon pi , originally described based on a small number of specimens from a single location in the río Mamoré basin in the southwestern Amazon, is redescribed on the basis of larger series of specimens from the western and central portions of the Amazon basin.

Protocheirodon, um gênero novo de Characidae é proposto para incluir uma espécie previamente alocada em Leptagoniates . Esta decisão é suportada por hipóteses filogenéticas moleculares e morfológicas que apontam Protocheirodon pi como grupo-irmão das demais tribos de Cheirodontinae, ao invés da alocação tradicional em Aphyocharacinae. A posição filogenética de Protocheirodon é reconhecida como uma tribo nova, Protocheirodontini. Protocheirodon pi , originalmente descrito com base em poucos exemplares de uma única localidade na bacia do rio Mamoré, no sudoeste da Amazônia, é redescrito com base em grandes séries de espécimes coletados em rios das porções centrais e ocidentais da bacia do rio Amazonas.

New species of cyphocharax (characiformes: curimatidae) from the upper rio Negro, Amazon basin

A new species of Cyphocharax, Curimatidae, apparently endemic to the blackwater upper rio Negro of the Amazon basin in northern Brazil, is described. The new species is readily distinguished from its congeners by the presence of a distinctly longitudinally elongate, posteriorly vertically expanding patch of dark pigmentation along the midlateral surface of the caudal peduncle, with the patch extending from the base of the middle caudal-fin rays anteriorly past the vertical through the posterior terminus of the adipose fin. The new species additionally differs from all congeners in details of body and fin pigmentation and meristic and morphometric ratios. Evidence for the assignment of the species to Cyphocharax and the occurrence of other species of the Curimatidae apparently endemic to the upper rio Negro catchment is discussed.

Uma espécie nova de Cyphocharax, Curimatidae, aparentemente endêmica das águas escuras do rio Negro, bacia amazônica no norte do Brasil, é descrita. A espécie nova é prontamente distinguida de suas congêneres pela presença de uma mancha escura distintamente alongada longitudinalmente e posteriormente expandida na vertical ao longo da superfície lateral do pedúnculo caudal, sendo estendida da base dos raios medianos da nadadeira caudal até a linha vertical do término da nadadeira adiposa. Adicionalmente, a espécie nova difere de todas as congêneres nos detalhes do corpo, pigmentação das nadadeiras e nas proporções merísticas e morfométricas. As evidências para alocação da espécie no gênero Cyphocharax e a ocorrência de outras espécies de Curimatidae aparentemente endêmicas do alto rio Negro são discutidas.

New species of the catfish genus Tatia (Siluriformes: Auchenipteridae) from the rio Teles Pires, upper rio Tapajós basin, Brazil

Analysis of specimens of the auchenipterid catfish genus Tatia collected in the rio Teles Pires, a tributary of the rio Tapajós, along the border between the states of Pará and Mato Grosso, Brazil, revealed it to be an undescribed species. This new species is distinguished from all congeners with the exception of T. carolae and T. musaica by the intense, clearly demarcated, dark coloration on the dorsal and to varying degrees lateral and sometimes ventrolateral portions of the body versus the very lightly colored regions which are translucent in life on the remainder of the body. Various details of head, body and dorsal and caudal-fin pigmentation along with meristic and morphometric features distinguish the new species from T. carolae and T. musaica. The new species provides further evidence that the upper and middle rio Tapajós is a region of ichthyofaunal endemism.

A análise de espécimes do bagre auquenipterídeo do gênero Tatia, provenientes do rio Teles Pires, um tributário do rio Tapajós, na divisa entre os estados do Pará e Mato Grosso, Brasil, revelou se tratar de uma espécie ainda não descrita. Esta espécie nova distingue-se de seus congêneres, com exceção de T. carolae e T. musaica, por sua intensa e distintamente demarcada, coloração escura sobre o dorso a variados graus na porção lateral e algumas vezes ventro-lateral do corpo em contraste com regiões de coloração muito clara, a qual é translúcida em vida, no restante do corpo. Vários detalhes da pigmentação da cabeça, corpo, e nadadeira caudal e dorsal juntamente com características merísticas e morfométricas distinguem a espécie nova de T. carolae e T. musaica. A espécie nova fornece evidência adicional de que a porção alta e média da bacia do rio Tapajós é uma região de endemismo da ictiofauna.

Miniature catfishes of the genus Gelanoglanis (Siluriformes: Auchenipteridae): monophyly and the description of a new species from the upper rio Tapajós basin, Brazil

Previously proposed synapomorphies for the genus Gelanoglanis of the catfish family Auchenipteridae are evaluated and four additional features involving the relationship between the mesethmoid and premaxilla, the very fleshy anterior portion of the snout, the lack of ossification of the second through fourth infraorbitals, and the incomplete poring of the lateral line are hypothesized as synapomorphic for the members of the genus. A new species of Gelanoglanis is described based on a series of specimens collected in the rio Teles Pires, a tributary of the rio Tapajós in the southern reaches of the Amazon basin. The new species demonstrates a number of features unusual within Gelanoglanis including a fontanel bordered by the frontals, a particularly elongate gonopodium in mature males, reductions in the dentition on the premaxilla, and a shorter posterior extension of the maxilla inside the maxillary barbel. The new species is a miniature as evidenced both by its body size and the reductions of various ossifications of the head, the number of fin rays and of the laterosensory canal system on the head and body. Sinapomorfias propostas previamente para o gênero Gelanoglanis da família Auchenipteridae são avaliadas e quatro características adicionais que envolvem a relação entre o mesetmóide e a pré-maxila, a porção anterior do focinho carnosa, a perda de ossificação do segundo ao quarto infraorbital e linha lateral incompleta são hipotetizadas como sinapomórficas para os membros do gênero. Uma espécie nova de Gelanoglanis é descrita com base em uma série de exemplares coletados no rio Teles Pires, um tributário do rio Tapajós na porção sul da bacia Amazônica. A espécie nova possui várias características incomuns dentro de Gelanoglanis, incluindo uma fontanela bordeada pelos frontais, um gonopódio particularmente longo em machos maduros, redução da dentição na premaxila, e extensão posterior da maxila mais curta dentro do barbilhão maxilar. A espécie nova é uma miniatura, como evidenciado não apenas pelo tamanho reduzido do corpo, como também pela redução da ossificação da cabeça, do número de raios e do sistema de canais látero-sensoriais da cabeça e do tronco.

Review of the andean armored catfishes of the genus Dolichancistrus Isbrücker (Siluriformes: Loricariidae)

The loricariid catfish genus Dolichancistrus is reviewed and four species recognized. Species of Dolichancistrus are distinguished from each other by the degree of development of the pectoral-fin spine, the form of the distal margin of the pelvic fin, the relative size and form of the cheek plates, the pattern of odontodes along the margin of the snout, the presence versus absence of a buccal papilla at the premaxillary symphysis, and the relative lengths of the anal- versus pelvic-spines. Dolichancistrus atratoensis is known from the río Atrato system and the río Cubarradó on the Pacific versant of Colombia; D. carnegiei occurs in the eastern río Magdalena basin in the departments of Boyacá and Santander, Colombia; D. cobrensis inhabits southern tributaries of the Lago Maracaibo basin in Colombia and Venezuela along with some highland rivers of the Cordillera de Mérida in Venezuela draining into the río Orinoco system; and D. fuesslii is known from the Andean piedmont portions of the río Meta basin in the western río Orinoco system. Pseudancistrus pediculatus is considered a junior synonym of Ancistrus fuesslii. Chaetostomus setosus previously assigned to Dolichancistrus, was found to lack features characteristic of its putative congeners and is rather more closely related to other members of Chaetostoma group. Consequently, the species is herein considered as incertae sedis within that group. Dolichancistrus is diagnosed, a key is provided to the members of the genus, and diagnoses and redescriptions are provided for all of the recognized species.

Se presenta una revisión del género Dolichancistrus y se reconocen cuatro especies válidas. Las especies de Dolichancistrus se distinguen entre sí a partir del grado de desarrollo de la espina pectoral, la forma del margen distal de la aleta pélvica, el tamaño relativo y la forma de las placas operculares, el patrón de odontoides a lo largo del margen del hocico, la presencia versus ausencia de papila bucal en la sínfisis de las premaxilas, y las longitudes relativas de las espinas anal y pélvicas. Dolichancistrus atratoensis es conocido del sistema del río Atrato y del río Cubarradó sobre la vertiente Pacífico de Colombia; D. carnegiei se encuentra en la vertiente Oriental de la cuenca del río Magdalena en los departamentos de Boyacá y Santander, Colombia; D. cobrensis habita los tributarios sureños de la cuenca del Lago Maracaibo en Colombia y Venezuela así como en algunos ríos de alta montaña de la Cordillera de Mérida en Venezuela drenando hacia el sistema del río Orinoco; y D. fuesslii es conocido de porciones pedimontanas Andinas de la cuenca del río Meta en la región occidental del sistema del río Orinoco. Pseudancistrus pediculatus es considerado un sinónimo junior de Ancistrus fuesslii. Chaetostomus setosus, una especie previamente considerada dentro del género Dolichancistrus, carece de los caracteres diagnósticos de sus congéneres putativos y es considerada como más cercanamente relacionada con otros miembros del grupo Chaetostoma. Consecuentemente, esta especie es considerada como incertae sedis dentro del grupo Chaetostoma. Dolichancistrus es diagnosticado, y se presenta una clave para sus especies, así como diagnosis y redescripciones para todas las especies reconocidas actualmente dentro del género.

Arrhinolemur scalabrinii Ameghino, 1898, of the late Miocene: a taxonomic journey from the Mammalia to the Anostomidae (Ostariophysi: Characiformes)

The fossil species Arrhinolemur scalabrinii, which was described from late Miocene deposits of Entre Ríos, Argentina, is reevaluated. Whereas the species was originally placed in the Primates (Mammalia) and later made the unique member of the order Arrhinolemuroidea within the Mammalia, our analysis indicates that the specimen is rather a fish of the genus Leporinus, family Anostomidae (Characiformes). The species is redescribed, and the characters that support its new generic assignment are discussed.

A espécie fóssil Arrhinolemur scalabrinii, descrita de depósitos do Mioceno Superior de Entre Ríos, Argentina, é reavaliada. Apesar da espécie ter sido originalmente incluída em Primata (Mammalia), constituindo-se posteriormente no único membro da ordem Arrhinolemuroidea dentro de Mammalia, nossa análise indica que o espécime trata-se de um peixe do gênero Leporinus, família Anostomidae (Characiformes). A espécie é redescrita, e os caracteres que fundamentam a nova posição do gênero são discutidos.