Taxonomic revision of Sturisoma Swainson, 1838 (Loricariidae: Loricariinae), with descriptions of four new species.

A taxonomic revision of Sturisoma is presented. Individuals including both type and non-type specimens of all valid species were examined. Sturisoma was found to comprise 10 valid species: Sturisoma barbatum, Sturisoma brevirostre, Sturisoma graffini, Sturisoma guentheri, Sturisoma lyra, Sturisoma monopelte, Sturisoma nigrirostrum, Sturisoma reisi, Sturisoma rostratum, and Sturisoma tenuirostre. Furthermore, four new species are described: Sturisoma ghazziae, new species, from the Araguaia River, belonging to the Tocantins-Araguaia basin, Central Brazil; Sturisoma careirensia, new species, from the middle Amazon basin, Brazil; Sturisoma rapppydanielae, new species, from the Purus River, Amazon basin, Brazil; and Sturisoma defranciscoi, new species, from the Putumayo and Solimões rivers, upper Amazon basin, Colombia, and Brazil. Sturisoma robustum is confirmed as synonym of S. barbatum, species registered along the Paraguay/Parana/La Plata River basin in Argentina, Brazil, and Paraguay. New records were found for S. nigrirostrum as present in the upper Amazon basin, in the Yavari River, Brazil, in addition to its already known locality, the Ucayali River, Peru. The distribution of the type species of the genus S. rostratum is limited to the lower portion of the Amazon basin in the Araguaia, Maranhão, Mearim, Tapajós, and Tocantins rivers and its affluents, Brazil, in contrast to the assumed widespread distribution across the main basins of South America, as previously proposed for the species; the Mearim River is a new record for the species. Updated diagnoses and descriptions are offered for species of Sturisoma, in addition to distribution maps and an identification key for the species.

A new species of Sturisoma Swainson, 1838 (Loricariidae: Loricariinae), from the Madeira River basin, with a discussion of historical biogeography of western Amazonas and Paraguay River basins.

A new loricariin species of Sturisoma is described from the Cautário, Guaporé, Mamoré, Machado and Soteiro rivers, Madeira River basin, in Bolivia and Brazil. The new species is distinguished from its congeners by the presence of a middorsal longitudinal, thin dark brown stripe on the caudal peduncle, extending from two or three plates posterior to the dorsal-fin base, reaching the origin of the caudal fin, or one or two plates anterior to the origin of the caudal fin; small squarish anteriormost abdominal plates; and a middorsal longitudinal dark-brown stripe from first predorsal plate to near the dorsal-fin origin. Furthermore, the new species is diagnosed from congeners by plate morphology, counts on the median series, coalescent plates and ventrolateral thoracic plates, in addition to measurements related to body and head structures. An analysis of genetic distances using cytochrome C oxidase subunit 1 gene marker of the mitochondrial genome between the new species and several congeners is presented, in addition to a likelihood analysis to illustrate the position of the new taxon within Sturisoma. An identification key for species of the genus currently recorded at the upper Amazonas River basin is provided.

A new species of Ancistrus (Siluriformes: Loricariidae) from Tapajós and Xingu basins, Brazil

A new Ancistrus species is described from Tapajós and Xingu river basins. It is distinguished from its congeners by the singular body color pattern, consisting of dark vermiculated stripes almost all over the body, and also by combination of features as a narrow head, large internostril distance, and absence of rows of enlarged odontodes on the lateral plates. In addition, the new species is distinguished from congeners that inhabit the rio Tapajós basin by the presence of a fully-developed adipose fin (vs. adipose fin absent in Ancistrus parecis and A. tombador, and vestigial adipose fin or absent in A. krenakarore). It differs from A. ranunculus, also from the rio Xingu, by the color pattern, smaller body size, smaller gill opening, and narrower cleithral width. The new taxon adds a new record to the list of species shared among the Xingu and Tapajós basins.(AU)

Uma nova espécie de Ancistrus é descrita das bacias dos rios Tapajós e Xingu. Distingue-se de suas congêneres pelo padrão de colorido único, que consiste em listras vermiculadas escuras em quase todo o corpo, e também pela combinação de características como cabeça estreita, maior distância entre as narinas e ausência de séries de grandes odontódeos nas placas laterais. Adicionalmente, a nova espécie pode ser diferenciada de suas congêneres da bacia do rio Tapajós pela presença de uma nadadeira adiposa totalmente desenvolvida (vs. nadadeira adiposa ausente em Ancistrus parecis e A. tombador, nadadeira adiposa vestigial ou ausente em A. krenakarore). Ela difere de A. ranunculus, a única outra espécie do rio Xingu, pelo padrão de colorido, menor tamanho corporal, menor abertura branquial e menor largura entre os cleitros. O novo táxon adiciona um novo registro à lista de espécies compartilhadas entre as bacias do Xingu e Tapajós.(AU)

Corydoras fulleri (Siluriformes: Callichthyidae), a new catfish species from the rio Madeira basin, Peru.

A new long-snouted Corydoras species is described from two tributaries of the río Manuripe and a tributary of the río Madre de Dios, rio Madeira basin, Peru. Corydoras fulleri can be distinguished from its congeners by having the following features: (a) branch of the temporal sensory canal at sphenotic, which gives rise to the supraorbital canal, with two pores; (b) upper tooth plate of branchial arch with three series of teeth; (c) area at the corner of the mouth, ventral to the maxillary barbel, with a small fleshy flap; (d) two moderate-sized dark-brown or black blotches on caudal-fin base, one on its lateral portion and another one on its dorsal portion, blotches variably diffuse and/or fused with each other; (e) absence of a dark-brown or black stripe transversally crossing the orbit; (f) a longitudinal dark-brown or black stripe on the postdorsal region of flank midline, variably fused with the lateral peduncular blotch, some specimens with slender, longitudinally elongated, dark-brown or black blotch on flank midline, forming a dash-like marking, stripe or dash-like blotch diffuse in some specimens; and (g) region around dorsal-fin origin generally lacking dark brown or black blotch, or displaying diffuse blotch.

Review of the genus Malacoctenus (Actinopterygii: Labrisomidae) from the Southwestern Atlantic, with description of two new species.

The labrisomid genus Malacoctenus from Southwestern Atlantic is reviewed. Two new species of scaly blennies formerly reported by several authors as Malacoctenus triangulatus are described. One is found at the oceanic islands Fernando de Noronha Archipelago and Atol das Rocas, and the other is distributed along the Brazilian coastline. The two new species differ from other species of the genus and from each other by different combinations of the number of lateral-line scales, number and size of head cirri, and color pattern. Molecular data also support species' distinctiveness between M. triangulatus and the species described herein. Two additional recognized Brazilian species, M. delalandii and M. brunoi are described and illustrated and an identification key to all recognized Atlantic species is provided.

Iterative taxonomy reveals a new species of Trichomycterus Valenciennes 1832 (Siluriformes, Trichomycteridae) widespread in Rio Doce basin: a pseudocryptic of T. immaculatus.

This paper reports on a new species of Trichomycterus from the Rio Doce basin. Unusually for new taxa in the genus during the past few decades, the new species is not narrowly endemic but instead widely distributed in its major drainage, the Rio Doce. The species has been collected and deposited in scientific collections for some years, but has been systematically misidentified as the more abundant Trichomycterus immaculatus or, to a lesser degree, as other morphologically similar species from south-eastern Brazil such as T. nigricans and T. pradensis. A combination of several morphological characteristics, such as vertebral number, pectoral-fin ray counts, pigmentation pattern and barcoding distance, were iteratively used and unambiguously distinguish the new species from all congeners. The present case reveals a pattern of diversity-discovery in which rare and narrowly endemic morphologically conspicuous species are discovered and described before visually inconspicuous taxa, even when the latter are more abundant and widespread. The morphological similarities among south-eastern Brazilian species with a uniform dark-grey color serve as basis for a brief discussion about the concepts of cryptic and pseudo-cryptic species in Trichomycterus and their consequences for potentially hidden diversity in the genus.

A journey through the Amazon Middle Earth reveals Aspidoras azaghal (Siluriformes: Callichthyidae), a new species of armoured catfish from the rio Xingu basin, Brazil.

Aspidoras azaghal n. sp. was discovered during a multitaxonomic scientific expedition to the remote Amazon Terra do Meio region in tributaries to the rio Xingu basin, Pará, Brazil. The new species can be promptly distinguished from its congeners by the following combination of features: (a) absence of the first dorsal-fin element; (b) parieto-supraoccipital fontanel located medially on bone; (c) absence of a longitudinal dark-brown or black stripe along flank midline; (d) ventral surface of trunk covered by clearly smaller, irregular and/or roundish platelets; (e) inner laminar expansion of infraorbital 1 well developed; (f) relatively wide frontal bone, with width equal to half of entire length; (g) absence of a thick, longitudinal conspicuous dark-brown stripe along dorsal portion of flank; and (h) poorly developed serrations on posterior margin of the pectoral-fin spine. Besides morphological evidence, the molecular analyses indicated significant differences between the new species and its congeners, with A. albater and A. raimundi as its closest species, showing 6.53% of genetic differentiation in both cases. The intraspecific molecular data revealed gene flow (peer fixation index, FST = 0.05249, P > 0.05, for the cytochrome oxidase I (COI) marker and FST = -0.01466, P > 0.05, for the control region) between specimens upstream and downstream from a 30-m height waterfall at the type-locality, which therefore represent a single population. Furthermore, it was possible to observe a unidirectional gene flow pattern, with genetic diversity increasing in the downstream direction.

A new Corydoras (Ostariophysi: Siluriformes: Callichthyidae) with an unusual sexual dimorphism from the rio Juruena basin, Brazil.

A new Corydoras is described from the rio Juruena system, upper rio Tapajós drainage, Amazon basin, Brazil. The new Corydoras is distinguished from all congeners by presenting a combination of a conspicuous broad vertical dark bar on head, at the level of the eye (mask), an overall light background color without large blotches or stripes on body or fins, the presence of two to four small dark blotches along the midline, and pectoral spine with antrorse serrations on its posterior margin. Males of the new species possess numerous, well-developed odontodes over the lateral portions of head, pectoral girdle, and pectoral spines, an uncommon feature for the genus. The new species is hypothesized to belong, within the genus Corydoras, either to Lineage 6 or Lineage 9.

Deconstructing an octogenarian misconception reveals the true Corydoras arcuatus Elwin 1938 (Siluriformes: Callichthyidae) and a new Corydoras species from the Amazon basin.

After 80 years of misidentifications, the analysis of the holotype of Corydoras arcuatus plus several non-type specimens attributed to this species allowed its recognition and also revealed a new species, both sharing the following diagnostic features: a long, arched, continuous black stripe that runs parallel to the dorsal profile of the body and extends at least from the anterior margin of the first dorsolateral body plate to the posterior portion of caudal peduncle; absence of transverse black bars on caudal fin; infraorbital 2 in contact with sphenotic and compound pterotic. In addition to these features, C. arcuatus can be distinguished from congeners by having the posterior margin of both dorsal and pectoral spines with laminar serrations directed towards their origins. The new species can be additionally distinguished from its congeners by presenting the following combination of features: ventral surface of trunk entirely or partially covered by relatively large and coalescent platelets; absence of spots or blotches on dorsal fin; and posterior margin of both dorsal and pectoral spines with serrations directed towards their tips. Finally, an identification key to all arc-striped species of Corydoras is provided.

Poor taxonomic sampling undermines nomenclatural stability: A reply to Roxo et al. (2019).

A recent study based on genomic data by Roxo et al. (2019) provided a phylogeny of the Loricariidae, the largest catfish family and second largest Neotropical fish family with approximately 1,000 species. The study represents a valuable and innovative contribution for understanding higher-level relationships within the family. The phylogenetic tree inferred by Roxo et al. (2019) thoroughly corroborates the monophyly and relationships of most currently accepted subfamilies of Loricariidae, based on a fair taxon sampling (nearly 14% of the species in the family) representing most genera of each but one of the subfamilies, the Lithogeninae, the sister-group of the remaining members of the family (Pereira & Reis, 2017; Reis et al., 2017). In addition to a hypothesis of relationships, Roxo et al. (2019) also proposed a series of lower-level taxonomic changes, which are deemed premature considering that the taxonomic sampling of the study targeted higher-level clades, and go against one of the pillars of biological classification: nomenclatural stability (e.g., Heterick & Majer, 2018; Beninger & Backeljau, 2019). Here we (1) discuss implications of inadequate taxonomic sampling as a basis for changes in classification of species; (2) explain why the taxonomic sampling design of Roxo et al. (2019) is inadequate for the proposed nomenclatural changes; and (3) advocate that changes to classifications must be grounded on phylogenies with dense sampling of taxa at the relevant level.

Comparative gross encephalon morphology in Callichthyidae (Teleostei: Ostariophysi: Siluriformes)

Callichthyidae comprises the subfamilies Callichthyinae and Corydoradinae, both of which are morphologically distinct and monophyletic. Although there is consensus regarding the monophyly of the family, the relationships of about 80% of its species, currently included in the genus Corydoras, remain poorly known. Despite the vast amount of osteological information for Teleostei, knowledge regarding the phylogenetic implications of encephalon anatomy is sparse and represents a poorly explored source of potential characters. The present study aims to describe the encephalon morphology in members of the Callichthyidae in order to propose new characters that may help address phylogenetic questions regarding this group. In addition to representatives of Callichthyidae, specimens belonging to the Nematogenyidae, Trichomycteridae, Scoloplacidae, Astroblepidae and Loricariidae were dissected for comparative purposes. Head dissection revealed information on the structure of the medulla spinalis, rhombencephalon, mesencephalon, diencephalon and telencephalon. The conditions observed on the encephalons examined suggest that representatives of Callichthyidae have great taste perception and processing, while Corydoradinae stand out for visual acuity and Callichthyinae for mechanoreception processing subunits. Our results also indicate that the encephalon has important features for systematic studies of the family bringing greater resolution to current phylogenetic hypotheses.(AU)

Callichthyidae é composto por Callichthyinae e Corydoradinae, ambos morfologicamente distintos e monofiléticos. Apesar do consenso em relação ao mofiletismo da família, as relações de cerca de 80% de suas espécies, atualmente incluídas no gênero Corydoras, permanecem pouco conhecidas. Apesar da grande quantidade de informação osteológica sobre Teleostei, o conhecimento sobre as implicações filogenéticas da anatomia do encéfalo é escasso e, por isso, considerado uma fonte inexplorada de caracteres. O objetivo do presente estudo é a descrição morfológica dos encéfalos de Callichthyidae, fornecendo novos caracteres que podem elucidar questões filogenéticas para o grupo. Além dos representantes de Callichthyidae, espécimes pertencentes a Nematogenyidae, Trichomycteridae, Scoloplacidae, Astroblepidae e Loricariidae foram dissecados para fins comparativos. A dissecção do crânio revelou informações sobre a estrutura da medulla spinalis, rhombencephalon, mesencephalon, diencephalon e telencephalon. As condições observadas nos encéfalos sugerem que representantes de Callichthyidae possuem grande capacidade de percepção e processamento químico, enquanto os Corydoradinae se destacam pela acuidade visual e os Callichthyinae pelas unidades de processamento mecanoreceptoras. Nossos resultados indicam que os encéfalos detêm características importantes para contribuir com estudos sobre a sistemática da família, trazendo maior resolução para as hipóteses atuais de reconstrução filogenética.(AU)

A new species of Aspidoras (Siluriformes: Callichthyidae) from a small coastal drainage in northeastern Brazil

A new species of Aspidoras from the rio da Dona basin, a small coastal river drainage in Bahia State, is described herein. The new taxon differs from its congeners by presenting infraorbital 1 with well-developed ventral laminar expansion, nuchal plate nearly reaching to or sometimes contacting posterior process of parieto-supraoccipital, anterior tip of nuchal plate just posterior to dorsal margin of first dorsolateral body plate, and blotches on dorsal half of dorsolateral body plates and/or ventral half of ventrolateral body plates fused with midlateral series of blotches, forming three or four enlarged and oblique black blotches.(AU)

Uma nova espécie de Aspidoras da bacia do rio da Dona, uma pequena drenagem costeira do estado da Bahia, é aqui descrita. O novo táxon difere de suas congêneres por apresentar infraorbital 1 com expansão laminar ventral bem desenvolvida, placa nucal quase alcançando ou alcançando o processo posterior do parieto-supraoccipital, extremidade anterior da placa nucal apenas posterior à extremidade dorsal da primeira placa dorsolateral, e três ou quatro manchas pretas grandes na porção lateral mediana do corpo, geralmente inclinadas anterodorsalmente e conectadas à série de manchas dorsais e fusionadas à série ventral de manchas.(AU)

Wrapped in flames: Corydoras hephaestus, a new remarkably colored species from the Rio Madeira basin (Teleostei: Callichthyidae).

A new species of Corydoras is described from the upper Rio Machado, Rio Madeira basin, Rondônia State, Brazil. The new species can be distinguished from its congeners by the absence of contact between the posterior process of the parieto-supraoccipital and the nuchal plate; a ventral laminar expansion of the infraorbital 1 conspicuously developed; and the posterior margin of the pectoral-fin spine with serrations along almost of its entire length, only lacking in the distal portion. Additionally, Corydoras hephaestus possesses dorsal and pectoral spines short, and exhibits an unusual color pattern in life. The conservation status of the new species and other endemic species are briefly commented.

New species of Scleromystax Günther, 1864 (Siluriformes: Callichthyidae) - extending the meridional distribution of genera endemic to the Atlantic Forest

The genus Scleromystax includes species occurring in several coastal river basins from southern Bahia to southern Santa Catarina States. Examination of Scleromystax specimens sampled from the laguna dos Patos drainage revealed a new taxon, further extending the distribution of the genus to the southern border of the Atlantic forest. The new species differs from its congeners by the second infraorbital ventrally expanded. It is also distinct, except from S. macropterus and S. salmacis , by roughly oblique, elongate, dark brown blotches along body; large specimens displaying cranial fontanel completely occluded, leaving just a shallow fossae; and sexually dimorphic features inconspicuous, i.e. preopercular (cheek) region similar in males and females, and dorsal and pectoral fins of males slightly longer than in females. Herein, we also extend the record of Scleromystax salmacis to the rio Tramandaí drainage.(AU)

O gênero Scleromystax inclui espécies distribuídas nas diversas bacias hidrográficas costeiras entre o sul do Estado da Bahia e o sul do Estado de Santa Catarina. O exame de exemplares de Scleromystax coletados nos sistema da laguna dos Patos revelou um novo táxon, estendendo a distribuição do gênero para o limite austral da Mata Atlântica. A nova espécie difere de seus congêneres pelo segundo infraorbital expandido ventralmente. Também se distingue, exceto de S. macropterus e S. salmacis , por manchas castanho-escuras alongadas e oblíquas ao longo do corpo; espécimes grandes apresentando a fontanela craniana completamente oclusa, restando somente uma depressão superficial; e características de dimorfismo sexual inconspícuas, i.e. região pré-opercular semelhante em machos e fêmeas, e nadadeiras dorsal e peitoral dos machos sutilmente mais longa que das fêmeas. No presente estudo, o registro de S. salmacis é estendido até a drenagem do rio Tramandaí.(AU)

A new species of Aspidoras Ihering (Siluriformes: Callichthyidae: Corydoradinae) from the Rio Xingu Basin, Pará, Brazil.

A new species of Aspidoras is described from an unnamed stream in the Rio Xingu Basin, Castelo de Sonhos municipality, Pará State, representing the northernmost record of the genus along the edge of the Brazilian Shield in the Amazon Basin. Aspidoras marianae is easily distinguished from all congeners in having minute odontode-bearing platelets scattered over the surface of the snout region, minute platelets between the parieto-supraoccipital process and the nuchal plate, and other shared features related to color pattern, morphometrics, meristics and morphological data. Comments about exclusive and shared features are presented.

A new species of Corydoras Lacépède, 1803 (Siluriformes: Callichthyidae) from the upper rio Paraná basin, Brazil

A new species of Corydoras is described from three tributaries of the rio Ivaí drainage, upper rio Paraná basin, Paraná State, Brazil. The new species can be distinguished from most of its congeners by the presence of three nasal pores. Other diagnostic features are the lower number of serrations in posterior margin of pectoral and dorsal spines and presence of four to six small black blotches along the midline of the flank. The possible mimetic relationship between the new species and Characidium heirmostigmata is discussed. Uma espécie nova de Corydoras é descrita de três tributários da drenagem do rio Ivaí, bacia do alto rio Paraná, estado do Paraná, Brasil. A espécie nova se diferencia da maioria de suas congêneres por apresentar três poros nasais. Outras características diagnósticas são o menor número de serrilhas na margem posterior dos espinhos peitoral e dorsal e presença de quatro a seis manchas pretas pequenas ao longo da linha mediana do flanco. A possível relação mimética entre a espécie nova e Characidium heirmostigmata é discutida.

A new long-finned Corydoras Lacépède, 1803 (Siluriformes: Callichthyidae) from the lower rio Paraná basin, Brazil

A new species of Corydoras is described from the lower rio Paraná basin, just downstream from Itaipu Dam, Brazil, close to Paraguay boundary. The new species can be distinguished from most of its congeners by the infraorbital 2 with a posterior laminar expansion conspicuously reduced, first and second dorsal-fin branched rays conspicuously elongated in males, mesethmoid entirely covered by skin, and by the presence of four to six irregular black or brownish blotches on the midline of the flank. The probable occurrence of the new species in the floodplain of the upper portion of the rio Paraná drainage is discussed. Uma espécie nova de Corydoras é descrita da bacia do baixo rio Paraná, logo a jusante da barragem de Itaipu, Brasil, próximo a fronteira com o Paraguai. A espécie nova pode ser distinguida da maioria de suas congêneres pelo infraorbital 2 com uma expansão laminar posterior conspicuamente reduzida, primeiro e segundo raios ramificados da nadadeira dorsal conspicuamente alongados nos machos, mesetmoide totalmente coberto por pele e presença de quatro a seis manchas pretas ou amarronzadas irregulares na linha mediana do flanco. Discute-se a provável ocorrência da espécie nova na planície de inundação da bacia da porção superior do rio Paraná.

A new Corydoras Lacépède, 1803 (Siluriformes: Callichthyidae) from the rio São Francisco basin, Brazil

A new species of Corydoras is described from the rio São Francisco basin in northeastern Brazil, Minas Gerais and Bahia States. The new species is distinguished from most of its congeners by the anterior portion of the infraorbital 1 very large, conspicuously expanded towards the anteroventral margin of the snout and almost entirely covering its lateral margin. Other characters that distinguish the new species are the infraorbital 2 slender on its dorsal tip, contacting only sphenotic and not compound pterotic; and the presence of two laterosensory canals on trunk. A phylogenetic analysis including the new species found it sister-group of C. flaveolus, and both species sister-group of C. paleatus. An identification key to the species of the rio São Francisco basin is also provided.

Uma espécie nova de Corydoras é descrita da bacia do rio São Francisco no nordeste do Brasil, estados de Minas Gerais e Bahia. A espécie nova se distingue da maioria de suas congêneres por apresentar a porção anterior do infraorbital 1 muito desenvolvida, expandindo-se conspicuamente em direção à margem anteroventral do focinho, quase cobrindo completamente sua margem lateral. Outros caracteres que distinguem a espécie nova são o infraorbital 2 estreito em sua extremidade dorsal, em contato apenas com o esfenótico e não com o pterótico composto, e presença de somente dois canais látero-sensoriais no tronco. Uma análise filogenética incluindo a espécie nova encontrou-a como grupo-irmão de C. flaveolus, e ambas como grupo-irmão de C. paleatus. Uma chave para identificação das espécies da bacia do rio São Francisco também é fornecida.

A new species of Xyliphius, a rarely sampled banjo catfish (Siluriformes: Aspredinidae) from the rio Tocantins-Araguaia system

Xyliphius anachoretes, a new species of aspredinid catfish is described from the Tocantins-Araguaia River system. Xyliphius anachoretes is diagnosed by the presence of six developed retrorse serrae on posterior border of pectoral-fin spine, presence of papillae on the lower lip bearing minute branches, and only two dorsal procurrent rays. Comments about the informativeness of character-state variation among Xyliphius species and aspredinid related genera are furnished. Also, a brief discussion about conservation status of the new taxon is made.

Xyliphius anachoretes, uma nova espécie de bagre aspredinídeo é descrita para o sistema Tocantins-Araguaia. Xyliphius anachoretes é diagnosticado pela presença de seis serras retrorsas desenvolvidas na borda posterior do espinho da nadadeira peitoral, presença de papilas no lábio inferior apresentando minúsculas ramificações, e somente dois raios pró-correntes dorsais. Comentários sobre a informação contida na variação de estados de caráter entre as espécies de Xyliphius são fornecidos. Além disso, uma breve discussão sobre o estado de conservação do novo táxon é feita.

Corydoras ortegai, a new species of corydoradine catfish from the lower río Putumayo in Peru (Ostariophysi: Siluriformes: Callichthyidae)

A new species of Corydoras, C. ortegai, is described from tributaries of the lower course of río Putumayo in Peru, close to the border with Brazil and Colombia. The new species seems to be related to Corydoras reynoldsi, C. weitzmani, C. panda, and C. tukano, all of which share a pattern composed of uniform light ground color on body, dark bar ("mask") across orbit, and one or two large rounded blotches midlaterally on trunk. Corydoras ortegai is easily distinguished from these species, except C. panda, mainly by the absence of a midlateral trunk blotch at the dorsal-fin level, and the rounded shape of the midlateral trunk blotch at the adipose-fin level. Corydoras ortegai differs from C. panda by its greater number of lateral body plates, lack of dorsal-fin blotch, scattered chromatophores surrounding midregion of cleithrum, caudal fin with series of small blotches restricted to rays, slenderer body, and narrower intercleithral area. Corydoras ortegai belongs to a putatively monophyletic assemblage of Corydoras that occurs mainly in the Western Amazon basin, C. tukano excepted. The occurrence of Corydoras tukano in the rio Tiquié (upper Negro basin) and its putative sister species, C. ortegai, in the western Amazon, together with similar distribution patterns shared by other groups of fishes, suggest a biogeographic relationship between these areas

Uma nova espécie de Corydoras, C. ortegai, é descrita de afluentes do baixo curso do río Putumayo no Peru, próximo a fronteira com o Brasil e Colômbia. A nova espécie parece estar relacionada a Corydoras reynoldsi, C. weitzmani, C. panda e C. tukano, as quais compartilham um padrão de colorido claro e uniforme no corpo, uma faixa escura ("máscara") através da órbita, e uma ou duas manchas grandes e arredondadas no corpo. Corydoras ortegai é facilmente distinta destas espécies, exceto C. panda, principalmente pela ausência de uma mancha lateral no corpo na altura da nadadeira dorsal, e a forma arredondada de uma mancha lateral na altura da nadadeira adiposa. Corydoras ortegai difere de C. panda pelo maior número de placas laterais no corpo, ausência de uma mancha dorsal, cromatóforos espalhados ao redor da região mediana do cleitro, nadadeira caudal com séries de pequenas manchas restritas aos raios, corpo mais delgado, e ßrea entre os cleitros mais estreita. Corydoras ortegai é assinalada a um possível grupamento monofilético de Corydoras que ocorrem principalmente na bacia amazônica ocidental, exceto C. tukano. A ocorrência de Corydoras tukano no rio Tiquié (alto curso da bacia do rio Negro) e sua possível espécie irmã, C. ortegai, na Amazônia ocidental, associada a um padrão de distribuição semelhante compartilhado por outros grupos de peixes, sugerem uma relação biogeográfica entre estas áreas