Listrura picinguabae, new species, is described from small tributary streams of rio da Fazenda, an isolated coastal river in Picinguaba, São Paulo State, southeastern Brazil. It is distinguished from all other trichomycterids, except L. nematopteryx, in possessing a single long pectoral-fin ray. It differs from L. nematopteryx by a combination of features including relative position of anal and dorsal-fin origins, higher number of anal-fin rays and opercular and interopercular odontodes, and morphology of the urohyal.

Listrura costai, new species, is described from small streams in a swampy coastal plain in the rio Jurumirim basin, Angra dos Reis Municipality, Rio de Janeiro State, southeastern Brazil. The new species is morphologically very similar to L. nematopteryx and L. picinguabae, all possessing only one long pectoral-fin ray. It differs from its congeners by possessing an autapomorphic character: first hypobranchial with an anterior process (vs. process absent). Other features such as coloration, numbers of opercular and interopercular odontodes, number of anal-fin rays, head length, and shape of some bone structures help to distinguish the new species from L. nematopteryx and L. picinguabae. Molecular analyses using partial sequences of the mitochondrial DNA genes cytochrome oxidase c subunit 1 and cytochrome b from the new species and morphologically similar species are provided. The results about both molecular markers corroborate the validity of the new species by significant genetic distance values between it and congeneric species, and by its phylogenetic position in the hypotheses performed by maximum-parsimony method.Listrura costai, espécie nova, é descrita de exemplares obtidos em pequenos córregos restritos à bacia do rio Jurumirim, município de Angra dos Reis, estado do Rio de Janeiro, sudeste do Brasil. A espécie nova é morfologicamente muito similar a L. nematopteryx e L. picinguabae, todas possuindo um único e longo raio na nadadeira peitoral. Difere-se dos seus congêneres por possuir um caráter autapomórfico: primeiro hipobranquial com um processo anterior (vs. processo ausente). Outras características como coloração, número de odontóides operculares e interoperculares, número de raios na nadadeira anal, e forma de algumas estruturas ósseas ajudam a diferenciar a nova espécie de L. nematopteryx e L. picinguabae. Análises moleculares usando sequências parciais dos genes mitocondriais citocromo oxidase c subunidade 1 e citocromo b da nova espécie e espécies morfologicamente similares são apresentadas. Os resultados de ambos os marcadores moleculares corroboram a validade da espécie nova pelos valores significativos das distâncias genéticas entre esta e as espécies congenéricas, e por sua posição filogenética nas hipóteses feitas pelo o método de máxima parcimônia.

No abstract

The genus Listrura, Glanapteryginae, currently comprises six valid species of small and elongated trichomycterid catfishes that inhabit coastal plains of Southern and Southeastern Brazil. As primarily fossorial dwellers, species of the genus display unusual morphological adaptations and restricted habitats, which make these fishes particularly susceptible to environmental disturbance. Listrura camposi is poorly known and ranked as a Critically Endangered catfish species, according to current Brazilian list of threatened species. Description of the species was based on a single specimen collected in 1940, and for seven decades no additional specimens were reported. As a consequence, basic information about the species is unavailable. Recently, a population of L. camposi was found inhabiting a small stream tributary to rio Ribeira de Iguape basin, São Paulo State, relatively close to the type locality. On the basis of newly collected material, the species is redescribed and the first data on its habitat and ecology are presented. Conservation status is also discussed.O gênero Listrura, Glanapteryginae, compreende atualmente seis espécies válidas de bagres pequenos e alongados que habitam as baixadas costeiras do Sul e Sudeste do Brasil. Principalmente de hábitos fossoriais, as espécies do gênero apresentam adaptações morfológicas incomuns e habitat restrito, o que torna estes peixes particularmente suscetíveis a distúrbios ambientais. Listrura camposi é pouco conhecida e considerada uma espécie Criticamente em Perigo, segundo as mais recentes listas brasileiras de espécies ameaçadas. A descrição da espécie foi baseada em um único exemplar coletado em 1940 e por sete décadas nenhum espécime adicional foi relatado. Como consequência, informações básicas sobre a espécie estão indisponíveis. Recentemente, uma população de L. camposi foi encontrada habitando um pequeno córrego tributário da bacia rio Ribeira de Iguape, estado de São Paulo, relativamente próximo da localidade-tipo. Com base no material coletado recentemente, a espécie é redescrita e os primeiros dados sobre seu habitat e ecologia são apresentados. O estado de conservação também é discutido.

A new species of the armoured catfish genus Corydoras is described from the Xingu-Tapajos ecoregion, Brazilian Amazon. The new species can be distinguished from its congeners by having the following combination of features: short mesethmoid, with anterior tip poorly developed, smaller than 50% of bone length; posterior margin of pectoral spine with serrations directed towards spine tip or perpendicularly oriented; infraorbital 2 only in contact with sphenotic; ventral laminar expansion of infraorbital 1 poorly or moderately developed; flank midline covered by small dark brown or black saddles with similar size to remaining markings on body; relatively larger, scarcer and more sparsely distributed dark brown or black spots on body; absence of stripe on flank midline; caudal fin with conspicuous dark brown or black spots along its entire surface; slender body; and strongly narrow frontals. A more comprehensive description of poorly-explored internal character sources, such as the gross morphology of the brain, Weberian apparatus and swimbladder capsule elements is presented.

The trichomycterid catfish Listrura menezesi, new species, is described from a flooded area adjacent to Rio das Panelas, Rio São João basin, Cachoeiras de Macacu municipality, Rio de Janeiro State, Brazil. It represents a most valuable remnant of Atlantic Forest biome that still resists the devastation of Brazilian coastlands. Listrura menezesi can be distinguished from its congeners, except L. boticario and L. depinnai, by the absence of a dorsal fin. It mainly differs from L. boticario and L. depinnai by a continuous midlateral dark stripe along the entire body (vs. discontinuous) and a longitudinal row of irregular dots along the dorsal limit of the abdomen extending for nearly the entire body (vs. only on the posterior half of the body in L. boticario and not forming a distinct row in L. depinnai). Although the new species shares with L. boticario and L. depinnai the absence of dorsal fin, recent phylogenetic analyses show a close relationship between L. menezesi and L. macaensis, the latter having a dorsal fin. A putative apomorphic condition for this clade is presented: the abrupt widening on the mesethmoid axis starting posteriorly on the horizontal through the middle region of the autopalatine (vs. anteriorly, on the horizontal through the anterior region of the autopalatine). Listrura menezesi comes as an addition to the ichthyofauna of the Rio São João drainage, a region extensively sampled for the past 20 years and supposedly well known. This paper also highlights the vulnerability of this species and the possibility of its disappearance in the near future.