Two new catfish species from central Brazil comprising a new clade supported by molecular phylogeny and comparative osteology (Siluriformes: Trichomycteridae)

Phylogeny and historical biogeography of neotropical catfishes Trichomycterus (Siluriformes: Trichomycteridae) from eastern Brazil

The catfish subfamily Trichomycterinae is widely distributed in South America inhabiting several habitats, but specially mountain streams. Trichomycterus is the most speciose trichomycterid genus and recently due to his paraphyletic condition has been restricted to a clade from eastern Brazil called Trichomycterus sensu stricto comprising around 80 valid species distributed in seven areas of endemism of eastern Brazil. This paper aims to analyse the biogeographical events responsible for the distribution of Trichomycterus s.s., by reconstructing the ancestral data based on a time-calibrated multigene phylogeny. A multi-gene phylogeny was generated using 61 species of Trichomycterus s.s. and 30 outgroups, with divergence events calculated based on the estimated origin of Trichomycteridae. Two event-based analyses were applied to investigate the biogeographical events responsible the present distribution of Trichomycterus s.s. and suggest that the modern distribution of the group is a result of different vicariance and dispersal events. The diversification of Trichomycterus s.s. subgenera occurred in the Miocene, except for Megacambeva, with different biogeographical events shaping its distribution in eastern Brazil. An initial vicariant event split up the Fluminense ecoregion from the Northeastern Mata Atlantica + Paraíba do Sul + Fluminense + Ribeira do Iguape + Upper Paraná ecoregions. Dispersal events occurred mainly between Paraíba do Sul and neighboring river basins, with additional dispersal events from Northeastern Mata Atlantica to Paraíba do Sul, from São Francisco to Northeastern Mata Atlântica, and from Upper Paraná to São Francisco.

Perils of Underestimating Species Diversity: Revisiting Systematics of Psammocambeva Catfishes (Siluriformes: Trichomycteridae) from the Rio Paraíba do Sul Basin, South-Eastern Brazil †

Psammocambeva, a subgenus of Trichomycterus s.s., includes a clade endemic to south-eastern Brazil, the Psammocambeva alpha-clade (PAC), containing species with similar colour pattern and fin morphology, making difficult their identification without accurate examination. The greatest diversity of PAC species occurs in the Rio Paraíba do Sul basin area (RPSA), situated within the Atlantic Forest, one of the most important and endangered biodiversity centres in the world. Herein, we: perform a multigene phylogeny focusing on species of PAC; revise morphological characters diagnosing species of PAC from the RPSA, with special attention to those equivocally synonymised in a recent study; describe two new species, and provide a key for species identification. Molecular and morphological evidence supported the recognition of eight valid species belonging to four species complexes. Data indicated that T. auroguttatus, T. travassosi, and T. longibarbatus are valid species. Finally, we discuss the negative impacts of underestimating species diversity in regions under the intense process of natural habitat loss, concluding that integrative approaches are important tools to estimate species diversity, but they should include a range of morphological characters informative to delineate and diagnose groups and their respective species, in association with phylogenies generated by robust molecular datasets.

Phylogenetic relationships of a new catfish of the genus Trichomycterus (Siluriformes, Trichomycteridae) from the Brazilian Cerrado, and the role of Cenozoic events in the diversification of mountain catfishes

The Brazilian Cerrado highlands shelter the headwaters of the three largest South American hydrographic basins, where a great species diversity is concentrated, but some biological groups are still insufficiently known. The focal taxa of this study are trichomycterid catfishes of the subgenus Cryptocambeva, genus Trichomycterus, endemic to mountain areas of south-eastern Brazil. The primary objective of this study is to test through a molecular phylogeny if a new species collected in streams of the upper Rio Paraná basin draining the Serra da Canastra is sister to T. macrotrichopterus, endemic to the upper Rio São Francisco at another facet of the Serra da Canastra, as suggested by morphological data. The analysis corroborated sister group relationships between these two species, besides supporting four main clades in Cryptocambeva, each of them endemic to distinct mountain regions. A time-calibrated analysis supported the divergence timing between the new species and T. macrotrichopterus at the Pliocene, which is chronologically compatible with the final period of intense fluvial configuration re-arrangement, when São Francisco headwater streams were captured by the Paraná basin. The new species herein described is similar to T. macrotrichopterus and distinguished from all other species of Cryptocambeva by having a long pectoral-fin filament. These two species are distinguished from each other by characteristics of the latero-sensory system, colour pattern and bone morphology.

Phylogenetic position of Trichomycterus astromycterus (Siluriformes: Trichomycteridae), an enigmatic trichomycterid from eastern Brazil, inferred from molecular data

Recently in this journal, a new trichomycterine from eastern Brazil, Trichomycterus astromycterus, was described and considered possibly related to the Chilean Bullockia maldonadoi due to morphological similarities. Subsequently, osteological data supported T. astromycterus in the subgenus Psammocambeva of Trichomycterus, from eastern Brazil. Phylogenetic analyses, performed here, using a multigene data set for a broad trichomycterine sample, corroborate T. astromycterus as a member of Psammocambeva, reinforcing the importance of molecular data for inferring trichomycterine relationships but showing that osteological data alone may infer correctly phylogenetic placements when using broad comparative databases.

A new catfish of the genus Trichomycterus from the Rio Paraíba do Sul Basin, south-eastern Brazil, a supposedly migrating species (Siluriformes, Trichomycteridae)

A new species of the catfish genus Trichomycterus is described from the Rio Paraíba do Sul, south-eastern Brazil. This species exhibits some morphological character states that are unique amongst congeners, including a robust opercle and a long interopercle with numerous odontodes (50–60 opercular and 90–100 interopercular), a black bar on the basal portion of the caudal fin and a dark brown flank with a well delimited dorsal yellow stripe. It also exhibits some morphological traits that are uncommon amongst congeners, such as the presence of nine pectoral-fin rays. The presence of a shallow hyomandibular outgrowth and a ventrally expanded pre-opercular ventral flap suggests that this species is closely related to T. melanopygius, T. pradensis and T. tete. The new species also differs from T. melanopygius, T. pradensis and T. tete by having an emarginate caudal fin and a single median supra-orbital pore S6. Anecdotal evidence suggests that T. largoperculatus and T. pradensis have migratory habits, a condition not previously reported for eastern South American trichomycterines.