Diversity and systematics of Trichomycterus Valenciennes 1832 (Siluriformes: Trichomycteridae) in the Rio Doce Basin: iterating DNA, phylogeny and classical taxonomy

The catfish genus Trichomycterus is a recognized taxonomic bottleneck in Neotropical ichthyology. The hitherto poorly-known diversity of Trichomycterus in the Rio Doce Basin, Brazil, is here investigated using an iterative approach based on morphology and cytochrome oxidase subunit I (COI) sequence data. Specimens from the entire Rio Doce Drainage and adjacent basins are analysed, including from type localities. Iteration of different sources of data, dense sampling and taxonomic representation, plus information on relevant type specimens allows a clear view of the diversity, relationships and nomenclature of Trichomycterus in the Rio Doce Basin. Results indicate the presence of at least 14 species in the basin, seven of which are new. A lectotype is designated for Trichomycterus immaculatus and the type locality is accordingly restricted to the Rio Sao Mateus, a satellite basin north of the Rio Doce. Geographic distributions are mapped for all recognized species. The wide distributions of some species (e.g. Trichomycterus alternatus, T. immaculatus) are explained against information on geomorphological processes and comparative information on their biology. A Bayesian phylogenetic analysis shows that a large portion of the assemblage of Trichomycterus in the Rio Doce forms a clade, a pattern relevant to understanding the evolution of the genus in eastern South America.