Sistemática de Baryancistrus Rapp Py-Daniel, 1989 (Loricariidae: Hypostominae)

Abstract

The main objectives of the present thesis were to provide a taxonomic review of the genus Baryancistrus, to assess the phylogenetic relationships within the genus, to check its monophyly and to understand the phylogenetic position of the genus within the tribe Ancistrini. The current species included in Baryancistrus were revised based on examination of type material, topotypes, specimens deposited in several fish collections and original descriptions. A phylogenetic hypothesis is proposed for the relationships of the genera of Ancistrini and for the species of Baryancistrus based on 192 characters of 110 terminal taxa. Four of the six species already proposed for the genus were accepted plus the recognition of more 10 new species. An identification key is presented for all species recognized in the genus after the taxonomic revision. Baryancistrus was restricted to the clear-water rivers of the Amazon basin that drain the Guiana and Brazilian Shields. Parsimony analyses resulted in 48 equally most parsimonious trees with 1,704 steps, consistency index of 0.16 and retention index of 0.67; strict-consensus tree was rooted in Rhinelepis strigosa. Baryancistrus were recovered as a natural group, excluding the ones from rio Orinoco basin, in Venezuela. Monophyly of Baryancistrus was supported by 12 non-exclusive synapomorphies, and the most relevant are the thick and round condyle of the quadrate for articulation with the angulo-articular, the presence of a deep depression on the posterior tip of the opercle, elongate maxillary and the presence of seven to eigth infraorbitals. The 14 species of the genus were grouped as (Baryancistrus sp. “membrana” (Baryancistrus sp. “Jari” ((Baryancistrus sp. “Trombetas” (B. longipinnis, B. niveatus)) ((Baryancistrus sp. “jolie” (Baryancistrus sp. “Tapajos”, B. xanthellus))) ((B. chrysolomus (Baryancistrus sp. “Teles Pires”, Baryancistrus sp. “Porteira”)) ((Baryancistrus sp. “bola branca” (Baryancistrus sp. “Araguaia”, Baryancistrus sp. “Culuene”))))), comprising the sister-group of the remaining Ancistrini with hypertrophied membrane posterior to the last dorsal fin ray. Relationships of the genera within Ancistrini are discussed with the proposition of revalidation of previously synonymized genera and new taxonomic arrangements.