Systematics of neoplecostomus Eigenmann & Eigenmann, 1888 (Siluriformes: Loricariidae: Neoplecostominae)

Neoplecostomus currently includes sixteen valid species, with nine of those described in the last nine years. The genus is distributed at Paraná, Doce, São Francisco, Paraíba do Sul, Ribeira de Iguape, Iguaçu river basins, and other coastal and independent basins in southern and southeastern of Brazil. Moreover, there are evidences of new species for most of these basins and others basins where the genus has not been registered yet. According to the phylogenetic relationships proposed for Neoplecostominae sensu Pereira (2008) and based on morphological data, Neoplecostomus is monophyletic, contrary to the hypothesis based on molecular data, which indicates a non-monophyletic Neoplecostomus. In this context, the aims of the present study were: (1) to perform a phylogenetic analysis and a taxonomic revision of Neoplecostomus genus; (2) to evaluate the specific composition and the monophyly of the genus; and (3) to evaluate the phylogenetic relationship within the genus and among the genus and other Neoplecostominae genera. Phylogenetic analysis was performed with 273 characters from 62 terminal taxa, including species from Astroblepidae, Delturinae, Loricariinae, Hypostominae, Hypoptopomatinae and Neoplecostominae. The analysis produced only one more parsimonious tree that corroborated Neoplecostominae monophyly. Neoplecostominae is composed only by ((Pareiorhina hyptiorhachis + (Pareiorhina carrancas + (Pareiorhina pelicicei + (Pareiorhina rosai + Pareiorhina brachyrhyncha)))) + (Pareiorhina rudolphi + (Pareiorhaphis + (Isbrueckerichthys + Neoplecostomus)))))). Supported by 34 synapomorphies, Neoplecostomus was also monophyletic in our analysis. The genus showed seven exclusive synapomorphies: a (1) ventral dense plate shield surpassing the transverse line that passes through the base of the pelvic-fin insertions; (2) absence of smaller platelets between a dense plate shield and pectoral-fin insertions; (3) pectoral-fin spine distinctly curved and forming a wide and conspicuous arch; (4) distal portion of the lateropterygium distinctly spatulate; (5) conspicuous rows of enlarged and transversally flattened papillae just posterior to the dentary teeth; (6) two conspicuous rows of enlarged and transversally flattened papillae just posterior to the dentary teeth and (7) conspicuous rows of enlarged and transversally flattened papillae just posterior to the dentary teeth, with rounded format. Additionally, the intra-relationships among Neoplecostomus species were: N. bandeirante + (((N. langeanii + N. jaguari) + ((N. corumba + N. paranensis) + (N. botucatu + (N. yapo + N. selenae)))) + ((N. sp. n. Iguaçu + N. sp. n. Delfim) + (N. sp. n. Piquiri + (N. doceensis + (N. sp. n. Doce + (N. sp. n. São Francisco + N. sp. n. Araguari))))) + (N. ribeirensis + (N. sp. n. Itapemirim + ((N. franciscoensis + N. espiritosantensis) + (N. microps + (N. paraty + N. granosus)))))). As a result of the taxonomic revision, we presented a redescription of the genus and of fifteen of the sixteen valid species, with emphasis on the rediscovery of Neoplecostomus granosus and the possible type locality, one species that for several years has been identified as a synonymous of N. microps. Furthermore, seven new species were proposed for the genus and Neoplecostomus variipictus was synonimized with N. microps. (AU)