Osteology and myology of the cephalic region and pectoral girdle of Erethistes pusillus, comparison with other erethistids, and comments on the synapomorphies and phylogenetic relationships of the Erethistidae (Teleostei: Siluriformes)

The cephalic and pectoral girdle structures of the erethistid Erethistes pusillus(Erethistinae) are described and compared with those of another species of the subfamily Erethistinae, namely Hara filamentosa, and of the single species of the subfamily Continae, Conta conta, as well as of several other catfishes, as the foundation for a discussion on the synapomorphies and phylogenetic position of the Erethistidae. The observations and comparisons support de Pinna's phylogenetic hypothesis, according to which the Erethistidae is the sister-group of the Aspredinidae, with the clade formed by these two families being the sister-group of the Sisoridae sensu stricto. In addition, the observations and comparisons pointed out a new, additional character to diagnose the family Erethistidae, namely: mesocoracoid arch deeply bifurcated dorsally.