Taxonomic novelties within Brazilian pea crab species: a new genus for Pinnixa latissima Coelho, 1997 and reallocation of Pinnixa gracilipes Coelho, 1997 (Pinnotheridae, Pinnixinae)

Abstract

Coelho (1997) described three new species of Pinnixa for the Brazilian coast, two of which have remained in the genus until now. Both species, Pinnixa gracilipes and Pinnixa latissima, have never been addressed in taxonomic studies since. Recent phylogenetic and taxonomic studies of the subfamily Pinnixinae have led to new perspectives that resulted in the description of new genera and allocation of some species of Pinnixa to other genera. Given this context, the present study reassesses the taxonomic status of P. gracilipes and P. latissima using morphological data. A new genus Brasilixa gen. nov. is formally described and named herein to accommodate P. latissima, which can be distinguished from other pinnixine genera by the relative width of the carapace, the arc-shaped cardiac ridge, the morphology of the third maxilliped and the presence of spines on the basi-ischium of pereopods 4 and 5. Pinnixa gracilipes is reallocated to Rathbunixa based on shared similarities including the well-defined carapace regions, the presence of a triangular elevation on the cardiac region, slender pereopods and similar male first gonopod morphology. A key to genera and species of Pinnixinae of Brazil is also presented.