Ten new species of the genus Brevisomabathynella Cho, Park and Ranga Reddy, 2006 (Malacostraca, Bathynellacea, Parabathynellidae) from Western Australia

Abstract

Ten new species of Brevisomabathynella Cho, Park and Ranga Reddy, 2006 are described and illustrated from the arid region of Western Australia. Comparison of the external morphology revealed the presence of three common characters distributed among the 10 species: the five-segmented antenna, the absence of the basipodal seta on the male thoracopod VIII and the absence of a basiventral seta on the uropodal exopod. This character combination is not found in Notobathynella and Billibathynella, but only in Brevisomabathynella, a genus known from two described species both with unusual characters. Despite the three common attributes, the 10 new species differ remarkably from these two described species, but could not be defined by their own synapomorphy. Consequently, and cognizant of a previously performed molecular analysis, we assign the 10 new species to Brevisomabathynella and amend the generic diagnosis. The species inhabit shallow aquifers in groundwater calcretes and each appears to be endemic to a given calcrete formation. The two species previously known and the 10 species now described include four sympatric species pairs, with similar-sized sympatric species differing markedly in body form. Brevisomabathynella inhabit groundwater up to at least marine salinity.