The Australian species of Mesochra (Crustacea : Harpacticoida), with a comprehensive key to the genus

Abstract

Mesochra baylyi, sp. nov., is described, M. parva Thomson is redescribed, and M. pygmaea is partially redescribed; the variety meridionalis Steuer is shown to be in fact the normal form of the cosmopolitan M. pygmaea, of which the figures by Sars are strongly suspected of being inaccurate. A specimen from Victoria, referred by Sars to M. pygmaea, is probably but not certainly M. timsae; it is not identical with any of the above three species, which are all those so far known from Australia.

Revisionary notes are given on various other species of Mesochra; a group of species centred on the Mediterranean appear to warrant further revision, outside the scope of this paper. Finally, the keys to both sexes given by Lang (1948) are expanded and modified to include all species known to the present day.