On the land crabs of the genus Discoplax A. Milne Edwards, 1867 (Crustacea: Decapoda: Brachyura: Gecarcinidae), with description of a new cavernicolous species from the Philippines

Abstract

The taxonomy of the gecarcinid land crabs of the genus Discoplax A. Milne Edwards, 1867, is revised, and its differences with the related genus, Cardisoma Latreille, 1828, enumerated. Discoplax had been separated from Cardisoma primarily by its elongated ambulatory legs, but as this is not a reliable generic character, many authors have regarded both names as synonyms. However, a number of new differences (antennal structure, orbits, carapace, thoracic sternal and abdominal characters) show that both are distinct genera. The genus Discoplax now contains four species, the type species D. longipes A. Milne Edwards, 1867, D. hirtipes (Dana, 1852), D. rotunda (Quoy & Gaimard, 1824), and a new species, D. gracilipes, from the Philippines. Discoplax gracilipes is allied to D. longipes but can immediately be distinguished by its relatively longer ambulatory legs and smoother carapace. A key to the known Discoplax species is provided.