Notes on the taxonomy of Frevillea A. Milne-Edwards, 1880 (Crustacea, Brachyura, Goneplacoidea), with the description of a new genus for F. sigsbei A. Milne-Edwards, 1880

The identities of the Western Atlantic brachyuran crabs Frevillea barbata A. Milne-Edwards, 1880, F. rosaea A. Milne-Edwards, 1880, F. tridentata A. Milne-Edwards, 1880, and F. sigsbei A. Milne-Edwards, 1880, originally placed in Goneplacidae MacLeay, 1838, are clarified on the basis of the examination of type material as well as of additional specimens. The correct identity of the type material of the four species is resolved. A new genus, Diuplax n. gen., is described for F. sigsbei, which had previously been transferred to Goneplax Leach, 1814 (family Goneplacidae). The new genus is distinguished from Goneplax s. str. by having a short cheliped merus that possesses a low submedian tubercle on its dorsal margin (elongated merus with a distinct short submedian spine on its dorsal margin in Goneplax s. str.) and the unarmed dorsal margin of the meri of the ambulatory legs (with distinct subdistal spine in Goneplax s. str.). Frevillea barbata and F. rosaea are now in the Euryplacidae Stimpson, 1871, F. sigsbei is in Diuplax n. gen. (Goneplacidae, Goneplacoidea MacLeay, 1838), whereas F. tridentata is in Trapezioplax Guinot, 1969 in Pseudorhombilidae Alcock, 1900 (Xanthoidea MacLeay, 1838).