Revision of the family Euryplacidae Stimpson, 1871 (Crustacea: Decapoda: Brachyura: Goneplacoidea)

The family Euryplacidae Stimpson, 1871, traditionally included in the Goneplacidae MacLeay, 1838, is revised based on the examination of the type material of many of its species as well as unidentified and previously identified material from around the world. The revised family now consists of 31 species (including five that are described as new) belonging to 13 genera (including four that are described as new): Eucrate De Haan, 1835, with eight species, of which one is new; Euryplax Stimpson, 1859, with two species; Frevillea A. Milne-Edwards, 1880, with three species; Henicoplax n. gen., with five species of which three are new; Heteroplax Stimpson, 1858, monotypic; Machaerus Leach, 1818, with two species; Nancyplax Lemaitre, Garcia-Gomez, von Sternberg & Campos, 2001, monotypic; Platyozius Borradaile, 1902, monotypic; Psopheticoides Sakai, 1969, monotypic; Systroplax n. gen., monotypic; Trissoplax n. gen., with two species, of which one is new; Trizocarcinus Rathbun, 1914, with two species; Villoplax n. gen., monotypic; and Xenocrate Ng & Castro, 2007, monotypic. The genus Platyozius and Eucrate formosensis Sakai, 1974, are removed from the synonymy of Eucrate and E. alcocki Serene, in Serene & Lohavanijaya, 1973, respectively. Neotypes are selected for Heteroplax dentata Stimpson, 1858, and Pilumnoplax sulcatifrons Stimpson, 1858, two species described from Hong Kong that have a confusing taxonomic history. A neotype is also selected for Euryplax nitida Stimpson, 1859, described from the Florida Keys. Seven nominal species described by other authors were found to be junior subjective synonyms for other species: Eucrate affinis Haswell, 1882, E. costata Yang & Sun 1979, E. haswelli Campbell 1969, and Pseudorhombila sulcatifrons var. australiensis Miers, 1884, of Trissoplax dentata (Stimpson, 1858); Galene laevimanus (Lucas, in Jacquinot & Lucas, 1853) of Eucrate dorsalis (White, 1849); Heteroplax nagasakiensis Sakai, 1934, of H. transversa Stimpson, 1858; and Pilumnoplax sulcatifrons Stimpson, 1858, of Eucrate crenata (De Haan, 1835). Eight euryplacid genera are exclusively found in the Indo-West Pacific region (except one species introduced in the Mediterranean), one is exclusive to each the Eastern Atlantic and Tropical Eastern Pacific regions, three to the Western Atlantic region, and one genus has both Western Atlantic and Tropical Eastern Pacific species.