Crabs of the subfamily Ethusinae Guinot, 1977 (Crustacea, Decapoda, Brachyura, Dorippidae) of the Indo-West Pacific region

Brachyuran crabs belonging to the subfamily Ethusinae Guinot, 1977, family Dorippidae MacLeay, 1838, are adapted to carry bivalve shells or other objects on their backs by using the hooked dactyli of their last two pairs of pereopods (P4 and P5), which are dorsally located and mobile. Most species inhabit deep water and are infrequently collected. The taxonomy of the 57 known Indo-West Pacific species of ethusines is revised. The subfamily consists of three genera: Ethusa Roux, 1830, with 30 species of which four are being described as new, Ethusina Smith, 1884, with 25 species of which eight are new, and Parethusa Chen, 1997, with two species of which one is new. Ethusa and Ethusina are worldwide in distribution while Parethusa is exclusive to the Indo-West Pacific region. Seven nominal species described by other authors were found to be junior subjective synonyms of other species: Ethusa major Chen, 1993, of Ethusa orientalis Miers, 1886; Ethusa makasarica Chen, 1993, of Ethusa hirsuta McArdle, 1900; Ethusa madagascariensis Chen, 1987, of Ethusa zurstrasseni Doflein, 1904; Ethusina investigatoris (Alcock, 1896) and E. alcocki Ng & Ho, 2003, of Ethusina robusta Miers, 1886; Ethusina insolita Ng & Ho, 2003, of Ethusina dilobotus Chen, 1993; and Ethusina saltator Ng & Ho, 2000, of Ethusina paralongipes Chen, 1993.