Notes on the Indo-West Pacific shrimp genus Athanopsis Coutiere, 1897 (Crustacea, Decapoda, Alpheidae), with the description of a new species associated with echiurans (Annelida, Thalassematidae)

The Indo-West Pacific alpheid shrimp genus Athanopsis Coutiere, 1897 is briefly reviewed. Athanopsis platyrhynchus Coutiere, 1897, the type species, is reassessed using Coutiere's illustrations and morphological notes scattered throughout his monograph of the family Alpheidae (Coutiere 1899). Athanopsis brevirostris Banner & Banner, 1981, originally described on the basis of a single immature specimen missing both chelipeds, is reported and illustrated based on fresh material from Madagascar and southern Japan. Athanopsis gotoi sp. nov. is described based on two fresh specimens from southern Japan, both found associated with thalassematid echiurans, and an additional, older museum specimen from Indonesia. The colour patterns of A. brevirostris, A. gotoi sp. nov., A. saurus Anker, 2011, A. rubricinctuta Berggren, 1991, and A. australis Banner & Banner, 1982, are contrasted to facilitate their identification in the field. A morphology and colour based key to all presently known species of Athanopsis is also provided.