A new species of the thorid shrimp genus Eualus Thallwitz, 1892 (Crustacea: Decapoda: Caridea) from the Bering Sea, with notes on related species

Abstract

Examination of material from the Bering Sea led us to reevaluate the specific identity of a thorid shrimp taxon Eualus ratmanovi Makarov, 1941 (Decapoda: Caridea), originally described from the Bering Sea. From morphological comparison of available material, we came to a conclusion that E. ratmanovi is a junior subjective synonym of E. belcheri (Bell, 1855), and that E. belcheri is specifically distinct from E. gaimardii (H. Milne Edwards, 1837), not a subspecies of the latter. The material from the Bering Sea is here attributed to a new species, E. zarenkovi sp.n. The three species treated in this study are primarily differentiated by the development and shape of the middorsal protuberance on the third pleomere. Other distinguishing characters include the rostral shape and armature, the length and armature of the telson, the length of the antennular stylocerite, the length of the third maxilliped, and the proportion of the dactylus of the third pereopod. Many of these diagnostic characters are influenced by sexual dimorphism, requiring careful comparison according to the sex.