Alatajassa (Amphipoda, Corophiidea), a new genus from the Pacific coast of North America

摘要

Alatajassa, a new genus of ischyrocerin corophiidean amphipod comprising two species has been discovered on the coast of Pacific North America. Alatajassa similis n. sp. has been found from California to Alaska (41 degrees N 124 degrees W-56 degrees N 134 degrees W) and Alatajassa diversa n. sp. from Amchitka Island, Alaska (51 degrees N 179 degrees E). Alatajassa is so named because of the wing-like expansions on the ischium of gnathopods 1-2 and pereopods 5-7. The genus is unusual in the Ischyrocerini in having long spinous processes extending ventrally from the peduncles of uropods 1 and 2, a stout, uniramous uropod 3, and sexual dimorphism posteriorly rather than anteriorly.