First Record of Gammarus koreanus (Crustacea, Amphipoda, Gammaroidea) from Japan, Based on Morphology and 28S rRNA Gene Sequences

Abstract

Gammarus koreanus Ueno, 1940, which was originally described from the Korean Peninsula, is recorded from freshwaters of the Goto Islands, Japan. This is the first record of its occurrence in Japan. Molecular analyses using partial sequences of the 28S rRNA gene strongly support the identity of Japanese populations with G. koreanus. The Japanese specimens differ from the original description of this species in the following features: antenna 2 lacking calceoli, inner margins of inner and outer rami of uropod 3 with plumose setae, and outer margin of outer ramus of uropod 3 without plumose setae. These differences are regarded as intraspecific variation.