Abstract
Two species of the genus Kamaka (Crustacea: Amphipoda: Kamakidae) are described from Japan. Kamaka biwae Ueno, 1943 occurred only in Lake Biwa, Shiga Prefecture, and the morphological characters and coloration of the present material agree with Ueno's description except for the shape of coxa 5. Kamaka morinoi sp. nov. was collected from brackish and freshwater areas in Miyagi, Fukushima, Ibaraki, Tottori, and Shimane Prefectures. Its morphological features closely resemble those of K. biwae, but K. morinoi can be distinguished from K. biwae by the following points: (1) higher numbers of plumose setae on the posterior margins of pereopods 5-7, (2) smaller maximal body length, and (3) male coloration (especially in coxa 1). The distributions of the two species suggest that K. biwae speciated from K. morinoi or that they share a common ancestor.
