Pleurogonium (Crustacea : Isopoda : Asellota : Paramunnidae) from Hokkaido, Northern Japan, with Descriptions of Two New Species

Abstract

Three species and one subspecies of Pleurogonium, including two new to science, are reported from Akkeshi, Hokkaido, as the first record of this genus from northern Japan. Pleurogonium bifolium sp. nov. has bilobed coxal plates and posterolaterally projecting pereonites 2-4 as in P. godeevae Kussakin, 1962, but it is distinguished from the latter in having a frontally bilobed head, pereonite 1 with a pair of stout lateral projections, and a pleotelson with its greatest width anteriorly. Pleurogonium hispidum sp. nov. differs from its congeners by the presence of a trilobed frontal margin of the head and a pair of mid-dorsal setae on all ten segments from head to pleotelson. Pleurogonium angustum Kussakin, 1972 and P. inerme orientale Kussakin, 1962 are recorded from Japan for the first time.