Females: two (as opposed to three in other species) very wide and rounded segments of the urosome; no armature on metasome or urasome
Males: Characteristic structure of C5 (see picture)
Bering Sea, Chukchi Sea, Sea of Japan, Tokyo Bay, Hokkaido, Aleutian Islands, Gulf of Alaska, Vancouver Island
Coastal, brackish. Diffusion possible by ship's ballast waters
Female: Rostral filaments present. Corners of 5th thoracic segment rounded, the thorax and abdomen carry no armature. Abdomen 2.5 times shorter than the metasome. Urosome contains two segments (second and third fused) which are very swollen, rounded. Caudal rami also very rounded, filaments short with a widened proximal end. P5 uniramous, 2-segmented.
Male: Urosome contains 5 segments, caudal filaments have normal structure. The distal segment in P5 contains a long apical spine and a lateral filament which is longer than the segment.
Females: 2,00-2,70
Males: 1,8-2,10
