Heterorhabdus norvegicus (Boeck 1872)

Body very clear and colorless, with a light yellow tint

Body more slender than in other species of the genus.

Central Arctic Basin, Norwegian coast, Greenland Sea, North Atlantic, Gulf of Maine

Oceanic epi-meso-bathypelagic species. In the Arctic is found at depths of 50-1000 m, in the Greenland Sea from 100 to 3000 m, in the Atlantic Ocean at greater depths.

Females:
Body slender, posterior corners of the last thoracic segment are rounded, protrude slightly when looking from the side. Abdomen is less than 2 times shorter than the cephalothorax, the genital segment is as long as the combined length of the next two segments and a third of the anal segment. Caudal rami slightly asymmetrical and 1.5 times longer than the anal segment. The ventral protuberance of the genital segment has a large valve, the dorsal surface of the segment is indented in the distal half. A1 are slightly longer than the body. Teeth of Md similar in size, the right mandible has 5 teeth, the left – 4. The distal part of Mxp1 with stout, practically straight serrated chaetae, Mxp2 with a long curved bare chaeta on the first basipodite. The distal segment of swimming legs widened, but less so than in other species of the genus, internal chaetae are present. Outer spines of the first and second segments of the exopodite of P5 are small and curved. The largest chaeta has an obvious double-spiral serration, its length is greater than the width of the segment by 3 times.

Males: Body shape is similar as in female. The abdomen is 2.3 times shorter than the cephalothorax, the left A1 is geniculate. The inner growth of the second basipodite of the right P5 is curved inward, the first segment of the exopodite with a small inner protrusion, the second segment with a complex, double-tipped short protrusion.

Female: 2,65-4,60 mm
Male: 2,58-4,20 mm

Gulf of St. Lawrence (unspecified region); lower St. Lawrence estuary

pelagic