May be distinguished from other species of the genus by the 3rd endopodite of P4 with the marked difference in length of the terminal spines, plus the proximal point of insertion of the outer spine, 1/3 the length of the segment from the terminal spines
Arctic, Norwegian Sea
Bathypelagic
Female:
Cephalothorax about 2.1 times longer than the abdomen. Exosceleton very fragile, weakly sclerotized (often damaged in collections). Genital segment with gonopores near midregion of the dorsal surface, each area with a setule. Caudal rami with dorsal seta more than 2 times longer than the innermost terminal seta, which is approximately equal in length to the caudal rami.
P1-P4 with armature similar to O. borealis. P2 and P3 endopodites end in conical projections between the 2nd and terminal spines, P4 without such projection. P5 small, not delimited from the 1st abdominal segment, with 2 terminal setae, the inner of which is slightly shorter and spiniform.
P6 probably represented by spiniform setule near the gonopores.
Male:
A1 lacks a distal seta on the 3rd segment. Swimming legs as in female, except P2 endopodite with shorter terminal spines. P5 not delimited from the 1st abdominal segment, with 2 terminal setae. P6 probably represented by posterolateral flap on the ventral surface of the genital segment.
