(M. Sars, 1869)
Description
— Generic features. Statocyst usually present. Pleopods of female reduced, rudimentary; of male variable. Endopod (and exopod) of uropod without spines. Outer margin of antennal scale without setae; ending in terminal tooth. Eyeplates quadrangular, outer corners rounded, margins not serrulated. Eyes often rudimentary in the form of flat plates without definite stalks. Telson rounded. Lateral margins of telson and apex armed with a graduated series of spines and a pair of median setae. Marsupium consists, as in the Genus Pseudomma, of two well-developed incubatory brood lamellae.
— Species. Body somewhat robust. Carapace large and deeply produced laterally; cephalic region slightly inflated; anterior margin broadly rounded without rostral projection. Posterior border emarginate leaving most of the last thoracic somite exposed in dorsal view.
Eyes rudimentary in the form of two large, separate, rhomboidal plates.
Antennular peduncle short and robust, outer distal corner of first segment produced as in the Genus Erythrops and tipped with three of four plumose setae; middle segment very short;
Antennal peduncle slightly shorter than the antennular peduncle and much more slender, four-segmented, with the second short and bent upward from the plane of the first segment; third swollen, overhanging the second segment and bent downward from it so that in lateral view the peduncle has a peculiar distorted appearance.
Uropod with exopod about twice as along as the last abdominal somite and half as long again as the slender, tapering endopod which bears a single blunt short spine on the inner ventral surface in the region of the statocyst.
Telson linguiform, longer than the last abdominal somite; lateral margins tapering slightly to the bluntly rounded apex; posterior two-thirds of each lateral margin armed with a regularly graduated row of 26-27 spines which lengthen posteriorly and merge into the long spines at the apex; pair of median plumose setae present.
Colour
Anterior portion of body transparent and colourless except for the eyeplates which are covered with very minute red specks of pigment and appear rosy red in colour. The large gut shows through the integument as a reddish mass and the yellow liver is also cleurly visible. The abdomen is sparsely covered with minute, evenly distributed, red specks.
Size
Length of both sexes 18 mm.
Depth range
Hyperbenthic, bathypelagic; usually from 380 to 1425 m, with the greatest numbers occurring around depths of 600 m. Normally the species lives resting on the sea bottom making only short occasional excursions into the lower levels of water just above the floor.
Remarks
Pleopods of the male very large and well developed, biramous, natatory.
Distribution in the North Sea
Eastern northern North Sea, W off Norway, Skagerrak.
World distribution
N North Atlantic, N North Pacific; coastal to bathyal. N North Atlantic, N North Pacific; coastal to bathyal. Davis Strait, off west, south and east coasts of Greenland, south of Iceland, East Finmark, many records form Norwegian waters from Vardø to Oslofjord, Denmark, and from the Bay of Biscay.
[After Tattersall and Tattersall, 1951]