Nematocarcinus ensifer

(S.I. Smith, 1882)

Description
Rostrum straight, slightly directed upwards, extending beyond antennular peduncle. Length variable from 1/3 to 3/5 of the carapace length. Rostrum with 32-31 dorsal spines, of which 8-10 lie behind the orbit; ventrally there are no spines on the rostrum, but a sereis of plumose setae is present.
Carapace with a marked cervical groove, continuing down- and forwards on both sides of the carapace; anteriorly a dorsal keel is present, becoming obsolete just anterior of the cervical groove. Carapace with supra-antennal and antero-lateral spines.
Eyes pyriform.
Antennular peduncle reaching slightly beyond halfway the antennal scale; antennular flagellum very long.
All pereiopods are very slender, P3-5 of enormous length. P1-4 with slender exopods, decreasing in size from P1 to P4; P5 without exopod.
Abdominal somites laterally compressed, without dorsal keel. Segment 3 somewhat dorso-posteriorly produced, extending over segment 4. Segment 6 strongly laterally compressed, more than twice the length of the fifth segment.
Telson with dorsal sulcus and dorso-laterally beset with 6-7 pairs of short spines. Telson narrowing evenly; apex with three pairs of spines.

Colour
Transparent pinkish white (in life); eyes with traces of red pigment, cornea black.

Size
Maximal body length of E Atlantic specimens 70-80 mm.

Depth range
Mesopelagic; ca. 200-1000 m.

Distribution in the North Sea
Possibly near the entrance of the northern North Sea.

World distribution
N Atlantic (probably with important differences between the W and E Atlantic populations); Mediterranean; N Indian and Pacific Oceans.

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