Orchomene nanus

(Kröyer, 1846)

Description:
Urosome segment 1 with a small depression on the dorsal margin, more marked in male than female: epimeral plate 3 posterodistal angle rounded, posterior margin smooth. Head with the lateral lobes prominent, broadly rounded in female, narrower in male: eyes large especially in male, oval. Antenna 1 peduncle article 1 extremely large and robust, articles 2 and 3 strongly compressed, flagellum about 9-articulate in female, up to 12-articulate in male; accessory flagellum 3-articulate with article 1 very large. Antenna 2 in female only slightly longer than 1 flagellum about 11-articulate, in male up to twice length of 1, about 20-articulate. Antenna 1 and 2 in male with calceoli. Propodus and carpus of gnathopod 1 about equal length, propodus narrowing slightly to small transverse palm delimited by pair of large spines. dactylus longer than the palm with a distinct tooth on the inner margin. Gnathopod 2 minutely subchelate, propodus half the length of the carpus, broadly oval, setose. Uropod 3 in female with the outer ramus longer than the inner one, with two to four setae on the inner margin: in male the outer ramus with several long plumose setae on the inner margin. Telson cleft to about three-quarters length, each lobe with one apical and one to three lateral spinules.

Size:
Up to 5 mm.

Colour:
Greyish or white.

Habitat:
Depth range from 0 to 250 metres; often found on carcasses of dead crabs.

Distribution:
North Atlantic, North Sea; coast of Europe from southern Norway to Spain: also Senegal.

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