Diastylis tumida

(Lilljeborg, 1855)

Description
Carapace as broad as long, smooth in the female or with some minute denticles or more usually with a pair of small teeth one behind the other on either side of the frontal lobe; in the male the lateral line runs near to the lower margin from the subrostral angle to the rear of the carapace. The pseudorostrum is not very long. The posterolateral corners of pereionite 5 are rounded in the female, produced to an acute point in the male. The eye is prominent, with lenses. Basis of pereiopod 1 with a row of spines, shorter than remaining segments together; the carpus is shorter than the propodus, which is about twice as long as the dactyl. The carpus of pereiopod 2 is nearly as long as the propodus and dactyl together. The telson is shorter than the uropod peduncles and has eight or nine pairs of lateral spines; its distal part is about as long as or a little shorter than the proximal part.
Telson long, postanal part narrowed, with several pairs of lateral spines.

Size
Length up to 10 mm.

Ecology
Shelf to bathyal.

Depth range
Down to about 25 and 1400 m.

Distribution in the North Sea
Northern North Sea, Skagerrak.

World distribution
Has been collected between N Norway and the Bay of Biscay and from the Azores, including a few records from NE England, the Clyde area and Liverpool Bay off the British Isles.

[After Jones, 1976]

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