Crangon allmanni

Kinahan, 1857

Description
Rostrum unarmed, about twice the length of the eye, triangular with rounded apex. Median line of carapace with anteriorly directed spine in anterior quarter; antennal, pterygostomian and hepatic spines present.
Stylocerite acutely pointed, about 0.4 x length of antennular peduncle. Apical spine of scaphocerite exceeding the lamellar portion. Third maxilliped 1-1.2 x length of scaphocerite; exopod and arthrobranch present.
Mandible with molar process only, teeth sharply pointed.
Pereiopod 1 sub-chelate, stout.
Pereiopod 2 extends to three-quarters of length of propus of pereiopod 1; dactyl of pereiopod 2 about a quarter the length of the propus. Pleonite 6 with a deep longitudinal dorsal groove and two parallel carinae. Endopods of pleopods 2-5 two-segmented, without appendix interna.
Telson with two pairs of small lateral spines.

Remarks
This species closely resembles Crangon crangon, but is slightly slimmer and is easily distinguishable by the groove in pleonite 6.

Size
Length up to 75 mm, usually less.

Colour
Normally brownish-grey.

Ecology
Occurs on muddy or sandy substrates. Hyperbenthic species, may swim up at night, mostly confined to the nepheloid layer; adults may get caught with pelagic sampling. Ovigerous females from December to July, although most have stopped breeding by May.

Depth range
Down to about 20-250 m, occasionally down to 360 m.

Distribution in the North Sea
All North Sea; larvae reported from CPR areas D1, D2, C1, C2, B2 (Lindley, 1987) CPR/NorthSea.

World distribution
Ranges from the White Sea southwards to the Bay of Biscay.

[Mainly after Smaldon, 1993]

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