(Hailstone, 1835)
Description
Rostrum narrow, unarmed, triangular with rounded apex, extending to about 0.4 x length of eye.
Carapace with two anteriorly-directed spines on median line; antennal and pterygostomian spines present.
Stylocerite broad diamond shape, rounded at corners. Apical spine of scaphocerite equal to, or slightly longer than, lamellar portion. Third maxilliped 1-1.33 x length of scaphocerite; exopod and arthrobranch present.
Mandible with molar process only, teeth with rounded tips.
Pereiopod 1 sub-chelate, stout. Pereiopod 2 extends to proximal quarter of propus of pereiopod 1. Dactyl of pereiopod 2 is 0.66 x length of propus, often a little more. Endopods of pleopods 2-5 two-segmented, without appendix interna.
Telson with two pairs of small lateral spines.
Remarks
The variety P. bispinosus neglectus differs in having the second spine on the median line of the carapace reduced to a tubercle, the carapace is also smoother than in P. b. bispinosus. Forms intermediate between the nominate species and its variety have been recorded.
Size
Length up to 26 mm.
Colour
A pale mottled grey with reddish hue.
Ecology
Usually on muddy or sandy substrates. It is not certain whether this species never swims up into the water column; adults may get caught with pelagic sampling. Ovigerous females occur from May to August, although there are occasional records from earlier months.
Depth range
Down to about 5-360 m, normally to 100 m.
Distribution in the North Sea
All North Sea.
World distribution
Ranges from Iceland, Faeroes and SW Norway southwards to the Azores and into the Mediterranean.
[Mainly after Smaldon, 1993]