(Milne Edwards, 1828)
Body up to 7 mm (excluding the uropods). Cephalothorax slightly longer than broad, with a narrow, parallel-sided, short, rostrum, produced apically into a single thin spine. Eyes present. Epistomal spine absent.
Medio-ventral pleonal spines present. Antero-lateral margins of pereionites not produced. Pleonal epimera posteriorly deflected at apices, each apex with a spine. Pleotelson shorter than the pleon.
The chelipeds are markedly sexually dimorphic: in the male they are robust with a prominent tooth on the inner margins of the propodus and dactylus; in the female the chela is more slender and without teeth.
It is found on the mid to lower shore under stones, in rock crevices and in muddy gravel. It also occurs in kelp holdfasts, coralline algae and Zostera roots.
Recorded from southern and north-eastern coasts of England, the Channel Islands, the Isles of Scilly, and eastern Scotland. Records also exist for the French and Italian coasts.