Description: As the name suggests this crab’s carapace is almost circular and reaches a size of up to 40 mm. The surface of the carapace is reddish-brown with some small grooves and ridges. There are three teeth between the eyes, with the middle one most pronounced. There are 9-10 (rarely 11) small, pointed teeth on each side of the carapace, which usually alternate in size, with the second and fourth being the smallest. There are dense bristles on the sides of carapace, limbs and towards the underside of the animal. Pincers are evenly sized and usually lighter in colour than the carapace. The walking legs are also usually lighter in colour.

Habitat: Recorded from 12 m to around 90 m on sand and gravel substrate.

Distribution: Found all around Britain and Ireland but rarely recorded from west coast of Ireland.

Similar Species: Could be confused with Atelecyclus undecimdentatus.

Key Identification Features:

• Almost circular carapace.
• 9-10 (rarely 11) small, pointed teeth on each side of carapace.
• Alternating size of teeth at side of carapace.
• Second and fourth set are usually the biggest.

Distribution Map from NBN: Atelecyclus rotundatus at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Atelecyclus rotundatus at iNaturalist World Species Observations database.

WoRMS: Atelecyclus rotundatus at World Register of Marine Species. Accepted name: Atelecyclus rotundatus (Olivi, 1792). AphiaID: 107273.

Classification: Biota; Animalia; Arthropoda; Crustacea; Multicrustacea; Malacostraca; Eumalacostraca; Eucarida; Decapoda; Pleocyemata; Brachyura; Eubrachyura; Heterotremata; Cancroidea; Atelecyclidae; Atelecyclus