Description: A solid bivalve with 2 equal valves and a broadly oval outline. It reaches around 3 cm in length and is white with a dark brown to red-brown periostracum, which has a mesh-like structure. The outer surface of the shell is covered in 25-30 broad concentric ridges and concentric lines. Growth stages are not clear. 2 cardinal teeth in right valve, anterior one is broad and highly variable in shape sometimes even bifid, while posterior is thin; 3 cardinal teeth in left valve, the posterior is very small and often broken.

Habitat: Sandy mud and gravel from around 5 - 150 m.

Distribution: Scattered records from around Britain and Ireland, mostly recorded on the north and NE coasts.

Similar Species: Could be confused with Tridonta borealis.

Key Identification Features:

• Dark brown to red-brown periostracum.
• 25-30 broad concentric ridges and some concentric lines.
• 2 cardinal teeth in right valve, anterior very variable sometimes even bifid.
• 3 cardinal teeth in left valve, posterior of which is very small and often broken.

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

iNaturalist: Tridonta elliptica at iNaturalist World Species Observations database.

GBIF data for Tridonta elliptica

WoRMS: Tridonta elliptica at World Register of Marine Species. Accepted name: Tridonta elliptica (T. Brown, 1827). AphiaID: 152282.

Classification: Biota; Animalia; Mollusca; Bivalvia; Autobranchia; Heteroconchia; Archiheterodonta; Carditida; Crassatelloidea; Astartidae; Tridonta