Biodiversity & Conservation

A bivalve mollusc - Thracia villosiuscula

Thracia villosiuscula

Image National Museum Wales - External view of Thracia villosiuscula valve. Image width ca 3 cm.
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Distribution map

Thracia villosiuscula recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

Why do the maps differ?

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Thracia villosiuscula is not listed under any importance categories.

Taxonomy icon Taxonomy Taxon English term
Phylum Mollusca Snails, slugs, mussels, cockles, clams & squid
Class Bivalvia Clams, cockles, mussels, oysters, and scallops
Authority (Macgillivray, 1827)
Recent synonyms None
Map icon Recorded Distribution in Britain and Ireland Reported from most parts of the British Isles but uncommon. The extent of distribution is uncertain because of the difficulty of separating Thracia villosiuscula from Thracia phaseolina.
Habitat information icon Habitat information Thracia villosiuscula burrows deeply in coarse sands and coarse fine gravels from the lower shore and shallow sublittoral to depths of about 55 m.
Text page icon Description Thracia villosiusucla is a rather flat sub-rectangular bivalve. It can be up to 3 cm long and shell white in colour and quite brittle. The surface of the shell has fine granulation and this can be seen with a X10 hand lens. The shiny covering layer of shell (periostracum) can be brown and sometimes reddish-brown. The posterior margin is obliquely truncated and slightly gaping. The beak (umbo) of the left valve sits in a hole in the beak of the right valve, and the right valve is slightly larger and more convex than the left. The bivalve does not contain either cardinal or lateral teeth.
Identifying features
  • Brittle, white bivalve up to 3 cm long.
  • Obliquely truncate posterior margin, slightly gaping.
  • Right valve slightly larger and more convex.
  • Umbo of left valve sitting in a hole in the umbo of the right.
  • Hinge line with a small triangular chondrophore but neither cardinal or lateral teeth are present.
  • Proportionally longer posterior hinge line.
Additional information icon Additional information Difficult to distinguish from Thracia phaseolina but can be told apart by finely granular shell surface, granulations visible with X10 hand lens.

This review can be cited as follows:

Anna Neish 2005. Thracia villosiuscula. A bivalve mollusc. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 24/05/2013]. Available from: <http://www.marlin.ac.uk/speciesinformation.php?speciesID=4469>