Barbatia lacerata (Linnaeus, 1758)

Oliver, P. Graham, Holmes, Anna, Killeen, Ian, Light, Janice & Wood, Harriet, 2004, Annotated checklist of the marine Bivalvia of Rodrigues, Journal of Natural History 38 (23), pp. 3229-3272 : 3232

Barbatia lacerata (Linnaeus, 1758)

Habitat. Attached by a strong byssus to dead corals, coral rubble and occasionally to basalt rocks.

Distribution. From low in the littoral to 10 m in lagoon channels. This species can be abundant and is the dominant bivalve in the rubble fields of the southern lagoon as well as living in turbid areas such as Baie du Nord and Pointe Palmiste. It is not found in the reef front rubble beds and appears to be positively linked with waters with a high suspension load. It can co-occur with B. amygdalumtostum (see below) but that species is more often found in clearer water. A detailed comparison of the distribution of these two species might result in finding biological indicators of water turbidity.

Remarks. The widely separated rows of spicate, periostracal bristles distinguish B. lacerata from B. amygdalumtostum .

B. lacerata is very similar to B. setigera ( Reeve, 1844) but differs in the form of the periostracum. In both species the periostracum consists of widely spaced radial rows of large bristles with a series of shorter lamellae between them. In B. lacerata the bristles are less robust and the lamellae are moderately long with weak or obsolete projecting hairs. In B. setigera the large bristles are more closely spaced and robust and the lamellae are short with strong projecting hairs. These observations agree with Kilburn (1983) but we would emphasize the form of the intermediate lamellae rather than the form of the large bristles as the better discriminatory character.

On Rodriguan specimens the posterior, internal coloration of B. lacerata is purple black whereas on Mauritius all examined specimens were brown.

Range. Restricted to tropical south-east Africa and Mascarenes [M].

Figured specimen. 46.32 mm, NMW.Z.1999.073.00046.