ARCIDAE, Lamarck, 1809

Oliver, P. Graham & Holmes, Anna, 2004, Cryptic bivalves with descriptions of new species from the Rodrigues lagoon, Journal of Natural History 38 (23), pp. 3175-3227 : 3176

ARCIDAE

In this paper the numerous subgeneric taxa available within Barbatia sensu lato are not adopted but the genus Acar is recognized. There is currently no modern revision of any of the Arcoidea and without this the use of the available subgeneric names is fraught with uncertainty. Given this premise the fauna of Rodrigues contains six species of Barbatia : B. lacerata (Bruguière, 1789) , B. amygdalumtostum (Röding, 1798) , B. parva (Sowerby, 1833) , B. revelata ( Deshayes, 1863) and two small cryptic species which are described in detail below. Barbatia lacerata and B. amygdalumtostum are relatively large (to 50 mm) and are the most common on hard substrates within the lagoon. Barbatia caelata (Reeve, 1844) is also large but has been found only once, under coral rubble at about 5 m depth. Barbatia parva is a smaller species (to 20 mm) and has only been found alive occasionally and on the reef crest or front. Juveniles of these Barbatia species are not described but must be included in any comparisons of small cryptic taxa. Surprisingly the widespread Indo-Pacific taxa of the Barbatia foliata (Forsskal, 1775) complex have not been found on Rodrigues and consequently their juveniles are not included here.