A significant and unappreciated intertidal mytiloidean genus: the biology and functional morphology of Brachidontes puniceus (Bivalvia: Mytilidae) from the Cape Verde Islands

Brachidontes puniceus (Gmelin 1791) occurs on all the islands of the Cape Verde Archipelago and along the West African coast from Mauritania to Ghana. The species is morphologically, in terms of its acutely heteromyarian form, strong byssal attachment, stout ligament, thickened shell ornamented with obliquely radial ribs, marginal denticles and strongly developed hinge teeth, intimately adapted to life in the tropical rocky intertidal. Internally, B. puniceus has large ctenidia and tiny labial palps that enhance suspension feeding in, generally, nutrient-deficient tropical waters. As with its congeners distributed throughout the tropics and subtropics globally, B. puniceus is probably also physiologically and reproductively opportunistic such that it can readily colonise hard intertidal substrata. In comparison with boreal mytilids, notably species of Mytilus, the widely successful, abundant and diverse tropical species of Brachidontes remain poorly studied and understood, anatomically and physiologically largely uninvestigated and ecologically unappreciated. This study provides the basic information necessary to allow this situation to be rectified.