Pinna deltodes Menke newly described and differentiated from P. bicolor Gmelin (Bivalvia, Pterioida)

Abstract

Pinna deltodes Menke is a valid Indo-Pacific species of Pinnidae morphologically similar to P. bicolor Gmelin. It can be distinguished from P. bicolor in Australia by the presence of regular, sharply defined, pinkish-buff lateral bands of subepithelial gland cells along the inner fold of the posterior mantle margin and by the position of the posterior adductor muscle scar at the posterior edge of the dorsal nacreous layer. The subepithelial gland cells are coarsely granular; they are not acid or neutral muco-polysaccharides (mucins) or muco-glycoproteins (mucoids). The preferred habitat of P. deltodes is a hard substrate, either within cobble flats or beneath boulders, coral blocks, and bombies. The species extends off eastern Africa to eastern Australia and as far north as Pakistan and probably the Red Sea, from the intertidal zone to 14 0m.