Larval development of the cockle Chione stutchburyi (Bivalvia: Veneridae) reared in the laboratory

Abstract

Larvae of the New Zealand cockle Chione stutchburyi (Wood, 1828) reared to settlement in the laboratory are described. They are characterised by dissimilar shoulders with a large, broadly rounded anterior shoulder and end, and broadly rounded umbo, typical of the Veneridae. Setting occurred after 20 days at a minimum length of 180/µm. Shell dimensions increased linearly during larval development but hinge length did not. The L:H ratio decreased from 1.27 at L = 100 to 1.1 at L = 200 and the L:D ratio from 1.95 at L = 100 to 1.59 at L = 200. An SEM study revealed that the larval hinge is characterised by a toothed provinculum forming a broad medial projection on the right valve, opposing two projections on the left valve. Conspicuous flanges on the anterior and posterior shoulders of the left valve fit into corresponding grooves of the right valve.