Larval shell development of the northern tuatua, Paphies subtriangulata (Bivalvia, Mesodesmatidae)

Abstract

The larval shell development of Paphies subtriangulata is described from larvae reared to settlement in the hatchery. Externally the larval shells of P. subtriangulata are very similar to those of Paphies ventricosa and, to a lesser extent, Paphies australis. Internally the hinge structures of the late‐stage larvae of P. subtriangulata, P. ventricosa, and P. australis are sufficiently different to distinguish the species. The spatulate tooth and the peg tooth of P. ventricosa are absent in P. subtriangulata and P. australis; the ligament of P. australis is posterior to the provinculum and central in P. ventricosa and P. subtriangulata. Straight‐hinge stage larvae of P. subtriangulata were 88–143 μm long and 67–117 μm high and umbo stage larvae were 125–265 μm long and 97–223 μm high. The larvae settled in about 17 days from a length of 230 μm.

Keywords:

• bivalve larvae
• Mesodesmatidae
• larval shell development
• larval morphology