Malacological Society of Australasia

Molluscan Research

Volume 18, Issue 1: 30 April 1997

Large Trachycardiinae from the Indo-West Pacific: The group of Vasticardium orbita (Broderip & Sowerby, 1833) (Mollusca, Cardiidae).

J. Vidal

Attach au Museum National d'Histoire Naturelle, Laboratoire de Biologie des Invertbrs, Marins et Malacologie, 55 rue Buffon, 75005 Paris, France.

Two closely related species of Trachycardiinae from the Indo-West Pacific belonging to the Vasticardium orbita complex are revised. Young specimens are very similar shell morphology but adult shells differ in general shape and rib structure. Based on these ontogenetic changes, and also on rib count, which appears to be stable character, two species are recognised: (1) Vasticardium orbita(Broderip & Sowerby, 1833), with a mainly Pacific distribution and four subspecies: orbita, hawaiiensis, mendanaense, and philippinense and (2) Vasticardium luteomarginatum(Voskuil and Onverwagt, 1991), with a primarily Indian Ocean distribution and three subspecies: luteomarginatum, marerubrum, and insulare, the last of which is herein described as new. The two species are usually easy to separate, but some specimens are difficult to differentiate. The apparently allopatric distribution of the two species raises the possibility that a single species, with discrete geographical subspecies, is involved.

pp. 11-32.