Pyrunculus, Pilsbry, 1895

Valdés, Ángel, 2008, Deep-sea “ cephalaspidean ” heterobranchs (Gastropoda) from the tropical southwest Pacific, Mémoires du Muséum national d'Histoire naturelle 196, pp. 587-792 : 743-744

Genus PYRUNCULUS Pilsbry, 1895

Pyrunculus Pilsbry, 1895 [in 1895-96]: 181. Type species: Bulla pyriformis A. Adams in Sowerby, 1850 [Recent, Indo-Pacific], by monotypy.

Synonym:

Sao H. & A. Adams, 1854 [in 1854-58]: 21 [non Sao Billberg, 1820 – Crustacea]. Type species: Bulla pyriformis A. Adams in Sowerby, 1850 [Recent, Indo-Pacific], by monotypy.

DIAGNOSIS. — Shell morphology. Shell external, fragile, pyriform, with only 1 whorl visible. Aperture longitudinal, as long as

the shell, wider anteriorly, narrowing abruptly posteriorly. Columella thickened, with a small tooth. Operculum absent. Anatomy. Digestive system with 3 unequal and tuberculate gizzard plates. There is no radula or jaws.

REMARKS. — The genus Pyrunculus is anatomically similar to Retusa , but differs in the shape of the gizzard plates, which have a smaller number of tubercles in the former. Other differences include the shape of the shell, much shorter and more deeply umbilicate apically in Pyrunculus than in any species of Retusa . Therefore the genus Pyrunculus is here maintained as valid.