Volvulella sp.

Valdés, Ángel, 2008, Deep-sea “ cephalaspidean ” heterobranchs (Gastropoda) from the tropical southwest Pacific, Mémoires du Muséum national d'Histoire naturelle 196, pp. 587-792 : 753-754

Volvulella sp.

Figs 81E, 83

MATERIAL EXAMINED. — Philippines. ESTASE 2: stn CP 2, 14°05’N, 120°02’E, 2050 m, 7 dd; stn CP 6, 04°38’N, 119°49’E, 2570 m, 13 dd (Fig. 81E) .

DISTRIBUTION. — Known only from the Philippines (Fig. 83), in 2050-2070 m .

DESCRIPTION. — Shell morphology. Length 6 mm, width 3 mm (largest specimen examined). Shell solid, oval, with convex sides (Fig. 81E). Only 1 whorl visible, forming the entire shell. Anterior end of the shell rounded. Umbilicus closed. Aperture long, wide anteriorly, narrowing abruptly at about 1/5 of its length. At its apical end, the aperture bends over the apex of the shell and the parietal wall forms a short extension that completely covers the apex. Columellar margin slightly twisted. Sculpture of numerous, faint and densely concentrated growth lines all over the shell surface. Colour uniformly dirty white.

Anatomy. Unknown. All shells collected lacked soft parts.

REMARKS. — Volvulella sp. is a deep-water species, the first member of the genus found below 1500 m. Its shell morphology resembles that of Volvulella opalina (A. Adams, 1862) , a shallower species from Japan (Hori 2000c). They differ in the presence of distinctive spiral grooves in V. opalina that are absent in Volvulella sp.

Because all the specimens of this species are empty shells collected from the same locality, and species of this genus show considerable shell variability, Volvulella sp. is not named, pending availability of more material.