Volvulella, Newton, 1891

Valdés, Ángel, 2008, Deep-sea “ cephalaspidean ” heterobranchs (Gastropoda) from the tropical southwest Pacific, Mémoires du Muséum national d'Histoire naturelle 196, pp. 587-792 : 748

Genus VOLVULELLA Newton, 1891

Volvulella Newton, 1891: 268 [Replacement name for Volvula A. Adams in Sowerby, 1850].

Synonym:

Volvula A. Adams in Sowerby, 1850 [in 1848-50]: 558 [non Volvula Gistel 1848 – Diptera ]. Type species: Bulla acuminata Bruguière, 1792 [Recent, northeastern Atlantic], by subsequent designation of Menke (1854).

DIAGNOSIS. — Shell morphology. Shell external, thin, delicate, ovate, with only 1 whorl visible. Aperture longitudinal, long, anteriorly rounded, bending apically over the apex of the shell. Parietal wall forming an extension (a spine in some species) that covers the apex. Operculum absent.

Anatomy. Short headshield, with the posterior end divided into 2 short projecting lobes. Jaws, radula and gizzard plates absent.

REMARKS. — Most authors have used the name Rhizorus Montfort, 1810 to refer to this genus (see Thompson 1976). However, Harry (1967) indicated that Rhizorus Montfort, 1810 is a different genus. He also mentioned that Volvula A. Adams in Sowerby, 1850 is the oldest available name for the taxon treated herein, but it is preoccupied by Volvula Gistel, 1848 (Diptera) . Volvulella Newton 1891 , which is a replacement name for Volvula A. Adams in Sowerby, 1850, is therefore the valid name. Marcus & Marcus (1960) placed this genus in the Retusidae because of the similarities with Retusa in the shape of the headshield and larval shell, as well as in the absence of jaws and radula.