Obrussena, Iredale, 1930

Valdés, Ángel, 2008, Deep-sea “ cephalaspidean ” heterobranchs (Gastropoda) from the tropical southwest Pacific, Mémoires du Muséum national d'Histoire naturelle 196, pp. 587-792 : 599

Genus OBRUSSENA Iredale, 1930

Obrussena Iredale, 1930: 175 [Replacement name for Obrussa Iredale, 1925 ].

Synonym:

Obrussa Iredale, 1925: 269 [non Obrussa Braun, 1925 – Lepidoptera ]. Type species: Obrussa bracteata Iredale, 1925 [Recent, New South Wales, Australia], by monotypy.

DIAGNOSIS. — Shell morphology. Shell external, solid, oval, transversely sulcate; spire short. Aperture short and wide, anteriorly rounded. Inner lip simple, with no folds or teeth. Columella smooth, with no folds. Deeply umbilicate. Operculum present.

Anatomy. Radula composed of numerous denticulate and small teeth.

REMARKS. — Iredale (1925) introduced the genus Obrussa for the single species Obrussa bracteata Iredale, 1925 as a probable member of the Acteonidae . The radula of Obrussena contains numerous, denticulate lateral teeth similar to those of Acteon . Differences between these two groups include the shorter and wider shell, the smaller number of lateral teeth on each row of the radula and the more elongate tooth shape in Obrussena .

The genus Inopinodon Bouchet, 1975 also has a similar radular morphology, with the lateral teeth having several apical denticles or cups. However, Inopinodon has more than 60 lateral teeth ( Bouchet 1975), whereas Obrussena has less than 20. Also, the outermost teeth of Inopinodon are more elongate. Some members Tomlinula also have a similar radular morphology, with multidenticulate teeth (Marcus 1972), but with a larger number of tooth rows. It is possible that Obrussena will eventually be synonymized with another member of the Acteonidae , but since the rest of the anatomy remains unknown, this genus is provisionally maintained as valid within the Acteonidae until more information becomes available. The diagnosis of Obrussena has been extracted from the shell characteristics of the specimens here examined.