Seguenzia donaldi Ladd, 1982

(Figures 8–9)

1982 Seguenzia donaldi nov. spec.—Ladd: p. 32–33, pl. 35, figs 9–15.

Material. Anda 6 (6); AndaDeVos (29); AndaClif3 (10).

Characterization. Shell relatively broad conical to trochiform, H 1.9 mm, W 1.9 mm; P small, 1.1 whorls; nucleus weakly inclined, DN 0.11–0.14 mm; P/T boundary weak; T with numerous sigmoid axial lirae fading on later T whorls; relatively wide body whorl with three peripheral spiral ribs and five to seven basal spiral ribs; upper apertural retraction deep, upper projection strongly expanding forwards; basal columellar fold or tooth present; umbilicus narrow.

Distribution. Apart from the studied material, this species is known from Pleistocene deposits of Vanuatu (Ladd 1982).

Differentiation. This species is rather similar to S. trochiformis Poppe, Tagaro & Dekker, 2006, in having a strong tooth on the columella and an aperture with projections and retractions. However, S. trochiformis has a higher spire (H/W ratio of holotype Poppe et al., 2006: 1.10; H/W ratio of S. donaldi 1.02-1.07 (table 2)) and a less swollen body whorl. Seguenzia donaldi differs from S. cf. keikoae by its wider whorls. The keel in S. donaldi is stronger, its axial lirae are weaker, the protoconch less inclined, the base of the body whorl flatter and the umbilicus wider.