Satondella bicristata, Geiger, Daniel L. & Marshall, Bruce A., 2012

Geiger, Daniel L. & Marshall, Bruce A., 2012, New species of Scissurellidae, Anatomidae, and Larocheidae (Mollusca: Gastropoda: Vetigastropoda) from New Zealand and beyond, Zootaxa 3344, pp. 1-33 : 15

Satondella bicristata new species

(Figure 12)

Type material. Holotype ( NMNZ M.137457: Fig. 12C). 0.66 × 0.37 mm. Paratypes from type locality ( NMNZ M.301393, 2: Fig. 12A–B).

Type locality. Seamount 130 km S of Esperance Rock, Kermadec Ridge, NE of New Zealand, 538 m, 32.472˚S, 179.265˚W, 15 Apr. 1997, FV Santa Maria, hardground, foraminiferal sand, sponges and bryozoans.

Etymology. Bi-, Latin for two; -cristata, Latin for crest-bearing, referring to the two elevated ridges formed on shoulder and base by the axial lamellae.

Description. Shell small (to 0.67 mm. Fig. 12), depressed trochiform, almost planispiral. Protoconch sunken in, 1 whorl, fine axials from highest point centrifugally to suture, no apertural varix, apertural margin sinusoid. Teleoconch I of 1.25–1.5 whorls; approximately 32–36 axials, near suture and peripherally as axial cords, in position of selenizone and on mid-base as raised lamellae; spiral cordlet in position of selenizone and on mid-base, crossing with tallest portion of axial lamellae; occasionally some additional spiral threads. Teleoconch II of 0.125 whorl, suture deeply impressed. Shoulder convex, same sculpture as on teleoconch I. Base with distinct constriction below foramen, sculpture as on teleoconch I. Umbilicus open, underside of protoconch visible, towards base bordered by strong bulge, no distinct wall. Aperture rounded D-shaped. Selenizone absent, foramen above periphery, anteriorly closed by raphe; keels strongly elevated, moderately strong.

Animal unknown.

Distribution. Kermadec Ridge, New Zealand. 538 m.

Remarks. The generic placement is suggested by the high elevation of the keels of the foramen.

Satondella minuta from the Indo-Malayan Archipelago has less depressed shell, fewer axial lamellae, and a distinct selenizone. Satondella azonata from New Zealand has about half as many raised axial lamellae and lacks spirals on the base. Scissurella condita Laws, 1939 from the Miocene of New Zealand has a similar overall shell shape, but has a distinct selenizone and an open slit. All other Satondella species are markedly more elevated.