Sinezona platyspira, 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 : 9-11

Sinezona platyspira new species

( Figure 7 )

Type material. Holotype ( NMNZ M.301400: Fig. 7 A). 0.95 × 0.6 mm. Paratype from type locality ( NMNZ M.301399, 1: Fig. 7 B).

Type locality. West Norfolk Ridge, W of Cape Reinga, New Zealand, 34.298˚S, 168.430˚E, 785–800 m, 2 June 2003, RV Tangaroa , comminuted coral and bryozoans.

Etymology. Platy-, flat, -spira, spire: referring to the flat spire of the species. Adjective.

Description. Shell small (to 0.95 mm. Fig. 7 ), trochiform depressed. Protoconch 1 whorl, strong axials, no apertural varix, apertural margin convex. Teleoconch I of 0.9–1.1 whorls, 12–26 axial lamellae, interstices with finest growth marks, no spirals. Teleoconch II of 0.6 whorl, suture deeply impressed. Shoulder flat; approximately 12–21 axial cords, often restricted to adsutural quarter, in some specimens almost absent; no spirals. Base with distinct constriction below selenizone; on teleoconch I, axial lamellae continuous into umbilicus; on teleoconch II, fewer axial lamellae (approximately 6) fading out towards umbilicus; no spirals. Umbilicus open, deep, cavity produced by rounded portion of previous whorls, underside of protoconch visible, bordered by strong spiral cord. Aperture tilted, D-shaped, roof overhanging. Selenizone above periphery, keels strong, quite elevated; lunules distinct, foramen closed with short anterior raphe.

Animal unknown.

Distribution. West Norfolk Ridge, W of Cape Reinga, northern New Zealand, 785– 800 m.

Specimen records. West Norfolk Ridge, W of Cape Reinga, 34.285˚S, 168.430˚E, 785–800 m (NMNZ M.172128, 31).

Remarks. Sinezona platyspira can be distinguished from New Zealand species as follows. Sinezona bandeli has a strong constriction on the base below the selenizone, has an umbilicus with straight walls, and the protoconch has an apertural varix. Sinezona brevis has an umbilicus with straight walls, a much shorter selenizone (0.1 vs. 0.4 whorl), and a more elevated spire. Sinezona iota has a much taller shell with protruding protoconch, the umbilicus has straight walls, and the protoconch has an apertural varix. Sinezona laqueus has a stronger constriction of the base below the selenizone, the umbilicus has straight walls, and has axial folds as opposed to lamellae. Sinezona levigata has a callus covering the umbilicus, lacks a constriction of the base below the umbilicus, and has no axial lamellae. Sinezona mechanica has an umbilicus with straight walls, about twice as many finer axial cords, and has axial cords over the entire width of the shoulder on teleoconch II. Sinezona pacifica has an umbilicus with straight walls, is overall taller, and has a protoconch with apertural varix. Sinezona pauperata lacks a selenizone, has a very narrow umbilicus, and lacks axial lamellae.

The subantarctic Sin. subantarctica has a callus covering the umbilicus, a very short selenizone (<0.1 whorl), and spiral threads on the lower base. Satondella minuta Bandel, 1998 from the Indo-Pacific has much more elevated keels bordering the foramen.

Figures

FIGURE 7. Sinezona platyspira new species. West Norfolk Ridge, W of Cape Reinga, 34.298 ˚ S, 168.430 ˚ E, 785 – 800 m A. Holotype. (NMNZ M. 301400). B. Paratype (NMNZ M. 301399). Scale bars shell = 0.5 mm. Scale bars protoconch = 100 µm.