Sinezona wanganellica, 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 : 11-13

Sinezona wanganellica new species

( Figures 8–9 )

Type material. Holotype ( NMNZ M.303304: Fig. 8 ). 0.71 × 0.41 mm. Paratypes from type locality ( NMNZ M.178433, 7). Wanganella Bank summit, West Norfolk Ridge, 32.606°S, 167.584°E, 120–126 m ( NMNZ M.171826, 14: Fig. 9 B–C). Wanganella Bank summit, 32.573°S, 167.517°E, 113 m ( NMNZ M.174832, 14: Fig. 9 A).

Type locality. Wanganella Bank summit, West Norfolk Ridge, NW of Cape Maria van Diemen, New Zealand, 32.543°S, 167.487°E, 133 m, rhodolith gravel and red algae.

Etymology. Named for the type locality; adjective.

Description. Shell small (to 0.7 mm. Figs 8–9 ), trochiform depressed. Protoconch of 1 whorl, 19–21 sharp axials from midline to outer suture, embryonic cap with some irregular flocculations, no apertural varix, apertural margin slightly convex. Teleoconch I of 0.875–0.9 whorl with 12–22 sharp to elevated axial cords with onset close to suture on early teleoconch I shifting to past position of selenizone with onset of selenizone; interstices with finest growth marks, no spiral sculpture. Teleoconch II of 0.66 whorl, suture impressed. Shoulder overall flat, concave towards selenizone; mainly finest growth marks, 0–12 axial cords in adsutural quarter, no spiral sculpture. Base with distinct constriction below selenizone, same density and strength of axial cords as on teleoconch I; some axial cords not reaching umbilicus. Umbilicus formed by rounded portion of previous whorls, underside of protoconch visible. Selenizone above periphery; keels moderately strong, quite elevated; lunules very strong; slit closed anteriorly to foramen. Aperture rounded D-shaped, roof overhanging. Animal unknown.

Distribution. West Norfolk Ridge, 113– 800 m.

Specimen records. West Norfolk Ridge. 32.653˚S, 167.528˚E, 133 m (NMNZ M.174834, 1); 32.666˚S, 167.560˚E, 133 m (NMNZ M.174841, 5). ESE of Wanganella Bank , 34.284˚S, 168.430˚E, 785–800 m (NMNZ M.172128, 31).

Remarks. Sinezona wanganellica can be distinguished from New Zealand species as follows. Sinezona bandeli Marshall, 2002 has an overall taller shell, has spiral threads on the shoulder and base of the teleoconch, and has a narrower umbilicus occluding the underside of the protoconch. Sinezona mechanica lacks a sunken in apex, has a more rounded whorl profile, and has at least 50% more axial cords. Sinezona platyspira has a longer teleococh I (1.125 vs. 0.875 whorl) and has at least 50% more axials on the protoconch. Scissurella regalis has a protoconch with at least 50% more axials, which bear strong median thickenings, has a longer teleoconch (1.125 vs. 0.875 whorls), and retains an open slit.

Figures

FIGURE 8. Sinezona wanganellica new species. Holotype. Wanganella Bank summit, West Norfolk Ridge, 133 m (NMNZ M. 303304). Scale bar shell = 0.5 mm. Scale bar protoconch = 100 µm.

FIGURE 9. Sinezona wanganellica new species. Paratypes. A. Wanganella Bank summit, West Norfolk Ridge, 113 m (NMNZ M. 174832). B – C. Wanganella Bank summit, 120 – 126 m (NMNZ M. 171826). Scale bars shell = 0.5 mm. Scale bars protoconch = 100 µm.