Sinezona mechanica Geiger & Marshall, 2012, new species

• Main Authors: Geiger, Daniel L., Marshall, Bruce A.
• Format: Other/Unknown Material
• Language: unknown
• Published: 2012
• Subjects: Biodiversity; Taxonomy; Animalia; Mollusca; Gastropoda; Lepetellida; Scissurellidae; Sinezona; Sinezona mechanica; New Zealand; Saunders; Geiger; Saunders Canyon; Macquarie Island
• Online Access: https://zenodo.org/record/6166674; https://doi.org/10.5281/zenodo.6166674

Sinezona mechanica new species (Figures 4–6) Type material. Holotype (NMNZ M. 174828: Fig. 4). 1.28 × 0.88 mm. Paratypes from type locality (NMNZ M.045402, 2: Fig. 5 A–B). Additional paratypes: Saunders Canyon, off Otago Peninsula, South Island, New Zealand, 45.767 ˚S, 170.900 ˚E, 360 m (NMNZ M. 160300, 2: Fig. 5 C); Aerial Cove, Macquarie Island, 54.483 ˚S, 158.950 ˚E (AMS C.404496, 20). Type locality. Ocean Bay, Chatham Island, New Zealand, 43.833 ˚S, 176.783 ˚W, 12–15 m, 7 Dec. 2000, F.J. Brook, bryozoans, shell and sand from rock crevice. Etymology. Latin adjective referring to the sculpture of shell and protoconch suggestive of mechanical gears. Description. Shell small (to 0.89 mm. Figs 4–5), depressed trochiform globular. Protoconch of 1 whorl, many dense axial cords on centrifugal portion of whorls, thickened at top forming (near) continuous connecting spiral cord. Apertural varix terminal (Fig. 8 B), not connected to embryonic cap, apertural margin straight. Teleoconch I of 0.9–1 whorl, approximately 17–20 strong (occasionally barely perceptible) axial cords, no spirals. Teleoconch II of 0.6 whorl, suture little impressed. Shoulder slightly concave, same density and strength of axial cords as on teleoconch I, finest growth marks in interstices, no spirals. Base with weak constriction below selenizone, rounded, same density and strength of axial cords as on shoulder; approximately 4 weak, granular spiral cordlets in adumbilical 1 / 5 of base. Umbilicus of moderate width, at sharp angle to base, bordered by weak to moderate strength spiral cord, wall straight, smooth. Aperture rounded, roof overhanging. Selenizone above periphery; keels low, moderate strength; lunules distinct; slit open, margins somewhat converging. Radula (Fig. 6). Rachidian trapezoid, central cusp largest, three cusps on each side. Lateral teeth 1–3 similar, apical cusps largest, 4–6 on outer cutting edge. Lateral tooth 4 reduced, hook shaped, with 1 minute point on each side of tip. Lateral tooth 5 enlarged by broadening, apical cusp ...