Sinezona globosa, Geiger, Daniel L., 2006

Geiger, Daniel L., 2006, Eight new species of Scissurellidae and Anatomidae (Mollusca: Gastropoda: Vetigastropoda) from around the world, with discussion of two new senior synonyms, Zootaxa 1128, pp. 1-33 : 16

Sinezona globosa new species: Figure 11

Type material. Holotype ( MNHN). Paratype ( MNHN, 1). 415–420 m, Wallis Island, 13.350°S, 176.133°W.

Type locality. 310–315 m, Loyality Basin, New Caledonia, 21.533°S, 166.483°E.

Etymology. Globosa , Latin adjective, noting the overall globular shape of the shell.

Description. Shell large (to 3.1 mm), trochiform globular. Protoconch of 0.875 whorls, embryonic cap with flocculant sculpture, remainder smooth with 3–4 fine spiral threads, apertural varix connected to embryonic cap, apertural margin unknown. Teleoconch I of 1.66 whorls, approximately 46–50 distinct axial cords, run over equaly spaced spiral lines, first spiral after 0.33 whorls, 14 at beginning of selenizone, interstices with broad growth marks. Teleoconch II of 1.125 whorls. Shoulder quite convex, suture modrately impressed, axials of same density as on teleoconch I, forming small points at intersection with spiral lines. Base slightly constricted below selenizone, with same density and strength of axials, approximately 20 spiral lines, becoming stronger and more closely spaced towards umbilicus. Umbilicus narrow in small specimens (paratype), moderately wide in large specimens (holotype), bordered by last spiral line of base, walls straight, smooth. Selenizone above periphery, keels elevated but often eroded due to their fragility, growth marks distinct, slit closed to elongated foramen. Aperture suborbicular, lip inflated, roof overhanging. Animal unknown.

Differential diagnosis. Sinezona macleani new species from the Philippines is more depressed, less globular, has a protoconch with flocculant sculpture, lacks an apertural varix, has a sharp elevated keel bordering the umbilicus, and usually a projecting shelf in the basal adumbilical corner of the aperture. Sinezona plicata (Hedley, 1899) with broad tropical Pacific distribution is overall more depressed, has a smooth protoconch occasionally with fine spiral lines, and has strong, elevated lamellae on the teleconch.

Distribution. Only known from type material.

Remarks. The paratype is slightly immature evidenced by the hardly descending aperture on the last quarter whorl, while the holotype is a fully grown specimen. It appears that the closure of the foramen occurs early on.

Figures

FIGURE 11. Sinezona globosa new species. A. Holotype. 310 ­ 315 m, Loyality Basin, New Caledonia, 21.533 ° S, 166.483 ° E (MNHN). B. Paratype 415 ­ 420 m, Wallis Island, 13.350 ° S, 176.133 ° W (MNHN). Scale bar shell = 1 mm. Scale bar protoconch = 100 µm.