Scissurella regalis, 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 : 2-4

Scissurella regalis new species

( Figure 1 )

Type material. Holotype ( NMNZ M.173745: Fig. 1 A). Paratypes from type locality ( NMNZ M.303322, 12: Fig. 1 B). 1.16 × 0.76 mm.

Type locality. Three Kings Rise, New Zealand, 31.866˚S, 172.433˚E, 780–790 m, RV Rapuhia, 5 Feb. 1988, comminuted bryozoans and shell.

Etymology. Regalis , Latin for royal in reference to the type locality.

Description. Shell small (to 1.16 mm: holotype. Fig. 1 A), trochiform, depressed. Protoconch of 1 whorl, fine axials with strong median thickenings, no apertural varix, apertural margin straight. Teleoconch I of 1.125 whorls, 23–27 axial lamellae, no spiral sculpture. Teleoconch II of 0.66 whorl, suture strongly impressed. Shoulder with axial lamellae of increasing density (holotype), interstices with fine growth lines, no spiral sculpture. Base with slight constriction below selenizone, same strength and density of axial lamellae as on shoulder, indistinct spiral threads on last quarter whorl from below selenizone, growing fainter towards umbilicus. Umbilicus wide, rounded whorls, underside of protoconch visible. Selenizone above periphery, keels moderately strong, moderately elevated; slit open, margins parallel. Animal unknown.

Distribution. Three King Rise, 780– 790 m.

Remarks. This species is only known from the type lots. Scissurella regalis is strikingly similar to Sinezona platyspira n. sp., but the slit has parallel rather than convergent margins and the axial lamellae extend almost to the selenizone rim on the last half whorl. The crowding of the axial lamellae towards the apertural margin in the holotype indicates that it is a fully-grown specimen and not a juvenile of a Sinezona species, in which the foramen has yet to close. A comparable Scissurella-Sinezona pair is Scissurella azorensis Nolt, 2008 and Sinezona semicostata Burnay & Rolán, 1990 , from the Macaronesian Islands. Small specimens of Sci. regalis and Sin. platyspira may be indistinguishable based on shell morphology.

Scissurella prendrevillei Powell, 1933 (DLG [pers. obs.] suspects that Sci. marshalli Bandel, 1998 is a synonym) from New Zealand has a protoconch with fine axials but has less distinct median thickenings, has fewer axial lamellae on teleoconch I (17–20 vs. 23–27), and usually has broad but low spiral cords surrounding the umbilicus. Scissurella azorensis from the Azores and the Western Mediterranean and Sci. maraisorum Geiger, 2006 from eastern South Africa have broader and lower axial cords, which do not reach the suture, and have no spiral sculpture on shoulder or base. The Panamic Scissurella kaiserae Geiger, 2006 has a shorter teleoconch I (<1 vs.> 1 whorl), lacks spiral sculpture on the shoulder, and the axial cords are at most as tall as wide. Scissurella lobini (Burnay & Rolán, 1990) from the northeastern Atlantic has a protoconch with more widely spaced axial cords devoid of a median thickening, lacks spiral sculpture on the teleoconch, and has at least 50% fewer axial cords.

Figures

FIGURE 1. Scissurella regalis new species. Three King Rise, New Zealand, 780 – 790 m. A. Holotype (NMNZ M. 173745). B. Paratype (NMNZ M. 303322). Scale bars shell = 1 mm. Scale bars protoconch = 100 µm.