“PLEUROTOMELLA ENDERBYENSIS n.sp. Pl. II., Fig. 8
Shell small, white, fusiform, elaborately sculptured and with a massive peripheral and a subsutural keel. Whorls 6, including a smooth protoconch of 2½ whorls, terminating in a thin raised varix. Spire-whorls with two or three thin, sharply raised spiral threads over the upper half of the shoulder and these are crossed by thin, sharp concavely arcuate lamellae. Below this, the surface, including the keels, is crowded with spiral lines of varying size. Four to six of the spirals fall upon the peripheral carina and two stronger spiral cords are situated between the peripheral carina and the suture. The peripheral and subsutural keels bear nine laterally compressed nodules per whorl and when viewed from above present an octagonal appearance. Sinus deep, reversed “L”-shaped, subsutural.
Height 8.8 mm.; diameter 5.0 mm. (Holotype, unique.)
BANZARE LOCALITY: Station 41, off Enderby Land, 193 metres (one fresh shell).
This species is closely allied to Pleurotomella annulata Thiele, which, however, lacks axial sculptural development.
The above three species as well as Thesbia ohlini Strebel, 1905 and Pleurotomella anomalapex, Powell, 1951, form a compact southern group closely similar to Pleurotomella but with a paucispiral instead of a “sinusigerid” protoconch. Another Antarctic species Pleurotomella simillima Thiele, 1912, is apparently very similar to the above group of species but it does have a typical “sinusigerid” protoconch and is undoubtedly a Pleurotomella.
The Pleurotomella species with the paucispiral protoconch are best included in the typical genus until the nuclear characters in Turrids are better understood.
Dall (1889, pp. 119-126), for instance, accounts for the presence of two types of protoconch in the genus by a suggestion that the smooth shelly nucleus is an infilling of a horny “sinusigerid” envelope which has subsequently weathered away.”
(Powell, 1958: 203)
