Stenostylus perturbatus, Breure, Abraham S. H., 2011

Breure, Abraham S. H., 2011, Annotated type catalogue of the Orthalicoidea (Mollusca, Gastropoda) in the Royal Belgian Institute of Sciences, Brussels, with descriptions of two new species, ZooKeys 101, pp. 1-50 : 26

Stenostylus perturbatus sp. n. Figs 17 A–B

Diagnosis.

A large species of Stenostylus , with a very elongated spire, a roughly sculptured surface, and the aperture relatively small, and narrow, compared to other species of the genus.

Description.

Shell 56.5 mm, 2.0 times as long as wide, elongate, with straight sides, imperforate; rather thin. Colour dark-brown to blackish, with axially oriented, yellowish lines, varying from small to somewhat broader, in some places forming patches, but always irregular, never from suture to suture; upper whorls light-brown, the first ones denuded of the periostracum. Surface rather shining, with thickened growth striae where the colour is yellowish; some traces of spiral impressions, especially visible at the upper side of the last whorl. Protoconch eroded. Whorls 6.2, slight convex, the last 0.75 total shell height; suture well impressed. Aperture elongate-ovate, 0.45 times shell height, 1.49 times as long as wide, somewhat shining inside, whitish. Peristome thin, hardly expanded; columellar margin thin, curved, transitioning into the parietal wall, which has a very thin, whitish callus.

Dimensions.

Holotype H 56.5, D 27.7, HA 25.5, WA 17.1.

Type locality.

Peru, Dept. Pasco, Huancabamba.

Type material.

RBINS/MT698, holotype (ex Preston).

Comparisons with other taxa.

This new species is placed in Stenostylus , despite its protoconch sculpture being unknown, on account of its general shape, the thickened growth striae, and the traces of a pearly lustre inside the aperture (cf. Breure 2008: 248). It resembles Stenostylus zilchi Weyrauch, 1956, which occurs on the western side of the Cordillera in Dept. Lima, and which differs from Stenostylus perturbatus by (1) being smaller; (2) having the last whorl more inflated; (3) having a wider aperture.

Remarks.

The single specimen known was found under the same manuscript name of Preston, from whom Dautzenberg obtained the shell on 30.xii.1909. The lip is damaged, especially at the columellar and basal side, and has partly been broken off.

Etymology.

(L.), perturbatus, unquiet; referring to the distinctive colour pattern of the shell. The epithet is used as an adjective.