Type material. Holotype, MNRJ 18.306 (Fig. 1).
Type locality and distribution. continental slope of the state of Alagoas (northeastern Brazil), 'Natureza', 10 °06' 35 '' S, 35 ° 46 ' 41 '' W, 720 m, 16.xii. 2001.
Description. Shell whitish, small (3.4 mm long), strong, thick, conical. Protoconch with about 2 moderately convex whorls, sculptured with microscopic pits. Spire moderately high. Suture rather deep. Teleoconch with about 6 constricted whorls; whorls strongly convex, irregular in outline; surface covered by intritacalx densely sculptured with microscopic pits in square pattern. Axial sculpture with strong, moderately thick, rather high, rounded, prosocline, widely spaced ribs that do not form crenulations in subsutural region. Last whorl sculptured with 10 to 14 axial ribs, faint on basal ridge, weakly invading basal disc. Base delimited by slight ridge (resembling a keel). Basal disc strongly flattened, large, sculptured with microscopic pits, very weak axial ribs and prominent spiral rib at periphery of inner lip; intersection of axial and spiral rib(s) forming slight nodules. Aperture rounded; peristome thickened, double. Outer lip thickened by projection of axial rib. Umbilicus becoming very narrow, chinked.
Etymology. In homage to Dr. Alexandre D. Pimenta (MNRJ) for his initiative in reviewing the epitoniids and nystiellids of the Brazilian coast.
Remarks. Gregorioiscala pimentai n. sp. resembles G. annectens (Powell, 1951) described from the Falkland Islands in having a similar shell shape, teleoconch whorls with an irregular outline and a well-developed basal ridge. The new species differs clearly from G. annectens in having prominent axial ribs on all teleoconch whorls, a slight basal ridge and basal disc ornamented with pits and ribs. Powell (1951: 115, pl. 7, fig. 23) and Weil et al. (1999: 24, fig. 53) characterized G. annectens by the presence of obsolete axial ribs, mainly on the last teleoconch whorls, and a strong basal ridge. Furthermore, basal disc of G. annectens is not sculptured with spiral or axial ribs, as observed in G. pimentai n. sp.
The irregular outline of the teleoconch whorls and strong, widely spaced axial ribs of Gregorioiscala pimentai n. sp. are similar to those found on G. pachya (Locard, 1897) from southwest Europe and the Azores. However, the shell of G. pimentai n. sp. has a conical shape that is clearly smaller in total length, a smaller number of teleoconch whorls (about 6) and axial ribs with equal strength on all teleoconch whorls in comparison to G. pachya. Bouchet & Warén (1986: 544–545, figs. 1254–1255) and Weil et al. (1999: 42, fig. 113) characterized G. pachya as having a total length reaching about 33 mm, a very solid, heavy teleoconch sculptured with broad axial ribs that are sometimes thickened into varices. Furthermore, G. pimentai n. sp. has a straight columellar axis and thickened peristome, while G. pachya has a curved columellar axis and very thickened peristome, mainly on the region of the outer lip.