Seguenzia triteia, Salvador, Rodrigo B., Cavallari, Daniel C. & Simone, Luiz R. L., 2014

Salvador, Rodrigo B., Cavallari, Daniel C. & Simone, Luiz R. L., 2014, Seguenziidae (Gastropoda: Vetigastropoda) from SE Brazil collected by the Marion Dufresne (MD 55) expedition, Zootaxa 3878 (6), pp. 536-550 : 548

Seguenzia triteia sp. nov.

( Figs. 25–28 )

Type material: Holotype: MNHN IM- 2000-27536. Paratypes: MNHN IM- 2000-27540, 8 shells + fragments, MZSP 116280, 3 shells, from: BRAZIL: Espírito Santo: off São Mateus, continental slope of Abrolhos, 18°59’S 37°47’W, 1540–1550 m (MD55, sta. DC70, 26/v/1987).

Type locality: Brazil: Espírito Santo: off São Mateus, continental slope of Abrolhos, 19°01’S 37°47’W, 1500–1575 m (MD55, sta. CB79, 28/v/1987).

Distribution: Southeastern Brazil, off Espírito Santo state.

Etymology: The specific epithet is in apposition, and is derived from Greek mythology. Triteia , daughter of Triton, was a haliad (sea nymph) priestess of Athena, from the town of Triteia in Achaea, Greece; her son with the war god Ares, named Melanippos, gave his mother’s name to the city.

Diagnosis: Spire narrow. Teleoconch sculptured by numerous spiral cords with very strong axial ribs between them; whorl base with same sculpture pattern.

Description: Shell small (height 3.3 mm), conical (1.5 taller than wide), relatively thick-walled; spire tall, prominent, height 2/3 of shell height, spire angle 60°; color nacreous glossy white. Protoconch (~1 whorl, 0.3 mm) prominent, bulbous, with pitted, irregular surface; protoconch-teleoconch transition well-marked as a distinct change in sculpture. Teleoconch of 6½ whorls, with inconspicuous suture; sculpture consisting of very strong spiral cords crossed by widely-spaced strong axial ribs, with very fine spiral threads between cords; spire whorls bearing 2–3 conspicuous spiral cords, a stronger, median one that forms a well-marked carina; axial ribs prosocline above spiral cord and orthocline (on first teleoconch whorls) to opistocline below it. Whorl base sculpture similar, with spiral cords decreasing in strength and becoming more narrowly spaced towards umbilical region. Whorls concave between cords, but with overall convex whorl profile somewhat angulated at second spiral cord. Aperture roundedtrapezoid, height 1.4 of shell height, roughly as high as wide, with a columellar tooth and three labral sinuses: a very deep subsutural sinus and two adjacent and shallower sinuses, one on lowermost portion of columellar region of aperture and the other on peripheral part of basal region. Umbilicus imperforate.

Measurements (in mm): Holotype: 7½ whorls, H = 3.3; D = 2.4; h = 1.2; d = 1.0. Paratypes: MZSP 116280, 7½–7.7 whorls, H = 2.9 ± 0.5; D = 2.2 ± 0.2; h = 0.9 ± 0.1; d = 0.9 ± 0.2.

Material examined: Types.

Remarks: The present specimens, despite having the overall shell morphology of Seguenzia , can be easily distinguished from all its congeners by its marked teleoconch sculpture, with conspicuous spiral cords and very strong axial sculpture. The other diagnostic features of Seguenzia triteia sp. nov. include a narrower spire and having on the whorl’s basal region the same kind of sculpture as the remainder of the teleoconch. The single most similar species to S. triteia is S. levii Marshall, 1991 from New Caledonia, which also bears a very strong teleoconch sculpture; nevertheless, S. triteia can be easily distinguished from this species by its smaller size and its more regular and delicate teleoconch sculpture.

Figures

FIGURES 25 – 28. Seguenzia triteia sp. nov.; 25. Holotype MNHN IM- 2000 - 27536, apertural view (H = 3.3 mm, D = 2.4 mm); 26 – 28. Paratype MNHN IM- 2000 - 27540 (H = 3.1 mm, D = 2.2 mm); 26. Lateral view under SEM; 27. Protoconch detail under SEM (scalme bar = 0.1 mm); 28. Umbilical view under SEM.