Pleurotomella coelorhaphe Dautzenberg & Fischer 1896

Pleurotomella coelorhaphe Dautzenberg & Fischer, 1896

(Figs. 42–43)

Pleurotoma coelorhaphe Dautzenberg & Fischer, 1896: 425, pl. 15, fig. 13.

Pleurotoma (Pleurotomella) coelorhaphe Dautzenberg & Fischer, 1896: Dautzenberg (1927: 41, pl. 3, fig. 9). Pleurotomella coeloraphe (Dautzenberg & Fischer, 1896): Bouchet & Warén (1980: 39, figs. 34, 99, 222, 223), misspelled for coelorhaphe.

Type material: In Museé Océanographique de Monaco.

Type locality: Azores, Princesse Alice (1895), sta. 46 (37º 42’ 40”N, 27º 27’ 30”W), 1385 m.

Material examined: 15429 [2] OP I # 49; 17068 [2] OP I # 47; 19179 [9] OP II # 49; 19180 [2] OP II # 59; 19181 [2] OP I # 59.

Description: Shell wide, white, up to 4.22 mm long. Protoconch with about 3.5 whorls. Protoconch conical. Protoconch 1 with spiral rows of tiny crosses. Protoconch 2 with diagonal cancellation on the lower 2/3 of the whorls and axial riblets crossed by very fine and faint spiral threads on the upper third. Clear-cut proto-teleoconch boundary. Teleoconch whorls with a slightly concave area below the suture, ornamented by axial riblets. Below this area the whorl is inflated and with 14 axial ribs (on the third whorl) that continue over the upper half of the base. About 21 sharp equidistant spiral cords distributed from the body whorl to the base. Spiral cords form projections where they cross the axial ribs. Shell surface granulose. Suture shallow. Base moderately elongated and concave. Anal sinus not discernible in our material. Outer lip thin. Anterior siphonal canal long and narrow. Aperture elliptical.

Geographic distribution: Northeast Atlantic: Azores (Dautzenberg & Fischer, 1896; Dautzenberg, 1927); Azores and Portugal (Bouchet & Warén, 1980). Southwest Atlantic: Campos Basin, Rio de Janeiro (this paper). Bathymetry: 722 m (this paper)– 1980 m (Bouchet & Warén, 1980).

Discussion: This species is very similar to P. packardii, the main difference being in the protoconch which is conical with a narrow tip, as in most other species of Pleurotomella or even Raphitomidae, rather than the unusual sub-cylindrical, blunt-tipped protoconch observed in P. packardii. Concerning the teleoconch, P. coelorhaphe shows a shell surface covered by sparse diminutive grains, while P. packardii has a similar grainy surface but more crowded and with a spiral organization. Besides, the spiral cords are of equal strength in P. coelorhaphe but unequal in P. packardii. From other species of Pleurotomella, it can be distinguished by the rapidly increasing whorls with a strongly convex middle portion, resembling a tangerine.

Pleurotomella coelorhaphe is reported for the first time in South Atlantic waters. It was previously known to occur in Azores and Portugal. Its bathymetric range is also increased. The shallowest depth previously reported was 1250 m (Bouchet & Warén, 1980) and it has now been found at 722 m.