Pleurotomella cala ( Watson, 1886 )

Figueira, Raquel Medeiros Andrade & Absalão, Ricardo Silva, 2012, Deep-water Raphitomidae (Mollusca, Gastropoda, Conoidea) from the Campos Basin, southeast Brazil, Zootaxa 3527, pp. 1-27 : 20-22

Pleurotomella cala ( Watson, 1886)

( Figs. 38–40 )

Clathurella cala Watson, 1886: 361 , pl. XXVI, fig. 11;

Pleurotomella cala ( Watson, 1886) : Rios (2009: 349, species 904).

Type material: Syntypes BMNH 1887.2.9.113–114

Type locality: South-east Atlantic, Sta. 335, 32° 24’S 15°05’W, 2606 m.

Material examined: Type material and 18980 [1] OP I # 48; 17596 [1] OP I # 68; 18981 [1] OP II # 58; 18982 [1] OP II # 63; 18983 [1] OP II # 77; 16484 [1] OP I # 9; 16710 [1] OP II # 6.

Description: Shell wide, white, up to 8.28 mm long. Protoconch with about 2.5 whorls. Protoconch subcylindrical. Protoconch 1 flattened, with spiral rows of tiny crosses. Protoconch 2 with dominant curved axial ribs crossed by spiral threads on the upper half of the whorls, and diagonal cancellation on the lower half. Clear-cut proto-teleoconch boundary. Teleoconch whorls with a slightly concave area below the suture ornamented with slightly curved axial riblets and a fine spiral cord. Below this area the whorl is strongly convex and sculptured by about 14 prominent axial ribs (on the third whorl) that continue over the upper part of the base. Sharp equidistant spiral cords present over the convex part of the whorl, intercalating one stronger, one weaker, producing acute projections where they cross the axial ribs. About 33 spiral cords from the body whorl to the base. On the base, spiral cords are equal in strength and closer to each other than at the body whorl. Shell surface covered by weakly spirally organized granules. Suture shallow. Base medium-sized and concave. Anal sinus deep. Outer lip thin. Anterior siphonal canal relatively long and wide. Aperture ovate.

Geographic distribution: Southeast Atlantic: ( Watson, 1886); Southwest Atlantic: Rio Grande do Sul, Brazil ( Rios, 2009); Campos Basin, Rio de Janeiro (this paper). Bathymetry: 176 m ( Rios, 2009)– 2606 m ( Watson, 1886).

Discussion: This species can be distinguished from most of the others in the genus by the flattened subcylindrical protoconch. The only other species with this kind of protoconch is P. packardii ( Fig. 41 ). Bouchet & Warén (1980) distinguished these species by the protoconch, which they stated is blunter in P. packardii . We were unable to recognize this difference. We noticed however that P. packardii has much smoother whorls, its axial ribs do not form the acute nodules observed in P. cala ( Fig. 40 ). Our material is identical to the type of P. cala .

Pleurotomella cala was reported in Brazil for Rio Grande do Sul State (30ºS). Its distribution is here expanded further to include Rio de Janeiro (21–22ºS).

Figures

FIGURES 38 – 46. 38, 39, 40 — Pleurotomella cala (Watson, 1885); 38 — IBUFRJ 18982, 6.80 mm, whole shell; 39 — IBUFRJ 18982, protoconch, 40 — Syntype BMNH 1887.2.9.113 - 14. Figure 41 — Pleurotomella packardii Verrill, 1872, Syntype USNM 37874. Figures 42, 43 — Pleurotomella coelorhaphe Dautzenberg & Fischer, 1896, IBUFRJ 19181; 42 — 4.22 mm, whole shell; 43 — protoconch. Figures 44, 45, 46 — Pleurotomella perpauxilla (Watson, 1881); 44 — IBUFRJ 15428, 3.46 mm, whole shell; 45 — IBUFRJ 15428, protoconch; 46 — Syntype BMNH 1887.2. 9.1109. Scale bars: 38 = 1 mm; 39, 43 and 45 = 250 μm; 40 and 41 = 2 mm; 42, 44 and 46 = 500 μm.