Pleurotomella gibbera Bouchet & Warén, 1980

Negri, Mauro Pietro & Corselli, Cesare, 2016, Bathyal Mollusca from the cold-water coral biotope of Santa Maria di Leuca (Apulian margin, southern Italy), Zootaxa 4186 (1), pp. 1-97 : 70

Pleurotomella gibbera Bouchet & Warén, 1980

Fig. 16 a–c

Pleurotomella gibbera (Jeffreys ms) Bouchet & Warén, 1980 (p. 41, figs. 93, 220).

Pleurotomella gibbera Bouchet & Warén, 1980 ex Jeffreys ms.— Repetto et al. 2005 (p. 215, mid left fig.) Pleurotomella gibbera Bouchet & Warén, 1980 — De Frias Martins et al. 2009 (p. 65, figs. 242–244).

Diagnostic characters. Fusiform shell; spire whorls angular; concave subsutural shelf; oval aperture; moderately long siphonal canal; deep U-shaped anal sinus; 10 rounded and rather prominent collabral ribs per whorl; thin spiral cords increasing in number by intercalation during growth; blunt nodes at the intersections of ribs and cords. Protoconch: broadly conical; 5.5 whorls; diameter about 790 µm (protoconch I: 190 µm); height about 990 µm; first 1.5 whorls (protoconch I) with spirally connected T-shaped granules forming a square reticulated pattern; subsequent whorls (protoconch II) with sinuous collabral axial riblets and non-collabral prosocline riblets; the latter riblets absent in the adapical fourth, where only collabral riblets are present; spiral angulation on the last quarter whorl, with 2 additional spirals just before end of larval shell; transition to the teleoconch at deep sinusigera.

Occurrence. Box-corer samples BC66 (1 specimen), BC72 (2); cores BC04 (1), BC21 (2), BC67 (1), BC72 (1). Maximum height: 4 mm.

Distribution and habitat. Pleurotomella gibbera seems to have a restricted distribution from the Ibero- Moroccan Gulf and northwestern African waters to the western and central Mediterranean; it dwells on soft substrates in the 72–720 m depth interval ( Bouchet & Warén 1980; Bouchet & Taviani 1992; de Frias Martins et al. 2009).

Fossil record. None recorded.

Figures

FIGURE 16. a – c: Pleurotomella gibbera Bouchet & Warén, 1980, sample BC 66, scale bars: 1 mm (a), 0.2 mm (b – c, protoconch); d – f: Discotectonica discus (Philippi, 1844), sample BC 72, scale bars: 2 mm (d – e), 0.2 mm (f, protoconch); g – h: Pseudomalaxis zanclaeus (Philippi, 1844), sample BC 72, scale bar 5 mm; i – k: Solatisonax alleryi (Seguenza, 1876), sample BC 72, scale bars: 2 mm (i – j), 0.2 mm (k, protoconch); l – n: Solatisonax bannocki (Melone & Taviani, 1980), sample BC 71, scale bars: 2 mm (l – m), 0.2 mm (n, protoconch); o – q: Spirolaxis centrifugus (Monterosato, 1890), sample BC 72, scale bars: 1 mm (o – p), 0.2 mm (q, protoconch).