Discotectonica discus ( Philippi, 1844 )

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 : 71

Discotectonica discus ( Philippi, 1844)

Fig. 16 d–f

Solarium discus Philippi, 1844 (p. 225, pl. 28, fig. 12).

Solarium discus, Ph. — Monterosato 1873 (p. 4, figs. 1–4).

Solarium discus Philippi—Hidalgo 1917 (p. 644).

Philippia pseudoperspectiva (Brocchi) — Nordsieck 1968 (p. 64, pl. 10, fig. 37.40).

Discotectonica discus ( Philippi, 1844) —Melone & Taviani 1984 (p. 152, figs. 1–10); Repetto et al. 2005 (p. 224, bottom left fig.); Peñas et al. 2006 (p. 128, figs. 282–284); Mastrototaro et al. 2010 (fig. 5 b).

Diagnostic characters. Low conical, almost discoidal shell; very low spire; rounded aperture with weak adaxial and abaxial angulation; deep and wide umbilicus bordered by 2 rows of elongated knobs; robust peripheral keel; spiral rows of squarish nodes ceasing on the mid-base; dense axial striation on base. Protoconch: heterostrophic; about 2 whorls, the first immersed; diameter about 680 µm; surface smooth; transition to the teleoconch marked by a thread-like varix.

Occurrence. Box-corer samples BC67 (2 specimens), BC70 (1), BC71 (2), BC72 (17). Maximum diameter: 6.5 mm.

Distribution and habitat. Discotectonica discus is distributed from the Lusitanic province to West Africa and the Mediterranean, as well as in the Caribbean area; it is a rare species dwelling on circalittoral to bathyal mud (Melone & Taviani 1984; Poppe & Goto 1991). In the Santa Maria di Leuca CWC biotope, it was found on living colonies of Madrepora oculata (Mastrototaro et al. 2010) .

Fossil record. Pleistocene of Ischia, southern Italy (Melone & Taviani 1984).

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).