Spirolaxis centrifugus (Monterosato, 1890)

Fig. 16 o–q

Pseudomalaxis centrifuga Monterosato, 1890 (p. 161).

Pseudomalaxis (Spirolaxis) centrifuga (Monterosato)—Monterosato 1913 (p. 363, lower fig. in same page); Nordsieck 1968 (p. 64, pl. 10, fig. 37.30); Taviani 1984 (p. 42, pl. 2, figs. 4–5).

Pseudomalaxis (Spirolaxis) centrifuga (Monterosato, 1913) — Nordsieck 1972 (p. 147, pl. R XIV, fig. 10).

Spirolaxis centrifuga — Boss & Merrill 1984 (p. 362, pl. 62, fig. 2).

Spirolaxis centrifugus (Monterosato, 1890) —Melone & Taviani 1984 (p. 185, figs. 62–64).

? Spirolaxis clenchi Jaume & Borro, 1946 —Melone & Taviani 1984 (p. 188, figs. 65–67); Repetto et al. 2005 (p. 226, top right fig.).

Diagnostic characters. Planispiral shell; disjuncted first teleoconch whorl; subquadrangular aperture; four robust spiral keels placed at angles of the quadrangular whorls; thin sinuous axials forming elongated nodes on keels. Protoconch: slightly more than 2 whorls; diameter about 500 µm; surface smooth; transition to the teleoconch marked by a simple lip preceded by a narrow, slightly sinuous varix.

Remarks. The western Atlantic species S. exquisitus (Dall & Simpson, 1901) is sometimes considered a synonym of S. centrifugus (cf. Melone & Taviani 1984). The Caribbean Spirolaxis clenchi Jaume & Borro, 1946 could also be a synonym of S. centrifugus, but the relationships between the two taxa are unclear.

Occurrence. Box-corer sample BC72 (1 specimen). Diameter: 3.5 mm.

Distribution and habitat. The species is distributed on both sides of the Atlantic and in the Mediterranean, ranging in depth from circalittoral to bathyal zones (Melone & Taviani 1984).

Fossil record. Pliocene? of Italy (Tabanelli 2008, as S. clenchi).