Propilidium exiguum (Thompson, 1844)

Fig. 11 h–k

Patella ? ancyloides Forbes, 1840 (p. 108, pl. 2, fig. 16).

Patella exigua Thompson, 1844 (p. 259).

Propilidium ancyloïdes [sic] Forbes—Jeffreys 1883[a] (p. 673).

Propilidium ancyloide (Forbes) — Nordsieck 1968 (p. 16, pl. 3, fig. 08.20); Di Geronimo & Panetta 1973 (p. 74); Di Geronimo & Li Gioi 1980 (pl. 1, fig. 9); Di Geronimo & Bellagamba 1985 (pl. 2, fig. 7).

Propilidium ancyloide Forbes, 1849 — Ghisotti & Melone 1970 (p. 41, fig. 8.20 a–d).

Propilidium ancyloide (Forbes, 1840) — Fretter & Graham 1976 (p. 34, figs. 24–25); Smriglio et al. 1988 (p. 1, figs. 3a–e).

Propilidium ancyloides (Forbes, 1840) — Poppe & Goto 1991 (p. 72, pl. 5, fig. 15).

Propilidium exiguum (Thompson, 1844) — Dantart & Luque 1994 (p. 303, figs. 94–104); De Frias Martins et al. 2009 (p. 22, fig. 4).

Propilidium exiguum (Thompson, 1843) — Giannuzzi-Savelli et al. 1994 (p. 34, fig. 31); Repetto et al. 2005 (p. 70, bottom right fig.); Portalatina 2008 (p. 149, figs. 2A–B).

Propilidium exiguum (Thompson W., 1844) — Beck et al. 2006 (p. 37, mid fig.).

Propilidium exiguum (W. Thompson, 1844) — Peñas et al. 2006 (figs. 9–10).

Diagnostic characters. Conical and rather elevated shell; oval basal outline; subcentral recurved apex; numerous, fine radial and concentric riblets forming small rounded nodules at the intersections. Protoconch: bilateral symmetrical; 1.25 whorls; diameter about 170 µm; densely packed granules over the first 0.8 whorls, then sparse; transition to the teleoconch abrupt.

Remarks. Propilidium ancyloide (Forbes, 1840) is currently regarded as a synonym of the present taxon (CLEMAM 2016); the name is a homonym of Patella ancyloide Sowerby, 1824 .

Occurrence. Box-corer samples BC11 (1 specimen), BC66 (2), BC68 (1), BC71 (2), BC72 (2); cores BC21 (1), BC67 (4), BC72 (1). Maximum length: 3 mm.

Distribution and habitat. The species ranges from Scandinavia to the Azores, the Canaries and the Mediterranean, dwelling on hard substrates (e.g. gravel, stones, millipores, coral and shell grit) mainly in the 7–600 m bathymetric interval and occasionally deeper. It occurs in gradually deeper water southward; it was reported as living in white coral biocoenoses (Di Geronimo & Panetta 1973; Fretter & Graham 1976; Poppe & Goto 1991; Dantart & Luque 1994; Høisaeter 2009); it was regarded as an accompanying element of VP (bathyal mud) biocoenosis (Di Geronimo & Bellagamba 1985).

Fossil record. Pliocene of Sicily; Pleistocene of central and southern Italy (Di Geronimo & Li Gioi 1980; Di Geronimo & Bellagamba 1985; Barrier et al. 1987; Di Geronimo et al. 2005).