Calliostoma undetermined

Calliostoma sp.

Fig. 4A–C

ITALY – Tuscany • 1 spec.; Le Colline; MSF 1207 (H = 10 mm).

Conical shell, about 10 mm high, at least seven straight-sided whorls beaded spiral cords at upper and lower suture, smooth in between; basal margin sharp, base smooth, almost flat; aperture subcircular, entire.

Sacco (1896) illustrated various species of Calliostoma (as Ampullotrochus) from Miocene and Pliocene strata of northern Italy. Similar regarding the nodular subsutural cords are Ampullotrochus cinculatus (Verrill, 1884) (Sacco 1896: 45, pl. 4 fig. 46) and A. granulatus Born, 1778 (Sacco 1896: 42–43, pl. 4 figs 34–37). The latter species has, as the name indicates, a more granular sculpture (see Gardella & Tabanelli 2017: figs 3–4). A similar fossil Calliostoma with smooth whorl flanks but less distinct subsutural nodular cords is Calliostoma margarita Lozano-Francisco & Vera-Peláez, 2002 from the Pliocene of southern Spain and northern Italy (Lozano-Francisco & Vera-Peláez 2002; Gardella & Tabanelli 2017). Similarly high-spired but with more distinct spiral ornament is the Pliocene Ampullotrochus perstriolatus Sacco, re-illustrated by Ferrero Mortara et al. (1984: pl. 49 fig. 5).

Middle Miocene (lower Serravallian), northern Italy.