Tornus subcarinatus (Montagu, 1803) (Fig. 9F 1-F 3)

Helix subcarinata Montagu, 1803: 438, pl. 7, fig. 9.

Tornus subcarinatus – Van Dingenen et al. 2016: 149, pl. 11, fig. 9, pl. 12, fig. 3. — Landau et al. 2018: 303, pl. 131, fig. 1.

For more, see synonymy list in Van Dingenen et al. (2016) and Landau et al. (2018).

MATERIAL AND DIMENSIONS. — Maximum height 0.8 mm, width 1.2 mm. — RGM.1364994 (19), leg. ACJ; RGM.1365009 (93), leg. AWJ; RGM.1365299 (1), leg. AWJ; RGM.1405531 (1), leg. ACJ .

SPECIES CHARACTERISATION. — Small, depressed, subcircular shell. Protoconch of 2.5 smooth whorls; three teleoconch whorls with carinate shoulder, mid-whorl and peribasal cords, sinuous ribs on dorsum and venter; base flattened, bearing two further elevated cords, the medial periumbilical cord delimiting wide, deep umbilicus with ribs extending within; aperture wide, rounded, strongly oblique in profile.

DISTRIBUTION. — Middle Miocene: Atlantic, Loire Basin, France (Glibert 1949). — Upper Miocene: Atlantic, NW France (Landau et al. 2018). — Lower Pliocene: NSB, Coralline Crag, England (Wood 1848; Harmer 1923; Atlantic, NW France (Van Dingenen et al. 2016); central Mediterranean, Italy (Chirli 2006). — Upper Pliocene: NSB, Red Crag, England (Wood 1848; Harmer 1923). — Upper Pliocene-Pleistocene: Atlantic, NW France (Cossmann 1918; Brébion 1964). — Lower Pleistocene: Atlantic, Selsoif, NW France (this paper). — Upper Pleistocene: NSB, The Netherlands (Van Regteren Altena et al. 1954); Atlantic, British Isles (Harmer 1923). Today this species is present in the Atlantic coasts of Europe from British Isles to Tarifa (Fretter & Graham 1978).

REMARK

Van Dingenen et al. (2016:149) highlighted the problem with the Tornus subcarinatus (Montagu, 1803) species concept as accepted at present, in which specimens with paucispiral and multispiral protoconchs are considered conspecific. They concluded that there were two species: an Atlantic species T. subcarinatus, with a multispiral protoconch of about 2.1- 2.25 whorls, with a small nucleus (counting including first half whorl: Rolán & Rubio 2002: figs 5, 6; Van Aartsen et al. 1998: fig. 7), and a Mediterranean species that is at present unnamed with a paucispiral protoconch of 1.25-1.4 whorls, with a larger nucleus (Rolán & Rubio 2002: figs 13, 14; Van Aartsen et al. 1998: fig. 7). With a protoconch of 2.5 whorls the specimens from Selsoif are typical of the Atlantic species T. subcarinatus .