Lucilla subteres (Clessin, 1877)

(Fig. 24)

Helix (Patula) subteres Clessin, 1877: 35 .

Patula subteres: Clessin, 1885: 76 (pl. 7, fig. 6).

Pyramidula subteres: Wenz, 1923: 1062 .

Helicodiscus (Hebetodiscus) subteres: Schlickum, 1976: 11 (pl. 2, fig. 35); Schlickum, 1979: 68 (fig. 2); Gall, 1980: 65; Kókay, 2006: 74 (pl. 27, figs. 14–16).

Material examined. BSPG 1952 XVIII 4 (1 spcm.).

Description. Shell diminutive, discoid, with flattened spire. Protoconch (~1¼ whorl) flat, apparently smooth; transition to teleoconch unclear. Teleoconch smooth, but with well-marked growth lines. Whorl profile convex. Suture well-marked, deep. Whorls regularly growing. Aperture round. Umbilicus wide.

Previous identification of the material. Gall (1980: Nr. 28): Helicodiscus (Hebetodiscus) subteres (Clessin) .

Discussion. The present specimen compares well to L. subteres, a species known from Miocene (MN 5–6) sites of Southern Germany and Hungary (Schlickum 1976, 1979; Kókay 2006). The species of Lucilla were usually classified in the genus Helicodiscus Morse and, more specifically, in the subgenus Hebetodiscus H.B. Baker. Hebetodiscus, however, was later considered a distinct genus by Bequaert & Miller (1973), which, in turn, was then regarded as a synonym of Lucilla by Falkner et al. (2002). As such, some authors (e.g., Hubricht 1985; Hotopp et al. 2010) state that this whole Helicodiscus complex should be revised. Until then, the current approach of treating Lucilla as a distinct genus (e.g., Moser et al. 2009; Gargominy et al. 2011; Welter-Schultes 2012) is followed here.

Paleoecological remarks. The two recent European Lucilla species are subterranean ( L. scintilla Lowe is even blind), living deeper in the soil than other land snails (Welter-Schultes 2012). If the extinct species shared this habit, the increased difficulty for their preservation would explain the scarce fossil record of the genus.