Merica crenata (Hörnes, 1856) Harzhauser & Landau, 2012

Harzhauser, Mathias & Landau, Bernard, 2012, A revision of the Neogene Cancellariid Gastropods of the Paratethys Sea 3472, Zootaxa 3472, pp. 1-71 : 28-29

Merica crenata (Hörnes, 1856) nov. comb.

Figs 6G 1–G 3, 6H 1–H 3

Cancellaria crenata Hörnes 1856: 679 , pl. 52, figs 4a–b.

Cancellaria (n. Trigonostoma ) crenata M. Hoern. — Hoernes & Auinger 1890: p. 277.

Cancellaria (Trigonostoma) crenata Hörnes — Sieber 1936: 87.

Type material. NHM Vienna ( Austria); see below for details .

Studied material. 2 spec. Grund ( Austria) NHMW 2009 z0098/0021.

Illustrated material. Figs 6G 1–G 3: specimen illustrated in Hörnes (1856, pl. 52, figs 4a–b), Grund ( Austria), height: 20.2 mm, width: 13.2 mm, NHMW 2009 z0098/0021, holotype by monotypy. Figs 6H 1–H 3: Grund ( Austria), height: 25.8 mm, width: 17.1 mm, NHMW 2009 z0098/0021.

Description: The ovoid shell consists of a low spire of moderately convex whorls and a large, evenly convex last whorl, separated by a narrow but deeply canaliculate suture. This suture produces a small tip of the adapical part of the elongate ovoid aperture. The protoconch is poorly preserved but seems to consist of less than two whorls of which the last one is high and only weakly convex, forming rather steep flanks. The teleoconch sculpture starts with five spiral ribs composed of small beads, which arise at the intersections with the opisthocyrt axial ribs. The spirals increase to seven on the last spire whorl and develop a regular, narrowly spaced pattern of beaded spirals on the last whorl. The interspaces between the axial ribs become wider on the last whorl and may form weak varices. The concave columella bears a strong central columellar fold, which is flanked by an indistinct parietal swelling above and two oblique folds below; outer lip thin, non-callused, serrated with short lirae within; parietal and columellar calluses well delimited but thin, poorly expanded; columellar callus erect. The umbilicus is narrow.

Discussion. Hölzl (1973) mentions this species also in a list of Ottnangian (= middle Burdigalian) gastropods from Bavaria, without providing any description or illustration. In respect to the generally very poor preservation of that material from the Kaltenbachgraben and Gernergraben we doubt the identification. None of the species from the Early Miocene of France and Italy seems to be related to this rare species.

The species is reminiscent of the extant Merica melanostoma ( Sowerby, 1849) in shape and sculpture. We place this species in Merica based on its excavated columella and the lack of a dominant axial sculpture. The extant Indo-West-Pacific species Merica elegans (G.B. Sowerby I, 1822) and Merica sinensis ( Reeve, 1856) are reminiscent of the Paratethyan species concerning sculpture and columellar structure but have higher spires and lack the deep suture.

Distribution. A very rare species, which is known so far only from a single Early Badenian locality.

Paratethys —Badenian: North Alpine Foreland Basin ( Austria: Grund).