Cryptoplocus depressus (Voltz, 1836)

Gruendel, Joachim, Keupp, Helmut, Lang, Fritz & Nuetzel, Alexander, 2022, Late Jurassic (Upper Kimmeridgian) Heterobranchia (Gastropoda) of the coral-facies of Saal near Kelheim and the viciniy of Nattheim (Germany), Zitteliana 96, pp. 179-221 : 179

Cryptoplocus depressus (Voltz, 1836)

Plate 14: figs 1-5

*1836 - Nerinea depressa Voltz - Voltz: 540.

1836 - Nerinea depressa Voltz - Bronn: 549, fig. 17.

?1858 - Nerinea depressa Voltz - Quenstedt: 765, pl. 94, figs 1, 2.

1874 - Trochalia depressa (Voltz) Sharpe - Loriol in Loriol and Pellat: 312, pl. 7, fig. 2.

v1881-1884 - Nerinea depressa Voltz, 1836 - Quenstedt: 546, pl. 206, figs 48-53.

1898 - Cryptoplocus depressus Voltz - Cossmann: 158, pl. 11, figs 33, 34; pl. 12, figs 3, 4, 7, 11, 12.

non 1997 - Cryptoplocus depressus (Bronn ex Voltz, 1836) - Fischer and Weber: 41, pl. 10, figs 4, 5.

?1998 - Cryptoplocus cf. picteti Gemmellaro, 1864 - Wieczorek 316, pl. 1, fig. 5.

Material.

Seven fragments from Nattheim ( Tübingen, collection Quenstedt), three specimens from the vicinity of Nattheim (collection Sauerborn) and three specimens from Saal (collection Lang), one of which illustrated herein (SNSB-BSPG 2021 XV 106).

Description.

The largest specimen is 96 mm high. The shell is moderately broad. The whorls are regularly increasing in width throughout ontogeny. They are distinctly wider than high. The whorl face is straight. The sutures are not impressed and hardly visible. No ornament is visible on whorl face. The base is weakly convex. The transition from base to whorl face forms a pronounced angular edge. The base has a wide umbilicus that is surmounted by a bulge. The base is otherwise smooth. The aperture is strongly damaged in all studied specimens, only a strong parietal plait is visible.

Remarks.

Quenstedt’s (1881-1884) material of Cryptoplocus depressus from Nattheim consists of seven poorly preserved fragments. Their shell shape is mostly not recognizable. The specimen illustrated by Quenstedt (1881-1884: pl. 206, fig. 52) (here: Plate 14 : figs 3, 4) is a fragment of 37 mm height. It has a strong parietal plait.

Relationships.

Differences to Ptygmatis mandelslohi are discussed where that species is treated. Nerinea depressa Voltz sensu Zeuschner (1850) has a distinct subsutural furrow, and its whorl face has a concave zone in lateral view. Cryptoplocus depressus Voltz sensu Yin (1931) is slenderer and has lower whorls. Ptygmatis meneghini Gemmellaro sensu Yin (1931) is slenderer and has a suprasutural bulge that is delimited adapically by a furrow. Nerinea terebra Schübler in Zieten, 1830 is slenderer, has a bulge at the sutures and its whorl face is concave.

Figures

Plate 14. (1 - 5) Cryptoplocus depressus (Voltz, 1836). (1 - 2) Collection Sauerborn, Nattheim area; (1) l ateral view, height 78 mm; (2) base, width 29 mm. (3 - 4) University Tuebingen (collection Quenstedt), Nattheim; (3) lateral view, height 37 mm; (4) last whorls with aperture, width 25 mm. (5) SNSB-BSPG XV 106, Saal (collection Lang), columellar section, height 47 mm. (6) Cryptoplocus subpyramidalis (Muenster in Goldfuss, 1844), SNSB-BSPG 2021 XV 61, Saal (collection Lang), lateral view, height 103 mm.