Aptyxiella planata (Quenstedt, 1858)

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

Aptyxiella planata (Quenstedt, 1858)

Plate 1: figs 4-6

*1858 - Nerinea planata - Quenstedt: p. 770, pl. 94, figs 31, 32.

v1881-1884 - Nerinea planata Qu. - Quenstedt: p. 554, pl. 207, figs 5-7, 8?

1901 - Aptyxiella planata Quenstedt - Geiger: p. 276.

1997 - Aptyxiella planata (Quenstedt) - Hägele: p. 133, fig. p. 133 upper right.

Material.

One specimen (SNSB-BSPG 2021 XV 1) and four questionable fragments from Nattheim ( Tübingen, Quenstedt collection).

Description.

The shell is high-spired and very slender. It is 70 mm high (apex missing). The whorls are high with a straight to slightly concave whorl face and slowly increasing in width. The suture is oblique and situated on a slightly elevated bulge formed by two adjoined whorls. No ornament is visible (due to preservation?). The base is flat and demarcated from whorl face by a sharp angulation, and lacks visible ornament. The aperture is elongated, higher than wide, rhomboid, and has a distinct, oblique siphonal canal (partially broken). Plaits are absent.

Remarks.

The four fragments from the Tübingen collection are poorly preserved and might represent different species. According to Geiger (1901, p. 277), the whorls are ornamented with numerous spiral cords of various strength which are, however, destroyed by the coarse silicification of the specimens from Nattheim (if they were present at all).

Aptyxis planata Quenstedt sensu Schlosser (1882) differs from the studied specimens by having spiral cords, a broader shape, lower whorls and more oblique sutures. According to Schlosser (1882, p. 77) "the only specimen housed in the Munich Museum" shows ornamentation. However, our study of the specimen could not confirm this. The very similar (identical?) Cossmannea? quenstedti Geiger, 1901 has a columellar plait.

Figures

Plate 1. (1 - 3) Cossmannea desvoidyi (d'Orbigny, 1851). (1 - 2) collection Sauerborn, Nattheim area; (1) lateral view, height 23.8 cm; (2) last whorls with aperture, height 8 cm. (3) University Tuebingen, collection Quenstedt), Nattheim, lateral view, height 130 mm (original of Quenstedt 1881 - 1884, pl. 205, 60). (4 - 6) Aptyxiella planata (Quenstedt, 1858), SNSB-BSPG 2021 XV 1, Nattheim-Rinderberg; (4 - 5) lateral views, height 70 mm; (6) aperture, height of detail 70 mm. (7) Aptyxiella quenstedti Geiger, 1901, Nattheim, lateral view (copy from Geiger 1901, pl. 11, fig. 1).