Bactroptyxis cf. fasciata (Voltz, 1836)

Plate 13: figs 3-5

?1836 - Nerinea fasciata Voltz - Bronn: 554, pl. 16, fig. 21.

Material.

One specimen (SNSB-BSPG 2021 XV 56) and one questionable specimen, both from Saal, collection Lang.

Description.

The bona fide specimen is 36 mm high. The shell is very slender. The whorl face is straight. The sutures are not impressed and only occasionally visible. The ornament is only preserved on the last whorl. It consists of four spiral cords of equal strength that are equally distant from each other. A knobby ornament is absent. An abapical spiral cord, probably representing the bordering spiral cord, is visible above the suture and marks the angular transition to the flat base. Only the inner lip of the aperture is preserved; it shows one parietal plait and two columellar plaits.

Remarks.

Nerinea fasciata sensu Bronn (1836) has the same shell shape as the present species and it has also four spiral cords, which are, however, of unequal strength.

Relationships.

Bactroptyxis teres ( Münster in Goldfuss, 1844) differs from Bactroptyxis cf. fasciata by having four strong spiral cords of equal strength and at equal distances. Bactroptyxis teres ( Münster) sensu Hägele (1997) has more and weaker spiral cords of unequal strength. Aptyxiella rupellensis d’Orbigny sensu Pchelintsev (1965) has higher whorls and more spiral cords. Aptyxiella inornata d’Orbigny sensu Maire (1913) has five spiral cords on the whorl face and a subsutural bulge; apertural plaits are not visible. Nerinea quadricincta Münster sensu Maire (1913, pl. 11, fig. 7) has two stronger spiral cords on the whorl face (unlike in Maire’s 1913, p. 93 description) and allegedly additional weak spiral cords that are unrecognizable, and it shows swellings near the sutures. These swellings form bulges on which the sutures are situated.