Bactroptyxis teres ( Muenster in Goldfuss, 1844)

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

Bactroptyxis teres ( Muenster in Goldfuss, 1844)

Plate 13: figs 1, 2

*1844 - Nerinea teres Münster - Goldfuss: 43, pl. 176, fig. 3.

?1997 - Nerinea teres ( Münster, 1844) - Hägele: 136, fig. p. 136 lower left, pl. 13, fig. 6.

Material.

Two specimens from the Nattheim area (collection Sauerborn).

Description.

A specimen is 28 mm high. The shell is very slender. The sutures are indistinct and hardly recognizable. The whorl face is straight. The ornament is weak (due to preservation?) consisting of four spiral cords on the whorl face at about same distance to each other. Two spiral cords are situated directly near the sutures, two other cords are in the middle portion of the whorl face. The transition from whorl face to base is angular. The aperture has two columellar, two palatal plaits, and one parietal plait.

Remarks.

Bactroptyxis teres ( Münster) sensu Hägele (1997) is probably identical but has three columellar and three palatal plaits according to Hägele (1997).

Relationships.

Bactroptyxis? tricincta Goldfuss sensu Quenstedt (1881-1884) is distinctly larger, not as slender and has only three spiral cords (suprasutural spiral cord lacking). Bactroptyxis sp. cf. fasciata (Voltz, 1836) (see below) is very similar to Bactroptyxis teres but has much more distinct spiral cords. However, this could be due to preservation and both taxa could represent a single species. Nerinella bipunctata (Quenstedt) sensu Hägele (1997) has nodular spiral cords and it has only one columellar and one parietal plait. Aptyxiella ewaldi Geiger, 1901 closely resembles Bactroptyxis teres in shape and ornament but lacks plaits in the aperture according to Geiger (1901). Nerinea vallonia Loriol in Loriol and Cotteau (1868) differs by having 7-8 spiral cords on the whorl face and only a weak columellar plait. Aptyxiella inornata d’Orbigny sensu Maire (1913) has an ornament of five spiral cords of unequal strength and lacks plaits in the aperture.

Figures

Plate 13. (1 - 2) Bactroptyxis teres (Muenster in Goldfuss, 1844), from the Nattheim area (collection Sauerborn); (1) last whorl with aperture, height 11 mm; (2) lateral view, height 29 mm. (3 - 5) Bactroptyxis cf. fasciata (Voltz, 1836), SNSB-BSPG 2021 XV 56, Saal (collection Lang); (3) detail of ornament, width 4.5 mm; (4) lateral view, height 36 mm; (5) aperture, width of whorl 4.6 mm. (6 - 8) Bactroptyxis? subcochlearis (Muenster in Goldfuss, 1844). (6 - 7) SNSB-BSPG 2021 XV 57, Saal (collection Neubauer); (6) detail of ornament, height 11.5 mm; (7) lateral view, height 55 mm. (8) SNSB-BSPG 2021 XV 58, Saal (collection Lang), lateral view, height 29 mm. (9 - 10) Bactroptyxis? tricincta (Muenster in Goldfuss, 1844). (9) SNSB-BSPG 2021 XV 52, Saal (collection Lang), lateral view, height 48 mm (original to Gruendel 2017, fig. 14 B). (10) SNSB-BSPG 2021 XV 52, Saal (collection Lang), detail of shell in lateral view, height 21 mm. (11 - 16) Bactroptyxis? tricincta (Muenster) sensu Quenstedt (1881 - 1884). (11 - 12) Collection University Tuebingen (collection Quenstedt); Nattheim, lateral views, height 29 mm (original to Quenstedt 1881 - 1884, pl. 207, fig. 9). (13) SNSB-BSPG 2021 XV 53, Saal (collection Lang), lateral view, height 64 mm. (14) SNSB-BSPG 2021 XV 54, Saal (collection Lang), lateral view, height 55 mm. (15 - 16) SNSB-BSPG 2021 XV 55, Saal (collection Lang); (15) lateral view, height 72 mm; (16) last whorl, width 17 mm.