Ptygmatis? tornata (Quenstedt, 1852)

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

Ptygmatis? tornata (Quenstedt, 1852)

Morphotype 2 Plate 10: figs 11, 12

2017 - Nerineoidea Nr. 2 - Gründel: 33, pl. 13D.

Note.

In some specimens, the ramp is not bordered by a sharp crest, but by a more or less pronounced band that is demarcated from the concave part of the whorl face by another edge; there seem to be transitions between both varieties.

Remarks.

Two poorly preserved fragments of Nerinea cochlearis Quenstedt, 1881-1884 are present in the Quenstedt collection ( Tübingen), both probably representing juveniles. Shape and ornament match the description of Ptygmatis tornata given above, as does the number and position of the plaits. Their base is umbilicated. However, these two specimens are too poorly preserved for a safe identification as Ptygmatis tornata .

It remains unclear whether N. terebra Schübler in Zieten and N. incavata Bronn are conspecific with N. tornata Quenstedt. At least for N. terebra this is likely, because this species was described from Nattheim as is also the case for Nerinea cochlearis . Both, N. terebra and N. incavata , would have priority over N. tornata Quenstedt.

Relationships.

Numerous similar species have been described which are hardly distinguishable based on study of the literature alone. In the following, differences to middle Oxfordian and to early Tithonian taxa are discussed.

Nerinea mandelslohi Bronn sensu Zeuschner (1850) has higher whorls that are more rapidly increasing in width. Nerinea suevica Quenstedt sensu Schlosser (1882) has higher whorls, and only 3 apertural plaits are known for this species. Aptyxis paradoxa Schlosser, 1882 lacks plaits and also shows other differences. Bactroptyxis cassiope d’Orbigny sensu Fischer and Weber (1997) has higher whorls, its whorl face is less concave and it has less pronounced bulges; its sutures are situated on the bulge. Nerinea partschi Peters, 1855 closely resembles Ptygmatis? tornata but has higher whorls and lacks an open umbilicus. Nerinea gosae Roemer sensu Goldfuss (1844) resembles the present material in shell shape but its sutures are situated on the bulge. The latter is also the case in Nerinea acteon d’Orbigny sensu Cossmann (1898), Nerinea baillei Maire, 1913, and N. castor d’Orbigny sensu Maire (1927). Nerinea bruntrutana Thurmann sensu Goldfuss (1844) resembles Ptygmatis tornata morphotype 2 in having a band-like, broadened bulge; however, its whorls increase more rapidly in width so that its shape is more broadly conical and it has two palatal plaits.

Figures

Plate 10. Ptygmatis? tornata (Quenstedt, 1852). (1 - 10) Ptygmatis? tornata (Quenstedt, 1852) morphotype 1. (1) SNSB-BSPG 2021 XV 32; Saal (collection Lang); lateral view, height 14 mm. (2) SNSB-BSPG 2021 XV 33, Saal (collection Lang), lateral view, height 65 mm (original to Gruendel 2017, fig. 13 E). (3 - 4) SNSB-BSPG 2021 XV 34, Saal (collection Lang); (3) lateral view, height 20 mm; (4) base, width 7 mm). (5) SNSB-BSPG 2021 XV 35, Saal (collection Lang), lateral view, height 19 mm. (6 - 7) SNSB-BSPG 2021 XV 36, Saal (collection Lang); (6) lateral view, height ca. 50 mm; (7) aperture, width 15 mm. (8 - 9) Lectotype; University Tuebingen (collection Quenstedt), Nattheim, shell in lateral views, height ca. 30 mm (original Quenstedt 1881 - 1884, pl. 205, fig. 67). (10) University Tuebingen (collection Quenstedt), Nattheim, lateral view, height ca. 45 mm (original Quenstedt 1881 - 1884, pl. 206, fig. 68). (11 - 12) Ptygmatis? tornata (Quenstedt, 1852) morphotype 2; (11) SNSB-BSPG 2021 XV 37, Saal (collection Lang), lateral view, height 29 mm. (12) morphotype 2, SNSB-BSPG 2021 XV 38, Saal (collection Lang), lateral view, height 42 mm (original to Gruendel 2017, fig. 13 D).