Ptygmatis mandelslohi (Bronn, 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

Ptygmatis mandelslohi (Bronn, 1836)

Plate 9: figs 1-5

*1836 - Nerinea mandelslohi sp. nov. - Bronn: 553, pl. 6, fig. 26.

1844 - Nerinea mandelslohi Bronn - Goldfuss: 39, pl. 175, fig. 4.

non v1881-1884 - Nerinea mandelslohi Bronn - Quenstedt: 535, pl. 206, figs 11, 12.

?1882 - Ptygmatis mandelslohi Bronn - Schlosser: 81, pl. 11, fig. 14.

1893 - Ptygmatis bruntrutana (Thurmann), Zittel - Loriol in Loriol and Lambert: 25, pl. 2, figs 6, 7.

?part1979 - Ptygmatis bruntrutana (Thurmann, 1832) - Wieczorek: 324, pl. 8, figs 2-5, 7; textfig. 10, 14, 19-21.

1997 - Nerinea bruntrutana (Thurmann, 1832) - Hägele: 128, fig. p. 128 upper left.

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

2017 - Nerineoidea Nr. 6 - Gründel: 33, pl. 14C.

Material.

Four specimens from Saal: three specimens, collection Lang, two of which are illustrated (SNSB-BSPG 2021 XV 27, 28), one specimen collection Keupp, SNSB-BSPG 2021 XV 29, and one additional questionable specimen from Saal (collection Lang).

Description.

The illustrated specimen (Plate 9 : figs 1-4) is 35 mm high. The shell is moderately wide. The early whorls increase more rapidly in width than later ones producing slightly cyrtoconoid outline. The whorls are much wider than high. The whorl face is straight to slightly concave. The sutures are hardly impressed but visible. The whorls have a weak subsutural spiral furrow; apart from that, the whorls are smooth. The base is weakly convex and demarcated from whorl face by a sharp, almost rectangular edge. The base is smooth and narrowly phaneromphalous. The aperture is rhomboid. The inner lip has a strong parietal plait and two columellar plaits. The adapical columellar plait is weaker than the abapical one. A weak palatal plait is visible.

Remarks.

According to Fischer and Weber (1997), P. mandelslohi is a junior synonym of P. bruntrutana . The specimen figured as P. bruntrutana by Fischer and Weber (1997, pl. 10, fig. 6) is slenderer and has higher whorls than Ptygmatis mandelslohi . Regarding these characters, this specimen agrees with Nerinea bruntrutana as illustrated and described by Thurmann and Étallon (1861-1864).

The cyrtoconoid shape (produced by slower increase in width during ontogeny) is particularly characteristic of P. mandelslohi . This character is absent in most otherwise similar species. However, it is commonly unclear whether the lack of a cyrtoconoid shape is real or has not been recognized (e.g., due to preservation). This makes the differentiation of P. mandelslohi from similar species difficult. Otherwise similar species that also have a cyrtoconoid shape may have an entirely different plait-pattern in the aperture, i.e., having only a single, strong parietal plait as is typical for the genus Cryptoplocus (for instance Cryptoplocus picteti Gemmellaro, 1870: 39, pl. 6, fig. 8). As a consequence, a correct generic assignment of such species is impossible if the plait-pattern is unknown.

Relationships.

Cryptoplocus depressus (Voltz, 1836) is distinctly larger, has whorls that are regularly increasing in width so that the shell is not cyrtoconoid, a wider umbilicus, and only a single parietal plait. Ptygmatis carpathica Zeuschner sensu Zeuschner (1850) and Zittel (1873) has a distinct bulge at the transition from whorl face to base, a wider umbilicus, and a weakly concave whorl face. Ptygmatis carpathica (Zeuschner) and P. salomoniana Cotteau, both sensu Loriol in Loriol and Lambert (1893), are slenderer, have a distinct bulge at the transition from whorl face to base, and a more or less distinctly concave whorl face.

Ptygmatis carpathica (Zeuschner) sensu Gemmellaro (1870) shows similar differences. Moreover, it is distinctly larger and the abapical spiral bulge is visible distinctly above the suture. Nerinea carpathica Zeuschner sensu Thurmann and Étallon (1861-1864) is slenderer and has a concave whorl face. Cryptoplocus depressus (Bronn ex Voltz, 1836) sensu Fischer and Weber (1997: pl. 10, fig. 5, non fig. 4) is slenderer and has higher whorls. Cerithium climax Zittel sensu Blaschke (1911) has more and lower whorls; its transition to the base is seemingly more strongly rounded. Ptygmatis submirabilis Pchelintsev, 1965 is larger and slenderer, its spiral bulge at the transition from whorl face to base is more pronounced and visible above the suture.

Figures

Plate 9. Ptygmatis mandelslohi (Bronn, 1836). (1 - 4) SNSB-BSPG 2021 XV 27, Saal (collection Lang); (1) base, width 15 mm; (2 - 3) lateral views, height 35 mm; (4) last whorl with aperture, height 12 mm (original to Gruendel 2017, fig. 14 C). (5) SNSB-BSPG 2021 XV 28, Saal (collection Lang), last whorl with aperture, width 10 mm.