Rugalindrites cylindracea (Cornuel, 1841)

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

Rugalindrites cylindracea (Cornuel, 1841)

Plate 20: figs 1-9

* 1841 - Melania cylindracea sp. nov. - Cornuel: 289, pl. 15, fig. 14.

1852 - Actaeonina cylindracea (Cornuel). - d’Orbigny: 179, pl. 288, fig. 9?

1874 - Acteonina cylindracea d’Orbigny (Cornuel) - Loriol in Loriol and Pellat: 295, pl. 6, fig. 7.

1895 - Cylindrobullina cylindracea Cornuel - Cossmann: 57, pl. 3, fig. 1, pl. 4, fig. 1, 2.

1997 - Cylindrobullina cylindracea (Cornuel, 1841) - Fischer and Weber: 69.

2017 - Rugalindrites sp. - Gründel: 33, pl. 15, fig. D

Material.

Forty-eight mostly juvenile specimens from Saal, collection Lang, SNSB-BSPG 2021 XV 93-97.

Description.

A large specimen with damaged spire is 10 mm high. The shell is elongated fusiform. The last whorl is very high, cylindrical, tapering in abapical direction, embracing high on the previous whorl and covering most of it. The spire is relatively high for the genus and is acutely conical, consisting of several low whorls. A narrow but distinct horizontal ramp is formed early in ontogeny. The ramp is sharply demarcated from the whorl face by an edge. The shell is smooth. Growth lines are not visible, only on the ramp, remains of strengthened opisthocyrt growth lines are visible. The aperture is elongated, narrow and stretches over the entire height of the last whorl. Its adapical portion is narrow and acutely tapering. The abapical portion of the aperture is widened drop-shaped. The columellar portion of the aperture is covered by callus which also covers parts of the base. The abapical delimitation of the callus is formed by a somewhat oblique plait which also demarcates the columellar area from the abapical edge of the aperture. A further weak plait forms the outer edge of the callus of the aperture.

Remarks.

Columellar plaits are mostly not mentioned for Rugalindrites cylindracea possibly due to insufficient preservation of the specimens and due to the fact that the plaits are rather weak. Even in the present material, plaits are rarely visible.

Relationships.

Differences to Rugalindrites sp. 1 are discussed below. Cylindrobullina humbertina Buvignier sensu Cossmann (1895) has a weaker and oblique ramp and its bordering edge is less pronounced. Moreover, it lacks a columellar callus with plaits. Tornatina boutillieri Cossmann, 1895 has a lower spire and the last whorl is cylindrical with straight whorl face. Acteonina davidsoni Loriol, 1874 (in Loriol and Pellat) has a lower spire, broader whorls, the last whorl is cylindrical and has a straight whorl face; columellar plaits have not been mentioned for this species.

Figures

Plate 20. (1 - 9) Rugalindrites cylindracea (Cornuel, 1841). (1) SNSB-BSPG 2021 XV 93, Saal (collection Lang), lateral view, height 5 mm. (2) SNSB-BSPG 2021 XV 94, Saal (collection Lang), apical view, width 5.5 mm. (3 - 4) Saal (collection Lang), lateral and apical views (specimen lost). (5) SNSB-BSPG 2021 XV 95, Saal (collection Lang), aperture, height 3.5 mm. (6 - 7) SNSB-BSPG 2021 XV 96, Saal (collection Lang); (6) lateral view, height 8.5 mm; (7) aperture, height 3.5 mm. (8 - 9) SNSB-BSPG 2021 XV 97, Saal (collection Lang); (8) aperture, height 6 mm; (9) lateral view, height 9.5 mm. (10 - 12) Rugalindrites sp. 1, SNSB-BSPG 2021 XV 98, Saal (collection Lang); (10) lateral view, height 5.5 mm; (11) apical view, width 2.5 mm; (12) detail of ornament, height ca. 1.3 mm.