Sulcoactaeon sp. 1

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

Sulcoactaeon sp. 1

Plate 21: figs 6, 7

Sulcoactaeon leblanci ?1997 - Sulcoactaeon leblanci (Loriol, 1875) - Hägele: 118, p. 118 below, 2nd fig. from left.

Material.

One specimen from Saal, collection Lang, SNSB-BSPG 2021 XV 101.

Description.

The shell is 4.2 mm high. It is slender oval. The last whorl is higher than the distinctly elevated and gradate spire. The whorl height increases rapidly by a downward shift of the suture. The sutures are accentuated by the presence of a narrow ramp. The whorl face is weakly convex. The spire whorls have a suprasutural spiral furrow. The transition from whorl face to the strongly convex base is evenly rounded. The base is entirely covered by spiral furrows (ca. 15). The furrows are widely distant to each other on the adapical portion of the base and become increasingly more narrowly spaced towards the abapical portion of the base. The aperture is elongated oval and acute posteriorly. The outer lip is convex. The inner lip consists of the parietal and columellar lips that meet at an obtuse angle. The columella terminates abruptly at the anterior margin of the aperture.

Relationships.

Sulcoactaeon leblanci (Loriol) sensu Hägele (1997) is probably conspecific. However, its spire whorls are lower, it has a subsutural spiral cord, and the last whorl is broader and has a more convex outline.

Figures

Plate 21. (1 - 2) Ptychocylindrites condati (Guirand & Ogerien, 1865), Nattheim (collection Sauerborn); (1) apical view, width 5 mm; (2) lateral view, height 12 mm. (3 - 5) Volvocylindrites marcousana (Guirand & Ogerien, 1865). (3) SNSB-BSPG 2021 XV 99, Saal (collection Lang), lateral view, height 5.5 mm. (4 - 5) SNSB-BSPG 2021 XV 100, Saal (collection Lang); (4) lateral view, height 8.8 mm; (5) aperture, height 3.2 mm. (6 - 7) Sulcoactaeon sp. 1, SNSB-BSPG 2021 XV 101, Saal (collection Lang), lateral views, height 3.7 mm.