Diagnoza

The shell seams are recessed. Two strong spiral ribs can be seen on early coils, which are roughly perpendicular to each other. On the last coil there are 4–5 spiral ribs. Further spiral ribs are located between the two spiral ribs edging the outline and between these and the abapical seam. Axial ribs traverse the spiral ribs and extend from seam to seam. On the penultimate coil, the adapical of the spiral ribs edging the outline becomes a humped keel, the abapical weakens to a weaker spiral rib. On the last coil, only the strongly accentuated keel and weaker spiral ribs are formed. At one point the keel is thickened. Only on the last turn is a second keel visible. The base is also covered with spiral ribs that vary in thickness. It ends in an approximately vertical (broken) rostrum.

Porównanie

Similar P. hamus (Eudes-Deslongchamps, 1843) and Pterocera deslongchampsi d’Orbigny, 1850 have more keeled coils and the cross-section of earlier coils is not octagonal. Rostellaria seminuda Hébert & Eudes-Deslongchamps, 1860 is larger and slimmer, the early coils are clearly keeled and the axial ribs are less numerous.

Autekologia

Występowanie geograficzne

Northern Germany and Poland (Balin).

Zasięg czasowy

Mid Jurassic

Materiały muzealne

3 specimens from Balin (NHMW 1867/0008/0002 a-c).

Literatura

Gründel, J. 2001. Neritimorpha und weitere Caenogastropoda (Gastropoda) aus dem Dogger Norddeutschlands und des nordwestlichen Polens. Berliner geowissenschaftliche Abhandlungen, Reihe E, 36, 45–99.

Gründel, J. 2012. Neubearbeitung der von Laube 1867 beschriebenen Gastropoden fauna aus dem mittleren Jura von Balin/Polen. Annalen des Naturhistorischen Museums in Wien. Serie A, 114, 193–288.

Laube, G. C. 1867. Die Gastropoden des braunen Jura von Balin. Denkschriften der kaiserlichen Akademie der Wissenschaften, 28, 1–28.