Diagnoza

Porównanie

The sculpture consists of two strong spiral ribs (the adapical is a little stronger), which are perpendicular to each other (the adapical a little above the center of the coil) and the edges of the octagonal coil outline. A third, somewhat weaker spiral rib lies just above the abapical suture. The whole flank is densely covered with weak spiral ribs: approx. 10 between the adapical suture and the adapical strong spiral ribs, between the other strong spiral ribs 3–4 each. About 15 axial ribs per turn extend from seam to seam. They are most strongly developed between the two strong spiral ribs. At least the last coil shows two clear varices. The convex base is not offset. The narrow oval aperture ends in a clear sipho abapically. Similar Diarthema paradoxum (Eudes-Deslongchamps, 1843) has fewer axial ribs, the spiral ribs are less numerous and stronger and on the base, strong spiral ribs alternate with weaker spiral ribs. Alaria (Pterocera) atractoides Eudes-Deslongchamps, 1843 has keeled coils in a similar sculpture. Genus Brachytrema has a similar sculpture.

Autekologia

Występowanie geograficzne

Balin, Poland

Zasięg czasowy

Mid Jurassic

Materiały muzealne

4 specimens (NHMW 1853/0038/0082).

Literatura

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.