Diagnoza

Early coils have an ad- and an abapical row of cusps with several weak spiral ribs between them and axial ribs connecting the cusps. Later in ontogeny there are no axial ribs, only weak spiral ribs and (mostly) the adapical row of cusps. The abapical row forms a bulge with numerous small crenulae, but without spiral striae.

Porównanie

Amphitrochus smyntheus Laube, 1867 has very numerous and ontogenetically persistent axial ribs, the subsutural row of cusps is missing and the whole flank is covered with numerous spiral ribs. A. thouetensis (Hébert & Eudes-Deslongchamps, 1860) lacks spiral and axial ribs on early coils, several spiral striae run on the abapical row of cusps and the cusps are more numerous. A. keuppi Gründel, 2009 also has an adapical row of cusps on late coils, between the adapical and abapical row of cusps 2–4 clearly stronger and persistent spiral ribs are formed, between the abapical row of cusps and abapical suture there is a spiral rib, the crenulae of the abapical row are on late Turns significantly larger. A. erraticus Gründel & Koppka, 2010 lacks the adapical row of cusps; the abapical is more bulging, divided into two by a furrow, has numerous and smaller cusps, and several spiral striae run on it; a bend to the base is missing. A.? lacuna (Blake, 1907) has, among other differences, no second edge as a bend edge to the base and no cusps or radial folds in the base center.

Autekologia

Występowanie geograficzne

Only in type locality.

Zasięg czasowy

Middle Jurassic.

Materiały muzealne

Holotype (NHMW 1855/0040/0015a),paratypes (NHMW 1867/0008/0011a, b) and 16 other specimens.

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.