Diagnoza

The shell is trochoid with a blunt apex. The first teleoconch whorl is rounded, the second whorl has a flat lateral flank and, beginning with the third whorl, the whorls become concave. The suture is hardly incised. There are five spiral ribs on the first teleoconch whorl; later, their number increases to 8-9 and the ribs cover the visible part of the whorl. Later in ontogeny the rib corresponding to the angulation of the whorl migrates adapically, and an additional rib emerges beneath. Blunt and weak nodes are present exclusively on the adapicalmost rib of the early teleoconch whorls and disappear later in ontogeny. The base is densely covered by about twenty spiral ribs, which become somewhat more widely spaced near the centre.

Porównanie

Trochus bijugatus Quenstedt, 1858 from the Bajocian/ Bathonian of Germany, has a broader shell, less numerous spiral ribs on the flanks, and no nodes on the uppermost spiral rib.

Autekologia

Występowanie geograficzne

Kłęby (Western Pomerania), Poland

Zasięg czasowy

late Oxfordian.

Materiały muzealne

Two specimens in Schmidt (1905) collection; moreover nine shells (BGR, Buchholz, GG, and ZPAL).

Literatura

Dmoch, I. 1971. Osady i fauna górnojurajska z Kłębów na Pomorzu Zachodnim. Studia Societatis Scientarum Torunensis. Sectio C (Geographia et Geologia), 7, 1‒60.

Gründel, J & Kaim, A. 2006. Shallow-water gastropods from Late Oxfordian sands in Kłęby (Pomerania, Poland). Acta Geologica Polonica 56, 2, 121‒157.

Karczewski, L. 1980. Gromada Gastropoda Cuvier, 1797 In: Malinowska, L. (Ed.), Budowa Geologiczna Polski. Tom III: Atlas skamienianiałości przewodnich i charakterystycznych. Część 2b, Mezozoik, Jura, 414- 434. Wydawnictwa Geologiczne; Warszawa.

Schmidt, M. 1905. Über Oberen Jura in Pommern. Abhandlungen der Königlich Preußsischen Geologischen Landesanstalt und Bergakademie, Neue Folge, 41, 1-222.