Diagnoza

Flanks of the conch subdivided into two zones by a spiral furrow or escarpment.

Porównanie

Unlike the studied specimens, in the lectotype of A. planidorsatus (Becker 1993b, pl. 11: 10) the spiral elevation is restricted to near the umbilicus. All of them show rounded tips of apertural auricles, which makes them different from other specimens attributed to the genus. Most of the specimens from Łagów are represented only by ventral parts of the body chamber, only one of them preserved the whole conch flank, with the lateral furrow. This situation seems to be similar to that in the holotype, as described by Dybczyński (1913). The specimen of Petter (1959, pl. 15: 30) from Gourara in Algeria, reillustrated by Becker (1993b) and classified by him in his A. nudus, shows a similar aperture to the Polish A. lateroconcavus, but narrower umbilicus.

There is an apparent evolutionary change in the lineage. The umbilicus is relatively wide in the geologically oldest specimens from Jabłonna (beds 21–25), with gently rounded margin and flat sides of the conch. In the somewhat younger material from Łagów (sample Ł-14), a shallow furrow in the middle of the flanks developed, achieving the form of a prominent escarpment in the youngest specimen from Jabłonna (bed 26). Closely similar form occurs also in the Prolobites horizon in vicinities of the village Spasskij in the South Urals (Perna 1914, pl. 2: 9).

Autekologia

Występowanie geograficzne

Jabłonna, Łagów-Dule; reworked at Sieklucki’s brickpit in Kielce.

Zasięg czasowy

Probably the late C. marginifera Zone, the P. trachytera Zone; and the L. styriacus Zone. 

Materiały muzealne

ZPAL: 7 specimens.

Literatura

Dzik, J. 2006. The Famennian "Golden Age" of conodonts and ammonoids in the Polish part of the Variscan sea. Palaeontologia Polonica 63, 1-359.