Placoseris de Fromentel, 1863b

Loeser, Hannes, Werner, Winfried & Darga, Robert, 2023, Middle Cenomanian coral fauna from the Rosssteinalmen (Northern Calcareous Alps, Bavaria, Southern Germany) - a revised and extended version, Zitteliana 97, pp. 89-147 : 89

Placoseris de Fromentel, 1863b

Type species.

Placoseris patella de Fromentel, 1863b.

Description.

Solitary cylindric coral. Corallite outline circular or elliptical, centre slightly depressed. Symmetry of septa irregular radial. Synapticulae moderately common. Columella absent or developed as some small elements, presumably trabecular extensions of septal inner margins. Endotheca consists of numerous dissepiments. Wall absent or epithecal.

Remarks.

As already explained in Löser et al. (2021b), in the historic literature the genus Placoseris was considered synonymous with Acrosmilia d’Orbigny, 1849. Acrosmilia is a conceptual genus; the type specimen of the type species is available but so poorly preserved that important diagnostic features, such as the presence or absence of pennulae or the amount of septal perforation, cannot be observed. For this reason, the genus Leptophyllia Reuss, 1854 was applied ( Löser et al. 2019) in place of Acrosmilia . Leptophyllia was for a long time considered to be a junior synonym of Acrosmilia . The study of type specimens and topotypical material has shown that Leptophyllia belongs to the mainly Late Cretaceous family Synastraeidae and is restricted to the Late Cretaceous, whereas Placoseris belongs to the Jurassic and mainly Lower Cretaceous family Latomeandridae . Leptophyllia has thicker and less perforate septa, whereas in Placoseris the septa are thinner and more perforate at the inner margin. Moreover, the septa are often connected to each other in the latter, a characteristic that is less common in Leptophyllia (see Löser et al. 2019 for details).