Resumen de Phenotypic variability of General Heterolepa and Gemellides from the Central Paratethys Oligocene and Miocene

Katarína Holcová, Hana Maslowská

• The species in Gemellides-Heteropela pleux can be distinguished by means of the biometrical analysis of specimens from the Oligocene and Miocene of the Central Paratethys using k-means clustering, discriminant analysis and stepwise regression. Gemellides bullatus (Franzenau) occurs only in Lower Oligocene and it is characterized mainly by appearance of the aperture on the spiral side of the test. Heterolepa dutemplei (Orbigny) changes gradually in the analysed time interval: number of chambers in the whorls decrease, lobate outline of the test appears and sutures become more straight. Morphometrical variability is not connected with changes of paleoenvironment: smaller tests have been observed only in hyposaline environment.