Foraminiferida Eichwald, 1830

Less, György, Özcan, Ercan, Papazzoni, Cesare A. & Stockar, Rudolf, 2008, The middle to late Eocene evolution of nummulitid foraminifer Heterostegina in the Western Tethys, Acta Palaeontologica Polonica 53 (2), pp. 317-350 : 331

Order Foraminiferida Eichwald, 1830 Family Nummulitidae de Blainville, 1827 Genus Heterostegina d’Orbigny, 1826

Type species: Heterostegina depressa d’Orbigny, 1826 , Recent , St. Helena Island .

Remarks.—Based on the qualitative and quantitative parameters evaluated above, the Western Tethyan late Bartonian to Priabonian Heterostegina can be grouped into three species. Due to the joint occurrence of the most advanced H. armenica and the most primitive H. reticulata in sample Keçili 11 and also to that of the most advanced H. reticulata and H. gracilis in samples Possagno 1 and 2, the stratigraphical succession of these species could be inferred.

Heterostegina armenica and especially H. reticulata form evolutionary lineages. Their intraspecific development can be characterized most effectively by the reduction of the undivided, post−embryonic chambers (X). Therefore they are subdivided into chronosubspecies by arbitrary limits of the mean values of this parameter. Table 6 illustrates the results of the t−test on parameter X in comparing the neighboring populations according to parameter X, in decreasing order. It demonstrates that the lineages are segmented at its weakest points, where p(t)−values are the lowest as compared to the neighboring values. The density of the segmentation is in accord with Drooger’s (1993: 30) proposals.