Nummulites mihashamensis n. sp. (N. laevigatus group) from the Middle Eocene, East Beni Mazar, Nile Valley, Egypt

Abstract

Nummulites mihashamensis n. sp., typical of N. laevigatus group, is biometrically studied, described and illustrated through both generations from limestone bank of Late Lutetian Midawara Formation of Gebel El Mihasham, recorded from east Beni Mazar, Nile Valley, Egypt. Detailed investigations of the new species: N. mihashamensis n. sp. and its ontogenetic growth stages are discussed. The biometric analysis demonstrated that N. mihashamensis n. sp. lies phylogenetically in parallel Lineage to that of N. crassichordatus Boukhary et al. 2010. Both species are chronostratigraphically coeval belonging to Late Lutetian age, (SBZ 16 of Serra-Kiel et al. 1998, PZ P12A, 42.3 – 40.2 Ma, see BouDgher-Fadel 2013). N. crassichordatus from Mokattam is considered to be the ancestral species of N. bartovigatus Boukhary and Hussein 2002 from Helwan. To compare species of N. laevigatus group phylogenetically, Nummulites mihashamensis n. sp., N. crassichordatus and N. bartovigatus are useful in southern Tethys in age dating compared with those in northern Tethys of Schaub 1981. It is evident that there is speciation between the northern and southern Tethys ocean as Nummulites are bottom dwellers which they could not cross this deep basin, the connection of these species was more likely through the shallow shelves.