Lineage of Arxina schwageri (Silvestri, 1928) new genus (Nummulitacea) from Middle Eocene of Egypt and Sultanate of Oman

Four species, Arxina parva (Douville, 1930), Arxina cf. schwageri (Silvestri, 1928) A. schwageri (Silvestri, 1928) and Arxina sp. cf. alpina (Douville, 1916) assigned to the newly erected genus Arxina, are recorded from the Middle Eocene of Egypt and Sultanate of Oman. The phylogenetic trend of these species exhibits a progressive increase in the size, a flattening of the test and a general trend of the coalescence of granules which become smaller in size.