Evolution of the late carboniferous foraminiferal genus Fusiella Lee et Chen (Fusulinida)

The evolution of the genus Fusiella Lee et Chen, 1930 is investigated. Two species groups corresponding to the main evolutionary trends are recognized. The first, F. praecursor Rauser- F. acera M.-Macklay, belongs to the lineage of fusiform taxa, with straight septa and axial filling along the shell axis. In the second, F. praecursor Rauser- F. excelsa Suleimanov, the cylindrical shell is developed; the axial filling is reduced; the septa are slightly folded in the polar regions; and the lateral sides of the shell become slightly plicate. The stratotype and reference sections of the Moscovian and Kasimovian Stages of the Moscow Syneclise have yielded species of the first phylogenetic lineage. A new species, Fusiella pseudorawi sp. nov., is described.