Biternatisporites gen. nov.—a new megaspore genus from the Middle-Carboniferous sediments of the Tunguska basin (Siberian platform, Russia)

The paper presents a new genus, Biternatisporites gen. nov., which is represented by a single species, B. compositus comb. nov.. This genus was found in the Middle Carboniferous sediments (Bashkirian age) of the Tunguska Basin, Russia. A description of the sediments where the new genus was found is given. The area of Biternatisporites gen. nov. represents a double ray system: large rays reach the edge of the megaspore, and small rays go beyond the corners of large rays. The new genus belongs to the first ecological and morphological type of megaspores, in terms of evolutionary development. This type is characterized by a simple morphological structure of the shell, consisting of the distal and proximal sides. On the proximal side there is an area bearing a tetrad scar and rare sculptural elements.