Biternatisporites Mashchuk, 2022

Mashchuk, Irina M. & Frolov, Аndrey O., 2022, Biternatisporites gen. nov. - a new megaspore genus from the MiddleCarboniferous sediments of the Tunguska basin (Siberian platform, Russia), Phytotaxa 576 (2), pp. 227-232 : 229

Genus Biternatisporites Mashchuk , gen. nov.

Generic diagnosis:—The megaspores are round to irregularly triangular in polar projection; their diameter is 750–850 μm. The area is star-shaped and consists of three long and three short alternate rays projecting beyond the proximal surface of the megaspore. The lips are low, located in the middle of the short rays of the area and extend almost to their end.

Comparison:—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 edges of the tetrad scar are low, located in the middle of the short rays of the area and extend almost to their ends. This area structure clearly distinguishes Biternatisporites gen. nov. from the genera Tuberculatisporites and Laevigatisporites , in which the area is not expressed and has a simple three-beam scar of the dehiscence, often hidden by folds of a thin shell. The new genus is related to Aphanozonatisporites , but differs from it in the presence of robust rays forming an original areola, and in having smaller dimensions than in Aphanozonatisporites .

Type species:— Biternatisporites compositus ( Mashchuk 2010: 58) Mashchuk , comb. nov.

Etymology:—from Latin words: Bi- = ‘double’; ternatus = ‘triplet’; thus ‘double triplets (biternate)’ and sporites = ‘spore, pollen’.