Morphological variability of some species from the genus Aulacoseira Thw. (Bacillariophyta)

摘要

Electron microscopic studies of the samples of Bacillariophyta from Lake Elgygytgyn (Chukotka, Russia) and water bodies of its basin have showed that centric diatoms from the genus Aulacoseira Thw. (A. distans var. septentrionalis Camb. et Charl. and A. perglabra (Ostr.) Haw. emend. Genkal et Kharitonov) demonstrate significant variability of morphological features (valve diameter, height of the mantle, number of row and areolae in 10 mu m, number of spines in 10 mu m, and location of areolae on the valve face). A broad diagnosis of A. perglabra is presented.