Two new species of silica-scaled chrysophytes (Chrysophyceae, Synurales) Mallomonas kicherica and M. sibirica water bodies of Eastern Siberia, Russia

Two new species of Chrysophytes, Mallomonas kicherica and M. sibirica (order Synurales) were described in several water bodies in Eastern Siberia based on the ultrastructure of silica scales. These species belong to section Striatae. M. kicherica is characterised by scales with labyrinth-like reticulation on the dome and transverse ribs connected by short ribs-jumpers. This species is most similar in scale ultrastructure to M. striata var. balonovii. M. kicherica was found in the mouth of Kichera River, a tributary of Lake Baikal. M. sibirica is characterised by scales with a well-developed secondary layer on the shield in which rounded depressions are located. This species is most similar in scale ultrastructure to M. pechlaneri. M. sibirica was registered in different waters of Eastern Siberia under various ecological parameters-in the mixing zone of the Yenisei River and the Kara Sea, Lake Baikal, and in lakes Ulu, Vorota and Labynkyr (Yakutia).