A survey of 1488 records of myxomycetes found within a mountain taiga-dry steppe vegetation gradient has identified 161 species and 41 genera from the southeastern Altay mountains and adjacent territories of the high Ob' river basin. Of these, 130 species were seen or collected in the field and 59 species were recorded from moist chamber cultures. Data analysis based on the species accumulation curve estimates that 75-83% of the total species richness has been recorded, among which 118 species are classified as rare (frequency < 0.5%) and 7 species as abundant (> 3% of all records). Among the 120 first species records for the Altay Mts. are 6 new records for Russia. The southeastern Altay taiga community assemblages appear highly similar to other taiga regions in Siberia but differ considerably from those documented from arid regions.

Tubifera applanata sp. nov. is proposed to validate "Tubulifera applanata" nom. inval. The species diagnosis and some notes on its morphology are provided. At 0.40−0.65 mm diam., individual sporothecae are somewhat larger than in T. ferruginosa and T. microsperma and smaller than those in T. casparyi. Circular ornamentations on the inner peridial surface in T. applanata are larger than previously noted, reaching a size up to 2.9 μm.

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