Nivicolous myxomycete assemblages were surveyed on the northwest of the Greater Caucasian ridge in May-June 2010 and 2011 at a north facing transect between 1,700 and 2,920 m elevation of the summit Malaya Khatipara situated within the Teberda State Biosphere Reserve. Morphological characters of 396 collections representing 45 taxa (39 species, 3 varieties, and 3 forms) of myxomycetes in 8 genera and 5 families were recorded. Many (13) taxa are classified as rare (a species represents <0.5 % of all records). Only seven species were found to be widely distributed (present in 50 % or more of the 17 studied localities). To confirm the assignment of specimens to morphospecies, we obtained independently from determination 145 partial sequences of the 18S SSU rRNA gene from 35 taxa of Lamproderma, Meriderma, Physarum and Diderma, which turned out to represent 58 genotypes. Most of the taxa represented by more than one sequence had several genotypes, with an average of 1.7 genotypes per taxon. Except for three taxonomically difficult groups of species, partial SSU sequences did well correspond with the respective morphospecies and where similar or identical to sequences of specimens from the European Alps, making this marker a good candidate for barcoding in myxomycetes. Species richness and diversity increased from subalpine crooked-stem birch forests (23 species, 2 varieties, H′ = 2.8, E = 0.88, D = 0.08) to alpine dwarf shrub communities (34 species and 2 varieties, 2 forms, H′ = 3.2, E = 0.89, D = 0.05) but decreased again for alpine meadows (27 species and 2 varieties, 2 forms, H′ = 3.1, E = 0.91, D = 0.06). Species richness and alpha-diversity reached maximum values for ground litter, whereas leaves and stems of living shrubs above ground harboured a more depauperate myxomycete assemblage.

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