Abstract
Odontoschisma sphagni is reported from the Kaliningrad Province, West Russia. This is the first documented report of the species from the territory of Russia. Complete morphological description, ecological and geographical characteristics, key to the species of Odontoschisma, known from Russia, and distinctions from morphologically similar, when sterile, Jamesoniella autumnalis and J. undulifolia are provided. Differentiation of Russian species of Odontoschisma is considered. The strong overlap of variability of O. elongatum and O. denudatum, absence of reliable distinctions, except different pigmentation of plants and the middle lamellae, unstable distinctions in cuticle and asexual reproduction patterns, and vicarious distribution form a basis to distinguish O. elongatum as a subspecies O. denudatum subsp. elongatum (Lindb.) Potemkin comb. et stat. nov.