Three new cleistocarpous species of the genera Tortula and Microbryum (Pottiaceae, Bryophyta)
Authors: Otnyukova T. N. 
Published: November 2020

Three new cleistocarpous species belonging to the genera Tortula and Microbryum were found among specimens in herbaria LE and MHA identified as Pterygoneurum kozlovii (redefined as Pterygoneurum sibiricum), Tortula acaulon, Microbryum vlassovii and Microbryum curvicollum. The new species Tortula arenaria found in collections from the Republic of Dagestan is similar to M. curvicollum in having curved costa but differs in large and roughly papillose spores (vs. smal ler and smooth in M. curvicollum), branched papillae (vs. simple papillae in M. curvicollum). The new species Microbryum lydiae found in collections from the Republic of Armenia is similar to M. vlassovii in having ventral outgrowths of costa presented as elongated parenchymatous cells but differs in long-mammillose leaf lamina and costa cells (long-mammillose-papillose in M. vlassovii); smaller, warty papillose spores (vs. larger, streaky papillose in M. vlassovii). The new species Tortula irinae is similar to cleistocarpous species of the genus Pterygoneurum in having ventral outgrowths of costa, but differs in outgrowths presented as a pad of large, elongated parenchymatous cells (vs. as low lamellae of several rows of small cells in height in P. kozlovii and high lamellae in P. sibiricum). By ventral outgrowths of costa presented as elongated parenchymatous cells it is also similar to some species of the genus Microbryum, from which it differs in leaf lamina and costa cells with several branched papillae (vs. long-mammillose-papillose leaf lamina and costa cells with one branched papilla in M. vlassovii and long-mammillose leaf lamina and costa cells with one large mammilla in M. lydiae). Tortula irinae resembles T. acaulon in having cleistocarpous immersed capsule. Tortula acaulon is a highly variable species represented by several morphotypes of uncertain taxonomic status but strongly differing in many characters of sporophytes and gametophytes. The most important diagnostic characters are the degree of papillae expression and the shape of leaf and costa papillae. By the degree of papillae expression and the shape of papillae, several morphotypes of T. acaulon were revealed: 1 – morphotype without papillae, 2 – morphotype with simple papillae, 3 – morphotype with branched papillae. Tortula irinae differs from T. acaulon morphotypes in having ventral outgrowths of costa lacking in T. acaulon morphotypes. How ever, of all T. acaulon morphotypes studied, T. irinae can be most probably confused with T. acaulon “branched papillae morphotype” in having strongly branched papillae of costa and leaf cells but easily differing in shape of ventral costa cells protruding as a pad of large, elongated parenchymatous cells in T. irinae vs. ventral costa cells smaller, not protruding in T. acaulon “branched papillae morphotype”. Tortula irinae is widespread in Asian part of Russia [Chukotka Autonomous Area, Republic of Sakha (Yakutia), Trans-Baikal Territory]. It was also found in kept in LE moss collections from Asia (Khazakhtan, Mongolia) and Europe (Ukraine).