Fedosov, V.E., E.A. Ignatova, A.V. Fedorova & J. Kučera. 2021. Microamblystegium – a new genus of Amblystegiaceae from Shikotan Island (South Kurils, Russian Far East)

Arctoa (2021) 30: 417–424

doi: 10.15298/arctoa.30.27

A molecular phylogenetic study based on the plastid trnL-trnF, atpB-rbcL and nuclear ITS sequences resolved an unnamed tiny saxicolous moss recently collected in Shikotan Island in a clade with Kandaea, Palustriella and Cratoneuron. At the same time, it markedly differs from them morphologically in having homogeneous stem cross section, weak single costa reaching only 0.3 to 0.7 of leaf length, and very weakly differentiated alar cells. The moss is therefore described here as Microamblystegium saxicola gen. and sp. nov. We speculate that it represents another specialized evolutionary lineage with miniaturized and simplified morphology likely associated with adaptation to growth in shaded cliff niches, matching a similar pattern observed in the recently described amblystegiaceous genus Arvernella. Such specialized lineages of minute saxicolous mosses remain poorly known due to their outstanding rarity.