Ignatov, M.S., E.A. Ignatova & O.I. Kuznetsova. 2021. A rare European endemic moss genus Arvernella is discovered in Sakhalin, Russian Far East, where it is also rare

Arctoa (2021) 30: 1–7

doi: 10.15298/arctoa.30.01

A molecular phylogenetic analysis revealed that a tiny Amblystegiaceae plant from Sakhalin in the Russian Far East is most closely related to the recently described European endemic genus and species Arvernella microclada. This species is one of the smallest pleurocarpous mosses and it remains known only from a limited area in France, 9000 km from Sakhalin. Sakhalin plant differs from European in longer leaf costa and almost smooth laminal cells versus distinctly prorate in A. microclada, in addition to genetic differences. An equally small East Asian Platydictya fauriei, known from Japan and Corea, differs from the Sakhalin plant in its narrow laminal cells (4–6:1 vs. 1.5–2.5:1). Thus, this Sakhalin plant is described as a new species, Arvernella pisarenkoi Ignatov & Ignatova.