Ptychomitriaceae. Genus Brachydontium
1. Peristome present; stems 0.5-1.2(-2) mm long —
1. B. trichodes
Found in Russia in two localities in Kamchatka: in subalpine belt, at 600-850 m a. s. l. , on lithosoil on rocky slope, and on volcanic boulder in Pinus pumila thicket.
Peristome absent; stems 3-7 mm long —
2. B. olympicum
Reported from Paramushir Island, North Kuriles, on volcanic substrate on slope of Ebeko Volcano.