Orthodontiaceae. Genus Orthodontium

1. Leaves unbordered; peristome double, with thin exostome teeth and endostomial segments; western part of European Russia (currently known only from Kaliningrad Province) 1. O. lineare

One of the very few examples of an alien invasive moss species in the Northern Hemisphere. Indigeneous to the Southern Hemisphere, O. lineare was introduced into Europe (initially England) at the beginning of the 20th century and has subsequently been found in many northern and central European countries. In 1990 it was first recorded in Kaliningrad Province as new to Russia. It remains a rare species there, apparently without the ability to spread further eastwards. The species grows on rotten logs, tree bases and decayed litter in pine plantations. It can be recognized by its straight, elongate capsules and delicate peristome of narrow teeth and segments.

Leaves bordered with linear cells; exostome teeth absent and peristome elements formed from delicate and fragile endostomial segments with partially adherent exostomial material; mountains in the southern regions of Siberia and Russian Far East 2. O. lignicola

This species is known from China (Sichuan, Yunnan), Mongolia (Hubsugul area), India (Sikkim), Nepal and from South Siberia from the Altai to Khabarovsk territories. It occurs in the mountains in a narrow altitudinal belt a little below the tree line, where fallen trunks of Larix and Pinus sibirica decay quite slowly due to the cold environment and snow is occasional in summertime. Orthodontium lignicola prefers overhangs of logs and hollows in wood from root side. It is a very rare species in protected areas, while outside of them even moderate human impact reduces the abundance of substrates. Intentional searching in many apparently suitable locations was not successful.