Splachnaceae. Genus Tetraplodon

1.Upper leaf margins with large teeth; capsules emergent 1. T. angustatus

In most territory of Russia this species as widespread as T. mnioides, and they often occur in one tuft. In recent decades it was found in boreal forest of the Middle European Russia, in more southern areas, putatively expanding southwords, and simultaneously it was discovered in the Caucasus for the first time. Serrate margin is sufficient to recognize sterile plants.

Upper leaf margins entire; capsules long-exserted 2

2.Capsules cleistocarpous, pale 5. T. paradoxus

Tetraplodon paradoxusis mainly an Arctic species that occurs on the Arctic Ocean islands, in continental Arctic regions and southwards into the open northern taiga of permafrost areas (e.g., along the Verkhoyansky Mt. System in Yakutia). It was also collected by L.V. Bardunov in the Khemchik Mt. Range of southern Krasnoyarsk Territory near the border with Tyva Republic. This species occurs in the northern areas of North America (Alaska, northern Canada, Greenland); in Europe outside Russia it is known only from the northern parts of Scandinavia and on Svalbard. Tetraplodon paradoxus grows on reindeer dung. Although it sometimes apears to grows directly on soil in the tundra, probably the soil has been fertilized by dung.

Capsules stegocarpous, intensively colored (rarely pale) 3

3.Plants in very dense tufts; setae shorter than 1 cm long; capsules usually very dark red-violet; costae ending before subula; upper leaf cells thick-walled 2. T. urceolatus

In Russia this species is found in the Asian Arctic regions in relatively dry tundras and Siberian mountains. There is also one historical record of it from the Caucasus. When exposed to severe climatic conditions, T. mnioides sometimes forms low, dense tufts that can be difficult to distinguish from T. urceolatus. But, T. urceolatushas bright yellow setae that strongly contrast to the red setae in T. mnioides.

<> Plants in moderately dense tufts; setae 13 cm long; capsules dark red-brown or pale yellow to stramineous; costae ending in subula; upper leaf cells thin-walled 4

4.Capsules pale yellow to stramineous with delicate exothecial cell walls, capsule mouths after dehiscence quadrate; hypophyses as wide as urns; rare northern species (although locally common in Yakutia reindeer pastures) 4. T. pallidus

This species occurs in areas of intensive reindeer farming in the northern regions of Siberia. Tetraplodon paradoxus has somewhat similar pale capsules; however, it differs in having longer setae, smaller, lighter colored opercula, and cleistocarpous capsules. However, the best way to separate the two species is by the presence in T. pallidus of stegocarpous capsules with quadrate mouths.

<> Capsules dark red-brown with firm exothecial cell walls, capsule mouths after dehiscence round, hypophyses wider than urns; common in the Russian Arctic and northern boreal zone 3. T. mnioides

This is the most common species of Splachnaceae in Russia. It occurs throughout Siberia, but in European Russia it is known only from the northern boreal zone. It grows on various types of dung and rotting animals. Often the animals are so strongly decomposed that it is not possible to identify the substrate. Tetraplodon mnioides often grows mixed with T. angustatus, but not with the more xerophytic T. urceolatus.