Key to Danish species of Perichaena Fr.

1 Fruitbodies open irregularly. Sporocarps or elongated plasmodiocarps. P. vermicularis (Schwein.) Rostaf.
1' Fruitbodies open by a distinct lid. Sporocarps, often closely aggregated. 2
2   (1) Sporocarps ± spherical to cushion-shaped. Lid marked as a wavy equatorial line. P. corticalis (Batsch) Rostaf.
2' Sporocarps flattened, closely aggregated and often with angular outline from mutual pressure. Lid marked as a straight line. P. depressa Lib.