[5] Ove Eriksson challenged Henssen's classification of Pyrenothrix in 1981, proposing instead that it was closely related to the sooty molds, specifically the family Coccodiniaceae.

These hyphae are branched and interconnected, consisting of elongated, often curved cells that are pale brownish in colour and sometimes inflated at the ends.

[3] In terms of reproduction, the sexual morph of Pyrenotrichaceae is characterised by perithecioid ascomata, which are spore-producing structures that are either sessile (attached directly by the base) or immersed among the thallus filaments.

The ascospores produced by the asci typically number eight per ascus and have a transversal septate to muriform (divided into compartments) structure, with a colour ranging from pale to dark grayish-brown.

[3] The asexual morph of Pyrenotrichaceae, which refers to the part of the life cycle where reproduction does not involve the fusion of gametes, remains undetermined.