B. crispa B. fecunda B. furfureola B. novozelandica Blennothallia is a genus of jelly lichens in the family Collemataceae.

[3] The genus corresponds to the Colema crispum species group recognized in 1954 by Gunnar Degelius.

[4] Molecular phylogenetic analysis shows that Blennothallia forms a well-supported lineage together with Scytinium and Lethagrium in the family Collemataceae.

[3] Blennothallia species have a dark olive-green to black thallus that typically measures 2–5 cm (0.8–2.0 in) in diameter, comprising rounded lobes that are 0.5 mm (0.02 in) wide.

The thallus lacks a cortex, and the medulla is paraplectenchymatous (fungal tissue with a cellular structure superficially like the parenchyma of vascular plants).