R. callibotrys R. ceranisca R. coccophylla R. effusa R. laevispora R. multipunctata R. occultata R. pallida R. populina Rostania is a genus of lichen-forming fungi in the family Collemataceae.

The genus is characterized morphologically by having minute thalli made of hyphal tissue without a separate cortex, and the more or less cuboid-shaped ascospores.

[4] In its new, restricted sense, following its revision using molecular phylogenetics and subsequent resurrection,[5] Rostania is equivalent to the Collema occultatum group as defined by Gunnar Degelius in 1954.

[6] The taxonomy of the non-monophyletic taxon Rostania occultata is recently been clarified, and revised generic limitations of the genus proposed, such that some species have been excluded and transferred to other genera.

These lichens exhibit dark olive green, black, or brownish colours and can either form a diffuse granular crust or have poorly developed lobes up to 1 or 2 mm wide.

The medulla consists of hyphal structures intermingled with chains of Nostoc photobiont cells; a tomentum is absent in Rostania species.