Bryostigma is a genus of lichen-forming fungi of uncertain familial placement in the order Arthoniales. The genus was circumscribed in 1979 by Josef Poelt and Peter Döbbeler, with the muscicolous lichen Bryostigma leucodontis assigned as the type species. A dozen Arthonia species were transferred into the genus in 2020 following molecular phylogenetic analysis of the family Arthoniaceae that showed distinct phylogenetic lineages that were basal to that family. The genus contains several parasitic species that occur on hosts having chlorococcoid photobionts (i.e., green algae that have a spherical shape).
, Species Fungorum (in the Catalogue of Life) accepts 15 species of Bryostigma: