Galapagos Species Database

Thallus thin, inconspicuous, almost entirely embedded in the substrate, of the same color as the substrate or slightly darker, more yellowish orange; surface smooth, not pruinose, corticate; Apothecia fissurate, i.e., forming thin, sparsely branched slits; labia inconspicuous or absent, surrounded by a papery thin, ±tiled thallus layer, often with a fine white pruina inside (dumasti-type sensu Staiger 2002); disc hidden, slit-like, immersed, grayish black, ±covered by farinose whitish pruina; exciple thin, not carbonized, pale brown at the apices; hymenium hyaline, clear (not inspers), I–; ascospores hyaline, I+ violet, 6-8 per ascus, ellipsoid to broadly oblong, 20-34 x 11-17 µm, muriform, 5-8 vs. 2-4 celled. Chemistry: No substances found; all spot tests negative.

Fissurina columbina is superficially similar to Phaeophyscia striata but can reliably be distinguished by its muriform, unpigmented, I+ strongly violet spores.