Schismatomma species form a thin, crust-like
thallus that lies more or less flush with the bark or rock surface. Where colonies meet they may be separated by a dark brown to black fringe (the ), and some species develop powdery reproductive patches called
soralia that can mask the underlying crust. A quick scratch of fresh material exposes an orange stain—pigment from the filamentous alga
Trentepohlia, which supplies the
photosynthetic partner in every species. Because the crust lacks a true outer skin () the sits immediately beneath the fungal tissue.
Sexual fruit bodies (
apothecia) start embedded in the thallus but often emerge to become small, slightly irregular . Each is ringed by a rim of thallus tissue (), while the fruit body's own wall () remains poorly developed and soon blends into the surrounding crust. Internally, the spore-bearing layer (
hymenium)
stains blue in iodine and is threaded by branched, interwoven filaments (). Beneath lies a dark olive to black that may be scarcely visible in thin specimens. The
asci are club-shaped and split open () to release eight spindle-shaped to gently curved
ascospores, each divided by several
cross-walls; the spores are colourless when young, may brown slightly with age, and can coil inside the ascus before discharge.
Asexual propagation occurs in flask-shaped
pycnidia sunk within the thallus. Their lining cells bud off minute, rod-shaped
conidia—straight, curved, or kidney-shaped—that escape through a tiny pore and disperse independently of the alga. Chemical analysis shows wide variation: different species may contain
orcinol-type
depsides such as
lecanoric acid or
erythrin, β-
orcinol compounds like
fumarprotocetraric or
psoromic acids, yellow
chromones,
fatty acids, or remain chemically undetected.
Morphologically the genus resembles
Enterographa and
Lecanactis, but it is set apart by the presence of a thalline margin around the apothecia and a much reduced exciple. ==Conservation==