E-Flora BC: Electronic Atlas of the Flora of British Columbia

General:
Common Name: The Stippleback Lichens. Emphasizes the presence of numerous dot-like perithecia over the upper surface.
Small to medium stratified foliose lichens, corticate above and below, lacking isidia and soredia, lobes attached to substrate by more or less central holdfast (except occasionally unattached in some species), loosely attached, subrotund to rotund, entire thallus averaging to 1–3 (–6) cm across, usually somewhat thick. Upper surface greyish to dark olive brownish. Lower surface pale brown or blackening, rhizinate or more often lacking rhizines. Medulla white. Photobiont green.
Ascocarp a perithecium immersed in upper surface, appearing as blackish dot from above; spores simple, ellipsoid, colourless, 8 per ascus.
Over rock, rarely over exposed soil.
As adopted here, Dermatocarpon includes all foliose or squamulose peritheciate lichens having simple spores and attached to substrate by one or more thickened holdfasts, whether central or marginal. Squamulose specimens attached by rhizoidal threads are treated under Catapyrenium.
Notes: Dermatocarpon is a cosmopolitan genus of approximately 60 species. Only seven species are reported for North America and five occur in B.C. This is a taxonomically difficult group in which many species appear to intergrade. The keys should be considered preliminary, pending a thorough taxonomic revision of the genus. Chemistry is of no diagnostic value in Dermatocarpon and has therefore been omitted in the following species accounts.

Species description:
Thallus lobes averaging to more than 6 mm across, or if smaller, then upper surface greyish and strongly white-pruinose; upper surface KC-; spores at most 8 per ascus AND
Rhizines absent AND
Upper surface white-pruinose or not; lower surface varying from smooth to wrinkled or irregularly granular; granules, if present, roughly spheroidal and averaging to more than 0.2 mm across AND
Upper surface in part heavily white-pruinose; never turning bright green when wetted; confined to dry/xeric sites AND
Thallus single-lobed/monophyllous to rarely many-lobed/polyphyllous; central lobes absent or, if present and dense, then concave to more often plane, never appearing chinky-cracked/areolate from above, margins usually upturned or at least not strongly downturned

Comments:
Like D. Reticulatum, with which it appears to intergrade, D. miniatum may adopt an unattached/vagant habit in highly exposed inland sites. The material is apparently heterogeneous and may include two species:
1.Over base-rich rock; lower surface tan, brown or orangish brown, more or less smooth - Dermatocarpon miniatum
2. Over base-poor rock (e.g., basalt); lower surface dark brown to black, strongly and broadly wrinkled - Dermatocarpon sp. 1