Thallus: foliose or subfruticose, up to 3 cm in diam., usually irregular lobes: elongate and discrete to entangled, 0.5-1(-2) mm broad, usually +flat or terminal segments sometimes almost terete, usually ascending and sometimes turf-like upper surface: pale green-gray to brown, epruinose, without soredia or isidia upper cortex: paraplectenchymatous medulla: white lower cortex: paraplectenchymatous lower surface: white to pale tan, dull, often with a few low, algae-containing warts; rhizines: simple, concolorous with the lower surface or darkening, rather sparse and often mostly on or near the margin Apothecia: rare, up to 1.5 mm in diam., sessile to short stipitate; margin: entire or becoming crenate; corona of rhizines: absent or inconspicuous ascospores: ellipsoid, 17-23 x 7-10 µm, Physcia-type Spot tests: all negative in cortex and medulla (rarely with a yellowish K+ violet pigment in the lower cortex) Secondary metabolites: none detected. Substrate and ecology: soil or mosses on soil or rock World distribution: North America and Europe Sonoran distribution: presently known from just outside the study area, in New Mexico. Notes: The distinctive irregular, almost subfruticose or turf-like habit and its distinctive occurrence on soil together distinguish Phaeophyscia constipata from other Phaeophysciae in the Sonoran region. The only other species with a pale lower surface and lacking soredia and isidia is P. sonorae, which is a more regular orbicular species growing directly on bark or rock. Although not yet known from the study area, P. constipata is easily overlooked and is to be expected from mountainous areas throughout the Sonoran region.