Thallus: crustose, warted-areolate or minutely squamulose, mostly sorediate, rarely esorediate areoles: regular in outline or irregularly incised, 0.1-0.4(-0.6) mm in diam., usually strongly convex surface: grayish green to sordid olive-green, dull upper cortex: poorly developed, 5-10(30) µm high, with hyaline or brownish hyphae; algal layer: 45-150(-300) µm high medulla: 25-175 µm high, sometimes lacking soralia: punctiform, often in the center of single areoles, rarely confluent, usually darker or of same color as esorediate thallus parts, 0.1-0.5 mm in diam. photobiont: 4-8(-10) µm in diam. Apothecia: relatively rare, ±flexuose in outline, rarely rounded, sessile with a constricted base, 0.3-0.7(-1) mm in diam disc: black, sometimes with a bluish or greenish tinge, dull, epruinose, flat margin: prominent when young, persistent but ±level with disc in old apothecia, dull exciple: laterally 20-50 µm, basally 25-105 µm wide, appearing pseudoparenchymatous, composed of densely entangled, brown, short-celled hyphae with lumina 1-3 µm wide; epihymenium: 10-25 µm high, sordid olive-brown hymenium: hyaline, rarely pale brown, 40-50 µm tall; paraphyses: hyaline, moderately to strongly branched and anastomosing, sometimes with brownish apical cells, lumina 1-1.5 µm, apically 1-2 µm wide; subhymenium: 40-60 µm high; hypothecium: hyaline or pale ochre, 20-100 µm high asci: clavate, 8-spored ascospores: hyaline, simple, (5.5-)6.7-9.3-(-11) x (2.5-)3.2-4.1(-4.5) µm Pycnidia: globular, immersed, 75-125 µm in diam.; wall: hyaline to pale brown conidia: bacilliform, 5.5-7 x 0.5-1 µm Spot tests: thallus K-, C+ red, KC+ red, P-, UV- Secondary metabolites: gyrophoric acid. Substrate and ecology: usually on hard wood, rarely on conifer or hardwood bark or charred wood World distribution: more or less cosmopolitan Sonoran distribution: in oak and conifer forests of Arizona, southern California, Sonora and Chihuahua at 300-2700 m. Notes: Fertile collections of T. flexuosa and T. granulosa can easily be distinguished by the differing spore size, but sterile collections may be difficult to tell apart. Trapeliopsis flexuosa usually has a sordid olive green or dark gray thallus and even darker, punctiform soralia, while the thallus in T. granulosa is often light greenish or gray and the soralia are larger, often confluent and paler, usually of the same color or slightly lighter than esorediate thallus parts. Trapeliopsis granulosa is more often found on rather soft substrates, while T. flexuosa is typically on hard bare wood, such as fence posts, shingles, wooden structures, and hard decorticate stumps and logs.