Thallus: crustose, thick, consisting of dispersed or contiguous verrucae, up to 0.4-0.6 mm wide surface: light to dark gray, dull; margin: determinate; prothallus: sometimes present, dark, fimbriate; vegetative propagules: absent Apothecia: sessile, frequent, contiguous or not, up to 0.61 mm in diam. disc: dark brown to black, concave at first, becoming plane thalline margin: concolorous with thallus, prominent, 0.1-0.15 mm wide, entire and persistent; excipular ring: absent thalline exciple: 60-110 µm wide laterally; cortex: 10-20 µm; cells: up to 4.5-5.5 µm wide, not pigmented; algal cells: up to 11.5-15.5 µm in diam.; thalline exciple: 90-140 µm below; cortex: 20-40 µm wide, cellular proper exciple: hyaline, 10-15 µm wide laterally, expanded to (10-)20-30 µm at periphery hymenium: 120140 µm tall; paraphyses: 2.5-3 µm wide, often conglutinate, sometimes with oil paraphyses, with apices lightly pigmented, up to 4-7 µm wide, immersed in dispersed pigment, forming orange-brown epihymenium; hypothecium: hyaline, 50-80 µm thick asci: clavate, 70-80 x 22-25 µm, 8-spored ascospores: brown, 1-septate, broadly ellipsoid, type A development, Pachysporaria-type, (18.9-)22.5-24(-28) x (10.5-) 13-14(-16.5) µm, lumina irregularly polygonal when immature, lumina often developing satellite apical lumina, more rarely additional lateral lumina, spores persistently thick walled, often slightly waisted at maturity; torus: narrow; walls: not ornamented Pycnidia: prominent, dark brown to black, 0.05-0.1 mm in diam., on small verrucae; conidiophores: type I conidia: bacilliform, 3.5-4.5 x c. 1 µm Spot tests: K+ yellow, C-, KC-, P+ lemon yellow (rarely P+ red) Secondary metabolites: atranorin, zeorin and unknown substance 3-4/4-5/3 (or stictic acid replacing unknown). Substrate and ecology: on siliceous rock and rhyolite World distribution: endemic to southwestern North America Sonoran distribution: southern Arizona and Chihuahua, at elevations of 1700-2560 m. Notes: Rinodina verruciformis is characterized by its rock growing habit and large, Pachysporaria-type spores with small, apical, satellite lumina, and by its chemistry. The polygonal shape of the immature spore lumina indicate a relationship to R. algarvensis Giralt, Barbero & v.d. Boom (1996), another species on rock described from maritime southern Portugal. This latter species, however, lacks satellite apical spore lumina, and is sorediate, possessing discrete soralia.