Thallus: squamulose, often forming small cushions squamules: up to 1.5 mm diam., concave or plane, brittle, ascending from the base upper surface: light green to light brown, epruinose upper cortex: poorly developed, containing crystals which are, at least partly, not dissolving in K medulla: lacking algal layer: forming major part of squamule, consisting of algal colonies interspersed by strands of chondroid hyphae, containing crystals which are, at least partly, not dissolving in K, I- lower cortex: similar to upper cortex lower surface: pale brown to white; rhizines: absent hypothallus: absent; vegetative diaspores: absent Apothecia: up to 1 mm diam., constricted at the base, sometimes substipitate, plane and marginate when young, sometimes becoming convex and immarginate, medium brown to brownish black, pruinose ascospores: ellipsoid, 1-septate, hyaline 9-11 x 4-4.5 µm Pycnidia: immersed conidia: shortly bacilliform, 2.5-3 x c. 1 µm Spot tests: K-, C-, KC-, P+ orange Secondary metabolites: pannarin, zeorin, and undetermined secondary products. Substrate and ecology: on soil in open habitats, in Vizcaino subdivision of Sonoran desert and in Californian coastal scrub, up to 500 m World and Sonoran distribution: California and Baja California, rare. Notes: Solenopsora cladonioides has upright squamules that are reminiscent of basal Cladonia squamules. Furthermore, its algal layer forms a major portion of the squamules and is inspersed with strands of chondroid hyphae. Its medulla is more clearly defined than in other Solenopsora species.