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Peltula impressa (Vain.) Swiscow & Krog
Family: Peltulaceae
[Heppia impressa Vain.]
Peltula impressa image
André Aptroot  
Thallus: squamulose, ± placodioid, overall c. 1-2 cm diam. central squamules: obconical to clavate or cylindrical, convex or flattened at top, 0.2-0.5 mm wide 0.4-0.8 mm long upper surface: olive brown, smooth, not sorediate upper cortex: not developed but with a yellow epinecral layer (6-12 µm thick) marginal squamules: effigurate, sometimes almost ribbon-like medulla: composed of densely interwoven hyphae with globose to elongated cells (2.5-3 µm thick), with an poorly delimited algal layer in the upper part lower cortex: 15-24 µm thick, paraplectenchymatous with globose hyphal cells, 5-8 µm diam. lower surface: paler than the upper surface, Apothecia: 1-2 (-3) per squamule, only occurring on central squamules, immersed; disc: red-brown to black, usually expanded (0.1-0.3 mm in diam.); epihymenium: red-brown to black; hymenium: I+ wine-red or weakly blue, 170-250 µm high asci: clavate to obclavate; wall: I+ red-brown but blue after pretreatment with K, >64-spored ascospores: globose to ellipsoid, 3.5-5 (-7) x 2.4-3.5 (-4) µm Pycnidia: only one immature seen, spherical conidia: not known Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: mainly on acidic rocks in deserts and other open, arid habitats World distribution: SW North America, Australasia, southern and East Africa Sonoran distribution: desert areas of Sonora and Baja California Sur.