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Metamelanea melambola (Tuck.) Henssen (redirected from: Pyrenopsis melambola)
Family: Lichinaceae
[Pyrenopsis melambola (Tuck.) Tuck.,  more]
Metamelanea melambola image
André Aptroot  
Thallus: crustose, rimose-areolate to areolate-squamulose areoles: 0.5-2 mm wide, up to 0.8 mm thick, ±angular, composed of numerous, densely aggregated, erect 'lobules' (0.02-0.04 mm wide) upper surface: usually black, sometimes dark reddish brown on acidic rocks, rough anatomy: densely reticulate lower surface: attached by tufts of rhizohyphae Apothecia: immersed, 1(2-3) per areole but hymenium becoming multiply divided, 0.5(-0.75) mm wide; thalline margin: indistinct, persisting, rough, often separated from the proper exciple by a slit disc: black, rough, finally becoming umbonate proper exciple: thin but distinct, brownish black colored, K± dirty purple epihymenium: brownish black, K± dirty purple hymenium: hyaline, up to 150 µm high, IKI+ blue; hypothecium: hyaline or ±pale brown, IKI+ blue ascus: cylindrical or narrow clavate, 8-spored ascospores: simple, hyaline, broad ellipsoid, (7.5-)9.5-12 x (5-)6-7 µm, thin-walled Pycnidia: not observed Spot tests: all negative Secondary products: none detected. Substrate and ecology: on acidic rocks, in rocky slopes or seepage tracks World distribution: North America, Venezuela, and southern Yemen Sonoran distribution: a single locality on schist in northern Arizona. Notes: Metamelanea melambola is characterized by immersed apothecia with a rough to umbonate disc and a finally multiply divided hymenium. The upper parts of the hymenium and the proper exciple are dark brown, an unusual feature in otherwise similar crustose species of Psorotichia, Lemmopsis, and Pyrenopsis. Furthermore, the areoles are composed of vertically growing, densely packed "lobules", that are similarly known from Stromatella bermudana. The latter species, however, differs in the finely tessellate thallus surface, its pale yellow coloration of the epihymenium and proper exciple and its occurrence on limestone. The Californian specimens named "Pyrenopsis melambola" in the Hasse exsiccate belong to different crustose members of the Lichinaceae.