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Pertusaria leioplaca DC.
Family: Pertusariaceae
[Pertusaria leucostoma A. Massal.,  more]
Pertusaria leioplaca image
André Aptroot  
Thallus: continuous to superficially fissured, with thin to very thin verrucae; margins: entire, unzoned upper surface: ash gray to yellow-gray or green-gray, smooth to tuberculate, often shiny, epruinose to slightly pruinose; lacking soredia or isidia fertile verrucae: concolorous with thallus, ampliariate to erect or pertusariate, numerous, c. 0.7-2.5 mm in diam.; ostioles 1-6 per verruca, hyaline Apothecia: (1-) 2-4 (-6) per verruca; epithecium: hyaline, yellowish or dark brown to black-brown; hypothecium: hyaline to yellowish asci: cylindrical, 250-450 x 30-70 µm, (2-) 4-spored ascospores: hyaline, ellipsoid, 40-130 x 25-50 µm; spore wall: 2-layered; outer spore wall: c. 1-7 µm thick; inner spore wall: 2-12 µm thick; apices: up to 28 µm thick Pycnidia: immersed conidia: bacilliform, 7-10 x 0.5-1.0 µm Spot tests: K- or + weakly yellow, C-, KC-, P+ yellow to orange, UV- or + pale orange-pink Secondary metabolites: 4,5-dichlorolichexanthone and stictic acid (both major), constictic acid (minor). Substrate and ecology: on bark, including Abies and Quercus World distribution: pantemperate species in the Northern Hemisphere, in Europe and North America Sonoran distribution: in mountainous areas of southern California at 500-2700 m. Notes: Pertusaria leioplaca is characterized by a light-green thallus, ampliariate or pertusariate verrucae, 4-spored asci, and the presence of 4,5-dichlorolichexanthone and stictic acid. It is hardly confused with any other species in the area, but some poorly developed specimens of P. texana or P. xanthodes may be morphologically similar. They are readily distinguished by the presence of thiophaninic acid (UV+ orange) and a different number of spores per ascus (eight in P. texana and two in P. xanthodes). When the starting point for lichens and fungi was unified, this was one of the few lichen names that had to be changed (Santesson 1993).