Description:
Thallus mostly immersed in the substratum, where present reduced to the immediate vicinity of apothecia and sheltered spots (underside of the rock), creamy-white, smooth, cracked-areolate; epinecral layer often present, 510 m thick; medulla I+ violet. Photobiont chlorococcoid; cells 912 m diam.
Apothecia black, lecideine, 0.81.5(2.0) mm diam., flat, orbicular; disc flat, becoming convex and irregularly fissured when overmature: proper margin thin (0.05 mm wide), barely raised, becoming excluded in mature apothecia, in section poorly developed; pseudothalline margin usually present, thick (up to 0.2 mm wide) appearing pruinose due to thin (510 m thick) epinecral layer. Hymenium 170200 m tall, with large oil globules (1030(40) 10(15) m) in the upper hymenium that dissolve in K; paraphyses 11.5 m wide, branched and anastomosing, with distinctly swollen apices (up to 5 m) and pigmented caps; epihymenium 2550 m tall, dilute brown to olivaceous-brown (K olivaceous or blue-black in patches). Asci cylindrical, c. 100 30 m, Porpidia-type, no mature asci seen; ascospores simple, pigmented, 8 per ascus, 2530 1215 m. Hypothecium hyaline to pale straw coloured.
Conidiomata: not observed.

Chemistry: No substances by TLC.

Distribution and Ecology: Known only from the type collection, which is from an apparently loose, angular piece of crystalline granite from the summit of Mt. Adam on West Falkland. Dactylospora australis Triebel & Hertel occurs on the apothecia of the type collection but no other species are present on the piece of rock. However, other species collected from the vicinity include Lecanora xantholeuca (Mll. Arg.) Hertel, Lithographa graphidioides (Cromb.) Imshaug ex Coppins & Fryday, Micarea incrassata Hedl., Poeltidea pertusa and Thamnolia vermicularis (Sw.) Schaer.

Remarks: In apothecial characters, this species closely resembles the type species of the genus, P. perusta. However, it differs from that species in the lack of a well-developed thallus, and the apothecia with a hymenium containing large oil globules.

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Thallus and apothecia


Hymenium with oil globules