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Arthoniaceae
Arthonia radiata Growth type crustose Chemical results negative. Epithecium brown or olive-brown, K+ pale green Pioneer species, very common on smooth-barked trees and shrubs. Sometimes host to Muellerella polyspora, Stigmidium arthoniae, spores 17-23 x 4-5 µm, 1(-3) septate and Opegrapha arthoniicola, the spores 3-septate (10.5-)12.5-14.5 x 3.4-4.2(-4.8) µm. The small patches of white, pale-grey or olive-brownish thallus are often surrounded by a black prothallus. Crowded, black, rounded or star-shaped apothecia are not pruinose. Asci are 8-spored, the spores 3-septate, upper cell not enlarged, 15-20 x 5-7 µm. Micrographs below. Similar: Coniocarpon cuspidans (Arthonia elegans). Thallus often tinged yellowish, apothecia K+ red-purple, |
