Varicellaria hemisphaerica

Thallus medium to thick, forming extended, conspicuous patches, pale bluish grey; prothallus distinct, zoned, white; upper surface smooth or uneven to warted; soralia 1– 2 mm diam., markedly convex, often becoming confluent; soredia granular, pale to concolorous, 40–100 μm diam. Apothecia unknown. Soralia C+ carmine-red, K–, KC+ red, Pd–, UV± glaucous (lecanoric acid, unidentified substance).

The pale bluish-grey tinged thallus with an often broad white zoned margin and conspicuous paler or concolorous convex soralia, C+ carmine-red, UV± glaucous, are distinctive features. Ochrolechia subviridis has a darker green to grey-white thallus, C+ orange-red, K–, Pd– and has less delimited or ± confluent, granular- pseudo-isidiate soralia. When growing on rocks V. hemisphaerica resembles V. lactea in which the soralia are also C+ carmine-red but which has a white, regularly rimose-cracked thallus and only slightly convex, pure white and discrete soralia. Loxospora elatina has a thallus that is K+ immediately bright yellow, soft soralia, which contrast more in colour with the thalllus and prefers damp acid bark.