Phaeophyscia orbicularis

Diane L. Haughland

Phaeophyscia orbicularis (Neck.) Moberg, 1977

Common name	Mealy Shadow
Code	PHAEORB
Field Characters	Small, narrow-lobed, foliose chlorolichen. Thalli appressed, orbicular, attached throughout, to 3 cm diameter, sometimes forming large, confluent colonies. Lobes typically 0.5-1.5 mm across. Upper cortex grey-brown to dark brown, dull, lacking pruina, hairs, or isidia. Lower cortex black, but may be pale at the lobe tips or on some shaded thalli it may be almost entirely pale. The rhizines tend to be shorter and sparser than in other Phaeophyscia species, black with white tips, simple. Greenish to greyish granular to farinose soredia present in orbicular to irregular, laminal soralia, rarely also terminal or marginal. Medulla white. Apothecia common in urban sites, occasional elsewhere in Alberta. Often parasitized and then with lumpy, laminal darkened outgrowths.
Similar species & genera	Phaeophyscia adiastola: more commonly on rock but also epiphytic, soredia more granular, almost isidia-like and typically terminal and marginal rather than laminal. Physciella melanchra: uniformly pale, longitudinally striate (prosoplectenchymatous) lower cortex (vs. paraplectenchymatous and dark at least centrally in P. orbicularis). To date we have not confirmed that P. melanchra occurs in our region
Ecology	Epiphytic on a variety of host trees and shrubs, occasionally on rocks. Relatively common across all the boreal, foothills, parkland and grasslands, rare in the shield and mountain regions. Very common on urban boulevard trees (Haughland et al. 2022)
Chemistry	All spot tests negative (no substances detected, Esslinger 2004).
Molecular support	Molecular support: limited species-level support (Lohtander et al. 2000), work is required, samples submitted to T. Esslinger and S. Leavitt (unpublished data).
Links	ABMI Biodiversity Browser Consortium of Lichen Herbaria Ways of Enlichenment Photo Gallery
Gallery