E-Flora BC: Electronic Atlas of the Flora of British Columbia

General:
Common Name: The Specklebelly Lichens. Alludes to the pale specks of pseudocyphellae occurring over the lower surface of the species.
Large stratified foliose lichens, corticate above and below, sorediate or isidiate or not, lobes loosely attached, short to somewhat elongate, averaging to 6–20 (–30) mm wide, thin. Upper surface greyish or brownish, smooth or reticulate. Lower surface tomentose or not, bearing pseudocyphellae, lacking rhizines. Medulla white or occasionally yellow. Photobiont green or blue-green.
Apothecia located over upper surface or along lobe margins, disc brownish (except black when parasitized); spores 2-celled to multi-celled, spindle-shaped, colourless or brown when mature, 8 per ascus.
Over bark.
Notes: Pseudocyphellaria, with approximately 200 species, is primarily a temperate genus of the southern hemisphere. Of the six species reported for North America, five occur in B.C. Spot tests are of little taxonomic value in this genus and have been omitted in the species accounts.

Species description:
Soredia or isidia present AND
Isidia absent; soredia present; medulla white or yellow; upper surface brownish or greyish AND
Soredia and/or pseudocyphellae distinctly yellow; medulla yellow or white AND
Photobiont a dark blue-green cyanobacterium; medulla white to strong yellow (check fresh breaks in upper cortex); upper surface naked, greyish or brownish when wet; lobe margins naked

Comments:
Specimens in which the soredia are confined to the lobe margins are sometimes referred to P. mougeotiana (Del.) Vainio.