General:
Common Name: The Turtle Lichens. Describes the shell-like habit of the species. Minute stratified squamulose lichens, corticate above, corticate or not below, sorediate or not, squamules closely appressed or more often attached to substrate at one margin, the opposite margin weakly raised, short to subrotund, averaging to 0.8–1.5 (–2) mm wide, thin. Upper surface pale greyish, greenish or dark brown, shiny or not. Lower surface pale or darkening, lacking rhizines. Medulla white. Photobiont green.
Apothecia usually located along lobe margins, disc plane or occasionally convex, brown orblack; spores simple, ellipsoid to spindle-shaped, colourless, 8 per ascus.
Over (fire-blackened) trees.
Notes: Hypocenomyce is primarily a temperate and boreal genus consisting of ten species worldwide. Of the eight species reported for North America, four are known to occur in B.C. Hypocenomyce was formerly treated within Psora. The taxonomy of the western North American species has not been entirely elucidated; this treatment is preliminary, pending further study.

Species description:
Soredia absent AND
Lobes strongly lobulate, lobules in part distinctly longer than broad; upper surface never strong brown; apothecia abundant or absent, disc black AND
Upper surface pale greenish, larger; lobes averaging to more than 0.5 mm long; over old conifers in humid climates throughout

Reactions:
All spot tests negative, but medulla UV+ white.

Contents:
A single unknown UV+ compound.

Source:  Lichens of British Columbia

If more than one illustration is available for a species (e.g., separate illustrations were provided for two subspecies) then links to the separate images will be provided below. Note that individual subspecies or varietal illustrations are not always available.

Illustration By:  Trevor Goward

Synonyms and Alternate Names:
Lecidea friesii Ach.
Psora friesii (Ach.) Hellbom