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 present on lobe margins AND
Lobes concave to convex or, if helmet-shaped, then apparently never over oak; spores less than 14 m long, usually 1-septate AND
Lobes appressed to ascending, but rarely erect, averaging to slightly wider than long; soredia C+ red or C- AND
Upper surface never strong brown; apothecia, if present, black; soredia C+ red AND
Lobes larger, usually greenish, somewhat loosely attached (squamulose), averaging to more than 0.8 mm across; over deciduous trees and conifers; soredia K-

Reactions:
Cortex and soredia C+ red, KC+ red.

Contents:
Lecanoric acid.

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 ostreata (Hoffm.) Schaerer
Lecidea scalaris (Ach. ex Lilj.) Ach.
Psora ostreata Hoffm.
Psora scalaris (Ach. ex Lilj.) Hook.