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Arctomia interfixa (Nyl.) Vainio
Family: Arctomiaceae
Arctomia interfixa image
Thompson, J., 1984. American Arctic Lichens: The Macrolichens.
Thallus forming small rosettes or dispersed, the lobes 0.2-0.6 mm broad, somewhat imbricated in the rosette forms, rust-brown; cortex brown.

Cortex not as well defined as in A. delicatula; medullary hyphae 5-11 u thick, or irregularly grouped ellipsoid or spherical cells.

Apothecia red-brown, convex, to 0.5 mm broad; hymenium 70-110 ¡x\ subhymenium BO-245 /x, paraphyses 1-2 fx, the tips capitate, 4-8 fx, and brown; asci 50-90x8-21 ¡x\ spores 8, 4-7 celled, spindle-shaped 26-46 x 3.5-6 /X.

This species grows over mosses and other lichens. It is undoubtedly circumpolar in distribution. It has been reported from Siberia, Norway, Sweden, Finland, Novaya Zemlya, Spitzbergen, and Bear Island. It appears to be rarely found in North America, specimens being known from Baffin Island, N.W.T., and the Olympic Mountains in Washington.