Fuscidea aleutica

Fuscidea aleutica is most similar to F. thomsonii, another North American species with a thin thallus, an amyloid medulla, and adnate apothecia. F. aleutica is distinguished by its brown thallus, more sessile apothecia, a better-developed exciple, and darker pigmentation of the exciple and paraphyses; unlike F. thomsonii, it also lacks the pale ring around the inner margin of the apothecia. Although Fryday noted that the two species are very close and may even prove to be environmentally modified forms of a single taxon, he retained them as distinct because they remain separate where they grow together.^[4] Fuscidea aleutica also differs from F. lowensis, which has a thicker areolate thallus and convex, immarginate apothecia, and from F. submollis, which has a thicker thallus, apothecia about twice as large, shorter asci, and somewhat narrower ascospores.^[4][5]

Fuscidea aleutica is a rock-dwelling coastal species of northwestern North America. Fryday reported it from the type collection on Unalaska Island in the Aleutian Islands of Alaska and from three collections on Haida Gwaii, and suggested that it is probably more widespread along the northwestern coast than records indicate. The British Columbia material was collected on rocks in maritime settings, including shoreline boulders, exposed cliffs, and rocks beside a stream, indicating that the species occupies coastal rocky habitats.^[4]