Summary: Features include minute, whitish cups that are pruinose on the disc and downy on the exterior, growth on pyrenomycetes, and microscopic characters including branching paraphyses.
Microscopic: spores (13.9)14.6-20.5(22.0) x 3.7-5.1 microns, "often slightly curved, shorter at the ascus apex, longer toward base of ascus", aseptate at first, soon 3-septate (evident in KOH-phloxine-glycerine or lactic acid - cotton blue, but many authors have failed to see septa); asci (78)80-110 x (8.0)8.8-10.2(11.0) microns, with pore blue in Melzer''s reagent; paraphyses filiform but apically deformed and propoloid, (Korf), spores 15-21 x 4-4.5 microns, elliptic-fusiform, sometimes slightly bent, smooth, colorless, usually with 4 droplets, biseriate, sometimes with indistinct septum; asci 8-spored, 105-120 x 11 microns, positive reaction in iodine; paraphyses filiform, cylindric, and strongly forked at tips, (Breitenbach)
Notes: Polydesmia pruinosa is found in BC, WA, and also NY, PA, TN, Canary Islands, and Madeira; it is common and widespread in the United Kingdom and Europe on many different pyrenomycetes; it can be common in the Pacific Northwest, but is rarely collected, (Korf).
Habitat and Range
Habitat
often confluent, on different pyrenomycetes, (Korf), single to cespitose or crowded together, growing on Sphaeriales on dead branches, (Breitenbach)