Summary: Features include flat growth on dead aspen with pores exposed, a bright lemon yellow color, and microscopic characters. This variety may not be distinct from the type variety. The description is derived from Gilbertson(1) for var. pulchella.
Microscopic: spores 6-7.5 x 4-5 microns, elliptic, some truncate, smooth, inamyloid, colorless, thin-walled; basidia 4-spored, 15-20 x 7-8 microns, clavate, with basal clamp; cystidia none, cystidioles not projecting, 15-17 x 4-6 microns, fusoid, with basal clamp; hyphal system dimitic: subiculum generative hyphae 2-3 microns wide, thin-walled, with clamp connections, subiculum skeletal hyphae 2-4 microns, "thick-walled, nonseptate, some often branched"
Notes: Perenniporia tenuis var. pulchella has been found in BC, WA, OR, ID, AB, NWT, YT, AK, AZ, CA, CO, MT, NM, UT, and WY, (Gilbertson).
Habitat and Range
SIMILAR SPECIES
Perenniporia tenuis var. tenuis is differentiated by its cream color and has been found in southeastern North America, AZ, CO, MT, and NY. Perenniporia medulla-panis can be bright yellow: pores are 5-7 per mm, skeletal and binding hyphae are dextrinoid, and spores are thick-walled and dextrinoid, whereas P. tenuis var. pulchella has pores 4-5 per mm, spores are thin-walled and not dextrinoid, and hyphae are not dextrinoid, (Ginns). Perenniporia narymica can be bright yellow: pores are 3-5 per mm, neither hyphae nor spore walls are dextrinoid, and the hyphal system is dimitic, (Ginns).
Habitat
annual, on dead fallen aspen, rarely on other substrates, causes white rot of dead hardwoods and conifers