Summary:
Features include 1) resupinate growth on conifer wood and hardwood, less often on other substrates, 2) a white to light brown fruitbody that is thin, easily detached, cobwebby, smooth or minutely granular, the margin fibrillose to rhizomorphic, 3) spores that are nearly round to irregular, with warts, inamyloid, and colorless, 4) a monomitic hyphal system, the hyphae with clamp connections, frequently inflated near septa, often with needle-like crystals present. The name Grandinia microspora P. Karst. has been applied to at least two fungi. In Liberta(1), Liberta, having seen a lectotype specimen, described the spores as having "irregularly scattered obtuse warts". However, the drawing in Hjortstam(6) seems to have much smaller ornamentation on the spore wall than the warts described by Liberta and may be a second fungus, (Ginns), (note also that rhizomorphs are mentioned in the Hjortstam(6) description but not the Liberta(1) description).

Microscopic:
SPORES 4-4.5(5) x (3)3.3-3.5 microns including ornamentation, nearly round to lacrymoid [teardrop-shaped], with a prominent apicular region, verrucose except in apicular region; BASIDIA 4-spored, 9-11 x 4-5 microns, cylindric, with basal clamp connection; HYPHAE monomitic; subhymenial hyphae "short-celled, richly branched, of even width or slightly inflated", 2-4(5) microns wide; subicular hyphae and hyphae of cordons 1.5-2.5(3.5) microns wide, straight, thin-walled, "frequently with ampullate septa, provided with acerose crystals", (Hjortstam), SPORES 3-3.5 x 2-2.5 microns, "appearing irregularly ovoid or oblong as a result of the irregularly scattered obtuse warts", inamyloid, colorless, thin-walled; BASIDIA 4-spored, "at first ovate or oblong, becoming clavate or subcylindrical and slightly constricted in the middle to short clavate", (7)8-12 x 4-5 microns, sterigmata 3.5-5.5 microns long, arcuate; HYPHAE monomitic, CONTEXT HYPHAE (1.5)2-3(3.5) microns, colorless, thin-walled, "with frequent ampulliform swellings at the clamp connection" or short-celled segments up to 7 microns in diameter, "occasionally encrusted with irregularly shaped or lanceolate crystalline material", (Liberta), SPORES 3-3.5 x 2.5-3 microns, nearly round, with irregularly distributed blunt warts, inamyloid, colorless, with 1 droplet; BASIDIA 2-4-spored, 9-15 x 3.5-5 microns, cylindric to clavate; HYPHAE monomitic, 1.5-2.5 microns wide, colorless, septa with clamp connections, sometimes rather thickened at the septa, (Breitenbach)

Notes:
Trechispora microspora has been found in BC, ON, PQ, CO, OH, PA, RI, (Ginns). Distribution includes Idaho, Manitoba, California, New York, Czechoslovakia, Denmark, Estonia, Sweden, and the United Kingdom, (Liberta), Denmark, and Sweden, (Hjortstam), and Switzerland and Asia, (Breitenbach).