Summary: Sistotrema binucleosporum is a member of the Sistotrema brinkmannii group, described as follows, "Fruitbodies effuse, smooth or grandinioid; hyphae with clamps, walls hyaline; gloeocystidia absent; basidia urniform, normally with 6-8 sterigmata; spores less than 9 microns long, ellipsoid, subcylindrical, suballantoid, or subglobose, uninucleate (except for S. binucleosporum)", (Hallenberg, Latin name underlined). "Even if the cultured SS-mycelia are of some other origin I am convinced that these specimens represent a distinct taxon. Among the hitherto known species in Sistotrema it seems to be rather isolated due to the binucleate spores, the very thin and firm fruitbody and the small basidia and spores", (Hallenberg, genus name underlined).
Microscopic: SPORES 3.3-3.8 x 1.5-1.8 microns, elliptic to subcylindric, smooth, thin-walled; BASIDIA 6-8-spored, 7-12 x 3-4 microns, urniform to ovate, with basal clamp connection; HYPHAE monomitic, with clamp connections, 1.5-3 microns wide, colorless, thin-walled; subhymenial hyphae "richly branched and densely united, short-celled, originating from more straight and sparsely branched, basal hyphae", (Hallenberg)