This species is closely related to Cylindrobasidium albulum (G.F.Atk. & Burt) J. Erikss. & Hjortstam and C. torrendii (Bres.) Hjortstam, preferably by its morphology of spores and cystidia. The former are typically pip-shaped and often in pairs or 3-4. C. coprosmae seems to be rather well separated from both, above all by a very dense hyphal texture and basidial layer. There is a good original description and Cunningham also pointed out the similarity with Corticium evolvens Fr.:Fr. [=Cylindrobasidium evolvens (Fr.:Fr.) Jülich]. It should be noted that Stalpers (1985) transferred C. coprosmae to Chondrostereum Pouzar. The latter is a pileate (or sometimes resupinate) genus with differently shaped spores and is reminiscent of Phlebia Fr. (see Eriksson and Ryvarden 1973). Chamuris (1988) did not accept C. coprosmae in Chondrostereum.

Isotype: New Zealand, Auckland, 1946, J. M. Dingley, PDD 4528 (K).

The species is similar to Mycoacia fuscoatra (Fr.:Fr.) Donk, but differs by columns of crystals in the middle part of the aculei and by ellipsoid spores.

The spores are similar to those of Mycoacia uda (Fr.) Donk, but otherwise well distinguished by larger cystidia.

Corticium umbonatum is a typical species of Xerrasma by its lateral basidia and rugose spores and is known from different kinds of bamboo; Arundinaria, Pseudosasa and once on Ripogonum (Liliaceae). Cunninghammyces Stalpers is considered as a synonym of Xerrasma Donk.