Cunningham (1965: 130) placed the name in synonomy under Tyromyces chioneus (Fr.) P. Karst. However, it is obvious from Cunningham's description that his concept of T. chioneus is different from the Friesian concept. Cunningham described spores as 2.5-3.5 x 0.5 µm which agree with our measurements from the type of 2.8-3.3 x 0.4-0.5 µm. This is much smaller than in Fries' species, 3.5-4.5 x 1.5-2 µm (Ryvarden, 1978). Furthermore, the Friesian species is never resupinate.
Cunningham (1947, 1965) described the hyphal system of C. coprosmae as dimitic, but careful examination of the thick-walled 'binding' hyphae shows the occasional clamp. The hyphal system is monomitic with walls of generative hyphae varying from thin to irregularly thickened, to very thick or even solid.
Ceriporiopsis Dom. includes species with resupinate, light-coloured fruit-bodies with a monomitic hyphal system and clamps at the septa. No prominent sterile hymenial organs, such as cystidia, are known in the genus, and all species cause a white rot. These characters are found in C. coprosmae and we include it in Ceriporiopsis as defined in Gilbertson & Ryvarden (1986). Niemela (1985) has separated species like Polyporus pannocinctus Rom. and Poria subvermispora Pilat in the genus Gelatoporia Niem. because in both these species gelatinized hyphal layers are present in the fruit-body. Such structures or zones are not present in C. coprosmae.
Cunningham (1965: 131) stated that his Tyromyces chioneus was described by Overholts (1953) as Polyporus semipileatus Peck. This is a misunderstanding. P. semipileatus is a synonym of P. niveus Jungh. and is currently either placed in Incrustoporia Dom. or Skeletocutis Pouz. because of the characteristically encrusted hyphae, especially in the dissepiments. Furthermore, the species is dimitic or semi-trimitic with some branched solid hyphae which have sometimes been described as binding hyphae. Encrusted hyphae of the kind found in Incrustoporia are absent in C. coprosmae.

Holotype: PDD 5252 - New Zealand, Westland, Lake Mapourika, Nov. 1946, J.M. Dingley, on Coprosma sp.