Junghuhnia rhinocephalus, a rather widespread species in Australia and New Zealand, is somewhat deviating in the genus Junghuhnia Corda since vegetative hyphae are light brown and the context is ochraceous to dark cinnamon. Most other species in the genus have hyaline hyphae and a white, ochraceous to yellowish context, although the context of J. collabens (Fr.) Ryv. is cocoa-brown. This variation in context and hyphal colour is accepted within the genus.
Cunningham (1965) described both Trichaptum rhinocephalum and Trametes tawa and considered them to be distinct species. He examined only the type collection of J. rhinocephalus, from Kew, and four small fragments apparently from this collection were retained (PDD 28062). Examination of these fragments reveals a mixed collection. Three fragments, which are sterile, correspond to J. rhinocephalus, while a fourth is of a different polypore species with a white context, hyaline hyphae, simple septate generative hyphae and subglobose spores, 5-5.5 x 4.5-5.5 µm. These characters appear in Cunningham's description of Trichaptum rhinocephalum, indicating that he mistakenly based at least part of his description on the discordant element. J. rhinocephalus should have been described with a brown context, light brown vegetative hyphae, clamped generative hyphae, and ellipsoid spores measuring 3.5-4 x 2-2.5 µm.
A more accurate description of J. rhinocephalus was given by Cunningham (1965) for Metuloidea tawa, which he designated the type species of Metuloidea G.H. Cunn. This genus, mainly characterised by brown vegetative hyphae and encrusted cystidia, becomes a synonym of Junghuhnia.