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.

Beilschmiedia tarairi (A.Cunn.) Benth. & Hook.f. Auckland. Near Alfriston, Sept. 1941, Joan Dingley. Beilschmiedia tawa (A.Cunn.) Hook.f. & Benth. Auckland. Waitomo, 400 feet, Aug. 1946, G.H.C.; Little Barrier Island, Nov. 1947, Joan Dingley. Coprosma sp. Auckland. Whakarewarewa, May, 1947, G.B.Rawlings. Dysoxylum spectabile (Forst.f.) Hook.f. Auckland. Te Moehau: Coromandel, 600 feet, Jan. 1941, Joan Dingley. Nothofagus cliffortioides (Hook.f.) Oerst. Wellington. Butterfly Reserve, May 1946, G.B.Rawlings. Pittosporum sp. Southland. Woodlaw State Forest, Nov. 1946, G.B.Rawlings, type collection.

Hymenophore annual, dimidiate, often imbricate, coriaceous. Pileus conchate, or applanate, often effused-reflexed, or as frequently attached by a narrow base, when gibbous, 1-3 cm. x 1-2 cm. x 1-3 mm.; sometimes resupinate when to 11 cm. x 2 cm.; surface at first cream, zoned and almost smooth, soon becoming bay-brown, sometimes reddish-brown, azonate, coarsely strigose, hairs often adpressed and somewhat radiately arranged, somewhat scrupose at the base, cuticle absent; margin bluntly rounded, even, concolorous; hymenial surface ochraceous, bay-brown, ferruginous, or chestnut-brown, even, sterile border lighter in colour, l-2 mm. wide, finely velutinate, dissepiments not toothed. Context 0.5-1 cm. thick, bay-brown or chestnut-brown, vaguely zoned; skeletal hyphae 5-6 µ thick, lumen 1-2 µ, sparsely or not branched, aseptate, tinted yellow or chestnut-brown; binding hyphae 3.5-4 µ thick, lumen 1 µ, branched, aseptate, tinted yellow; generative hyphae 2-3 µ thick, delicate walled, septate, branched, hyaline. Pores angular or round, ferruginous in section, 100-150 µ diameter, or 5-6 per mm., sometimes to 2 mm. long; dissepiments 50-100 µ thick, equal, apex finely velutinate. Cystidia tinted yellow, to 140 µ long, 6-10 µ diameter, wall 2 µ, sparse, encrusted save at apices. Basidia clavate, 10-14 x 4-5 µ. Spores elliptical, a few slightly allantoid, 2.5-3.5 x 1.5-2 µ, smooth, hyaline.

DISTRIBUTION: New Zealand.

HABITAT: Growing usually imbricate, sometimes resupinate, upon bark of dead upright branches, associated with a white rot.

Hymenophorium annum, dimidiatum, saepe imbricatum, coriaceum. Pilei conchati vel applanati, saepe effuso-reflexi, vel saepe si quibbosus basi angustato fixi, 1-3 cm. x 1-2 cm. x 1-3 mm., interdum resupinati si ad 11 cm. x 2 cm.; superficies primo cremea, zonata fere zaevigataque, mox badia interdum testacea, azonata, crasse strigosa, pilis saepe appressis aliquantum radiatim dispositis, basi aliquantum scruposis, cuticula absens; margo obtuse rotundatus, aequus, concolorus; superficies hymenialis ochraceus, badius, ferrugineus, vel castaneus, aequus, margo sterilis pallidior, 1-2 mm. latus, subtiliter velutinatus, dissepimentis haud dentatis. Contextus 0.5-1 cm. crassus, badius vel castaneus, ambigae zonatus; hyphae skeletales 5-6 µ crassae, lumen 1-2 µ, sparse vel vix brachiatum, aseptatum, flavo-tinctum vel castaneum, hyphae genitales 2-3 µ crassae, muris teneribus, septatae brachiatae, hyalinae. Pori angulati vel rotundati, sectione ferruginei, 100-150 µ diam. vel 5-6 per mm., interdum ad 2 mm. longi, dissepimenta 50-100 µ crassa, aequa, apicibus tenuiter velutinata. Cystidia flavo-tincta ad 140 µ longa, 6-10 µ diam., muris 2 µ crassis, sparsa, encrustata apicibus exceptis. Basidia clavata 10-14 x 4-5 µ. Sporae ellipticae, paucae aliquantulum allantoideae, 2.5-3.5 x 1.5-2 µ, laevigatae, hyalinae.

Fresh plants possess a pleasant odour resembling face powder. An unusual feature is the presence of large hyaline or tinted cystidia. They resemble those of Poria eupora, attain a length of 140 µ, diameter of 10 µ and, save at the apex, are encrusted with crystals. It is probable that records of the presence in New Zealand of Polyporus pargamenus Fr. and P. pinsitus Fr. (Colenso 1886, p. 303; 1895, p. 614) were based on this species. Both differ, however, in configuration of the hymenium, spores, and different cystidia.

Pittosporum sp. Southland. Woodlaw State Forest, Nov. 1946, G.B.Rawlings, type collection.