Type: Lignicolous Fungi; Description: Basidiomata perennial, solitary, hard, leathery or woody, attached by a broad lateral base. Pilei applanate or ungulate, 30–200 mm wide, 10–100 mm thick. Pileus surface tomentose, becoming glabrous, strongly concentrically sulcate, often banded in different shades of brown or grey, becoming deep brown to umber with age. Pore surface slightly convex, with a narrow sterile border 2–3 mm wide, white, pores in many strata, small, 6–7 per mm. Context cream, often zoned, up to 15 mm thick; in cross-section, a thin orange line is visible immediately beneath the pileus surface. Hyphal system dimitic. Basidiospores elliptic-oblong, 4–6 × 2–3 μm, smooth, hyaline.

Distribution: Northland, Auckland, Coromandel, Waikato, Bay of Plenty, Taranaki, Taupo, Wanganui, Wellington, Gisborne, Hawkes Bay, Wairarapa, Nelson, Buller, Westland, Fiordland, Marlborough, Mid Canterbury, Otago Lakes, Dunedin, Southland, Stewart Island.; 1st Record: Colenso (1887: as Fomes (Laevi) hemitephrus).

Significance: Causes a white heart rot with orange zone lines. It is one of the commonest perennial bracket fungi in indigenous forests.; Host(s): Agathis australis, Beilschmiedia tarairi, B. tawa, Dacrydium cupressinum, Knightia excelsa, Nothofagus fusca, N. menziesii, N. solandri var. solandri, N. solandri var. cliffortioides, N. truncata, Pseudopanax arboreus, Weinmannia racemosa.

CULTURE STUDIED: NEW ZEALAND, Westland, Westland National Park, Lake Matheson, M. Rajchenberg 10085, 7.V.89 (BAFC/cc 495; basidiome at BAFC).

MACROSCOPIC CHARACTERS (Fig. 1): Growth rapid, dishes covered in 3 weeks. Growing margin regular, felty-farinose. Mat first woolly with denser radial stripes near the inoculum. At week 6, mat white, tightly felty to plaster-like at the margin, with or without sunken areas. In the centre becoming loose felty to woolly. Around the inoculum it is tightly felty. Pale yellow areas are present in the subfelty and/or felty areas. Mat growing on the glass and then presenting orange-yellow tints. Reverse bleaching. Odour acidic or none.
OXIDASE REACTIONS: tannic acid: ++++, trace gallic acid: ++++, 0 mm tyrosinase: -, 12 mm
MICROSCOPIC CHARACTERS (Fig. 2): Marginal hyphae regularly clamped, 3-4(-5) µm diam., thin-walled and sparsely branched. Woolly, felty, and plaster-like areas with many aerial fibre hyphae, 1-1.5(-2.0) µm diam., branched, with hyaline, slightly thickened walls. Pale yellow subfelty areas with submerged mycelium differentiated into cuticular cells that form pseudoparenchymatous areas, with cell walls thickened up to 1-3.5 µm.
SEXUALITY: Seemingly tetrapolar. Ten single monospore cultures were distributed as: A₁B₁:1,2,3,4,6,8; A₂B2: 9, 10; A_XB_X: 5, 7
NUCLEAR BEHAVIOUR: Normal.
CODE: 2.3c.8.10.32.36.37.40.43.54.60.61

REMARKS: Fomes hemitephrus is one of the most common polypores in New Zealand and Australia, and it damages several tree species. Nevertheless, no detailed study of its cultural features has been reported. Refshauge & Proctor (1935) only gave general features. Stalpers' (1978) report of this species in culture does not support the fact that the species causes a white rot in wood and was perhaps based on an old culture or a different taxon. Good basidiome descriptions may be found in Cunningham (1965) and Teixeira (1962).
Fomes hemitephrus has been included or accepted in Fomitopsis Karst. (Cunningham 1948; Ryvarden 1977), Heterobasidion Bref. (Cunningham 1965), and Trametes Fr. (Corner 1989). Teixeira (1962) supports the disposition of this species in Fomes (Fr.) Fr., a disposition with which I concur because of the following characteristics: perennial fruit body, trimitic hyphal system, smooth, hyaline, cylindric spores, pileus covered with a hard smooth crust, production of a white rot, tetrapolar sexuality, production of cuticular cells in culture, and normal nuclear behaviour.
Fomitopsis includes brown wood-rotting species with bipolar sexuality, and most of the species produce generative hyphae with irregularly thickened walls in culture (Carranza-Morse & Gilbertson 1989); hence, the species does not belong in Fomitopsis, as suggested by Hood (1992). Although currently known in New Zealand as Heterobasidion hemitephrus (Berk.) G.H. Cunn. due to Cunningham (1965), Fomes hemitephrus cannot be included in Heterobasidion Bref. Heterobasidion is restricted to fomitoid species with a dimitic hyphal system of simple-septate generative hyphae and skeletal hyphae, and with asperulate spores. Ryvarden (1977) stated that Cunningham's concept of Heterobasidion was too broad. Some support that Heterobasidion is related to the Bondarzewiaceae (Stalpers 1980; Gluchoff-Fiasson et al. 1983). The inclusion of F. hemitephrus in Trametes by Corner (1989) is also not accepted here. It is beyond the limits of that genus (Ryvarden 1991) which includes annual species, lacking a crust on the pileus.
Fomes hemitephrus differs from the type species of the genus, F. fomentarius (L.:Fr.) Kickx., in its creamy to light chestnut colouration of the context and dissepiments, and the lack of sclerids in the context (Gilbertson & Ryvarden 1986). Nevertheless, it shares all other morphological features. I note also that it develops cuticular cells in culture as does F. fomentarius. This character is rarely seen in cultures of trametoid and fomitoid species (Nobles 1965; Stalpers 1978).