Cunningham described this species in Irpex Fr. mainly because the pore mouths in mature specimens are partly split. However, this macroscopic feature is now considered to be of minor importance in delimiting genera. Many genera, such as Antrodia P. Karst., Trametes Fr., and Spongipellis Pat., include some species with a regular pore surface and others with a more or less dentate one. Irpex is typified by I. lacteus Fr. (see Maas Geesteranus, 1974), a distinctly hydnoid species with a dimitic hyphal system. The generative hyphae are simple septate and the cystidia develop from protruding skeletal hyphae which are encrusted over a considerable length. The cystidia in O. spiculifer are typically ventricose and apically encrusted, although some hyphae in the dissepiments are encrusted over longer segments. The cystidia and monomitic hyphal system of O. spiculifer indicate that it does not belong in Irpex.
Oxyporus Donk is characterised by a monomitic hyphal system with simple septate generative hyphae and mostly apically encrusted cystidia. O. pellicula (Jungh.) Ryv. from tropical Africa and Asia is similar in many respects to O. spiculifer, with a dentate, lacerate pore surface, but its spores are larger and more broadly ellipsoid. Spores of O. spiculifer measure 5-6.5 x 2.5-3 µm, larger than the dimensions given by Cunningham (1965) of 4-5 x 1.5-2 µm. From herbarium material, the type of rot appears to be white.

Holotype: PDD 19144 - New Zealand, Buller, vic. Reefton, Staircase Creek, 29 Nov. 1952, S.D. Baker, on Nothofagus fusca (Hook. f.) Oerst.

FAGACEAE. Nothofagus fusca: Nelson, Staircase Creek, Reefton, 700 m, type collection, P.D.D. herbarium, No. 19144. PROTEACEAE. Knightia excelsa: Auckland, Waikaretu, 130 m.

Hymenophore annual, coriaceous, almost resupinate, forming. irregular adherent areas to 10 x 5 cm, to 3.5 mm thick. Pilei represented by upturned margins or irregular ridges in the hymenial layer, to 3 mm radius, surface even, clay colour; margin thinning out, cream or clay colour, with a pallid sterile border to 5 mm wide; hymenial surface cream or tan, irregular, not creviced. Pores 1-2 per mm, to 3 mm deep, dissepiments soon torn into tapering spines with acuminate finely velutinate apices, sometimes collapsing so that pores are 1-3 mm across. Context to 0.25 mm deep, cream in section, of densely intertwined hyphae almost sclerotioid next the substratum; generative hyphae 3-6 µm diameter, walls 0.2 µm thick, branched, septate, without clamp connections. Metuloids present in the hymemal layer and dissepiments; in the hymenial layer fusiform, or ventricose, with long acuminate apices, projecting to 20 µm, and forming a dense palisade of 2-3 irregular rows in the subhymenium of mature dissepiments, 16-30 x 4-6 µm, walls hyaline, thin, crystal encrusted; in dissepiments cylindrical, to 6 µm diameter, upwards of 100 µm in length, walls crystal encrusted. Hymenial layer to 25 µm deep, a dense palisade of basidia, paraphyses, and cystidia. Basidia subclavate, 12-20 x 3.5-4.5 µm, bearing 2-4 spores; sterigmata erect, to 4 µm long. Paraphyses subclavate, 8-14 x 3-3.5 µm. Spores obovate or suballantoid, apiculate, 4-5 x 1.5-2 µm, walls smooth, hyaline, 0.1 µm thick.

New Zealand.

Bark and decorticated wood of fallen branches and trunks.

Hymenophorum annuum, coriaceum, paene resupinatum, 10 x 5 cm, ad 3.5 mm crassum. Pilei marginum reversorum, 3 mm radii, superficie aequali, alutacea. Hymenii superficies inaequalis, non rimosa. Pori 1-2 per mm, ad 3 mm alti, dissepimentis in spinis apiculatis corruentibus. Contextus ad 0.25 mm altus, hypharum solide intertextarum. Hyphae generatoriae 3-6 µm diam., parietibus 0.2 µm crassis, ramosae, septatae, enodulosae. Metuloides adest; in hymenio ad 20 µm, eminentes, in dissepimentis ad 100 µm , longi. Basidia subclavata, 12-20 x 3.5-4.5 µm, 2-4 sporas in sterigmatis ad 4 µm longis gerentia. Sporae obovatae vel suballantoides, apiculatae, 4-5 x 1.5-2 µm, laeves, hyalinae. On dead bark of Nothofagus fusca, Reefton, Nelson, N.Z.

Specific features are the almost resupinate fructifications, metuloids of two types, monomitic hyphal system without clamp connections on generative hyphae, and small suballantoid spores. Pilei are represented by narrow upturned margins, or by occasional reflexed portions of the hymenial layer (in plants growing vertically) and are smooth and clay coloured on the surface. Metuloids of the hymenial layer are ventricose or fusiform with long acuminate apices, and thin walled but crystal encrusted. Near the apices of pores or spines they occur in a single layer, but in older tissues they are arranged in two or three irregular rows forming a dense palisade beneath the subhymenium, embedded in mucilage granules; some are partly coloured. Metuloids of the dissepiments are cylindrical, with densely crystal encrusted walls, and may exceed 100 µm in length. Generative hyphae are thin-walled, freely septate, scantily branched, without clamp connections and densely compacted into an almost sclerotioid layer above the substratum.