ADDITIONAL SPECIMEN EXAMINED: Three King Islands: Great King I., on Kunzea ericoides, P. Brook, Dec 1955, PDD 17483.

Basidiocarps annual, resupinate, adnate, comprising small (to 0.5 cm diam.) cushion-shaped basidiocarps which may coalesce, then up to 5.5 x 2 cm, up to 2 mm thick; margin varying from negligible to a slightly raised band to 2 mm across; pores cream to fawn (73.p.OY) or yellow-brown (71.m.OY - 76.1.y Br), angular, 1-2 per mm, dissepiments thick, tubes broad, to 1 mm deep; context to 0.5 mm thick, cream to pale yellow-brown. Hyphal system dimitic; generative hyphae hyaline, thin-walled, clamped, relatively sparse, 1.7-3.5 µm diam.; arboriform binding hyphae dominant, hyaline, thick-walled (wall to 1.5 µm) to almost solid, IKI-, branched, sometimes dichotomously towards ends, 2.5-5(-7) µm diam.; hyphal system similar in trama and context; crystals amongst hyphae towards hymenium. Cystidia not seen. Cystidioles occasional amongst basidia, cylindrical, with papillate apex 26-35 x 6.5-10 µm. Basidia clavate, mostly with long tapering base, clamped at base, 4-sterigmate 30-53 x 5.5-13 µm. Basidiospores broadly cylindrical, straight or mostly weakly curved (sausage-shaped), with distinct apiculus, hyaline, thin-walled, IKI-, 0(-4)-septate, 0-septate 12.5-21.5(-23.5) x 5.5-7(-9) µm, 1-4-septate 15.5-21.5 x 6.5-8 µm. Causing a white wood rot.

Northern New Zealand, know from Auckland and Three Kings Islands.

SUBSTRATA: Known from dead wood of ?Knighia excelsa and Kunzea ericoides.

Basidiocarpi annui, resupinati, pulviniformes, pusilli (usque 0.5 cm diametro), quum coalescentes usque 5.5 x 2 cm; pori cremei vel hinnulei vel ochracei, 1-2 per mm; tubi usque 1 mm profunditate; contextus usque 0.5 mm crassus, cremeus vel pallide ochraceus. Systema hyphale dimiticum; hyphae genitales tenuitunicatae, fibulatae, 1.7-3.5 µm diametro; hyphae ligantes arboriformes, hyalinae, crassitunicatae (tunica usque 1.5 µm) vel subsolidae, IKI -, 2.5-5(-7) µm diametro. Cystidiola aliquando visa, cylindrica, apice papillata, 26-35 x 6.5-10 µm. Basidia clavata, basi longe decrescentia, basi fibullata, 4-sterigmatophora, 30-53 x 5.5-13 µm. Basidiosporae late cylindraceae, rectae vel leniter curvatae, hyalinae, tenuitunicatae, IKI-, 0(-4)-septatae, 0-septatae 12.5-21.5(-23.5) x 5.5-7(-9) µm, 1-4-septatae 15.5-21.5 x 6.5-8 µm. Cariem albam efficiens.

ETYMOLOGY: newhookii, named after the collector of the holotype collection, the late Professor Frank J. Newhook, professor emeritus of plant pathology at University of Auckland, and one of New Zealand's foremost plant pathologists.
NOTES: D. newhookii is distinguished from other species in the genus by the large size of the basidiospores, and the development of septa in a minority of basidiospores. Of 100 spores examined from within tubes of the holotype, seven were 1-septate and one was 3-septate. Septate spores were not significantly larger than nonseptate spores. The holotype specimen appears to have been overmature when collected as indicated by the degenerated hymenium and contaminant hyphomycete fungi. Septate spores were not seen in PDD 17483.
Both collections were identified by G. Cunningham as Poria leucoplaca (Berk.) Cooke (=Dichomitus leucoplacus (Berk.) Ryvarden), a species with smaller pores ((3-)4-5 per mm) and spores (10-14 x 4-5.5 µm) (Masuka & Ryvarden 1999) than D. newhookii. D. campestris (Que1.) Doman. & Orlicz has large pores (1-2(-3) per mm) and spores almost as large (13-19 x 4-6.5 µm) (Gilbertson & Ryvarden 1986; Ryvarden & Gilbertson 1993), but has larger and much thicker (-15 mm) basidiocarps and a blackened margin. A Ugandan specimen (TRTC 66843) reported by Ryvarden & Johansen (1980) as Dichomitus sp. appears to have similar small fruitbodies with large (1-2 per mm) pores but dissepiments are described as thin-walled and spores are smaller, 15-17 x 5-6.5 µm. Septation of spores was not reported for these other species.
The only other polypore species known to have septate spores is Polyporus septosporus P.K.Buchanan & Ryvarden (Buchanan & Ryvarden 1998). Septation appears to be related to spore maturity, with some septate spores of D. newhookii in the early stages of germination and those of P. septosporus being most common amongst released spores examined from the pileus surface. The close relationship between the genera Dichomitus and Polyporus is well documented (e.g., Masuka & Ryvarden 1999).
In macroscopic appearance of pores, basidiocarp form, and colour, D. newhookii strongly resembles the New Zealand species Perenniporia podocarpi P.K.Buchanan & Hood, but the latter species has distinctly thick-walled spores and both spores and vegetative hyphae are dextrinoid (Buchanan & Hood 1992).

HOLOTYPUS: New Zealand, Auckland, Little Barrier I., Awaroa Stream, on ?Knightia excelsa, F. J Newhook, 10 Jun 1956 (PDD 17301).