Under (1) N. fusca. Nelson: L. Daniels track, 14.V.1969, R. F. R. McN. (holotype, pdd 30660); Karamea, Umere, 4.L1970, R. F. R. McN. (2) N. menziesii. Nelson: L. Daniels track, 14.V.1969, (2 coils) 15.V.1969, 16.V.1969, R. F. R. McN.; Karamea, Umere, 29.xii.l969, R. F. R. McN. (3) N. menziesii N. fusca, Nelson: Manila, 27.iii.l970, R. F. R. McN. (4) N. truncata. Nelson, Karamea, Granite Creek, 12.V.1971, R. F. R. McN. (2 coils): Taffytown, IO.v-1971, R, F. R. McN.; Karamea, Umere, 611971, IO.V.1971, 14.V.1971, R. F. R. McN.

pileus: 4.5-7 cm diam., convex when young, centrally depressed at maturity, slightly viscid under wet conditions, otherwise dry, finely subpruinose under lens, velar remnants absent, dark magenta to greyish magenta, or greyish purple, frequently with yellow, greenish yellow, dull olive green, or dark reddish brown areas; margins entire, thick, non-pectinate. Cuticle composed of erect, thin-walled, smooth, septate, hair-like hyphae to 100 µm long, 2.5-4.5 µm diam., without staining contents in KOH, terminal cells unspecialised, tapering apically, originating from inflated, short-celled hyphae arising from a layer of sphaerocysts, becoming disorganised with age; pilocystidia absent: lamellae: adnate, moderately crowded, thin, simple or forked near stipe, to 12 mm deep, creamy yellow to pallid yellow, not discoloured at maturity but edges typically tinted with colours of stipe, lamellulae rare or absent. stipe: 2.5-5 cm long, ± equal or slightly expanded basally, 1-2.3 cm diam., dry, solid, finely furfuraceous under lens, pallid greyish magenta or pallid greyish purple, often with rose tints, flesh often showing through; flesh white, unchanging on exposure to air. Cuticle composed of interwoven, repent, thin-walled, septate hyphae 2.5-5 µm diam., terminal cells projecting and aggregated into clumps, caulocystidia absent. spores: spore print not obtained; spores broadly elliptical to ovate, obliquely apiculate, apiculus to 1.5-(2) µm long. 8.5-10.5 X 7.5-9.5 ornamentation of amyloid or partially inamyloid truncated spines to l- (1.5) µm high, in small confluent groups, joined basally by fine amyloid ridges and forming an incomplete reticulum, or occasionally isolated; plage weakly amyloid, inconspicuous. hymenium: basidia hyaline, clavate, 42-53 X 10-12 µm, 4-spored, sterigmata to 7 µm long; pleurocystidia scattered, numerous, fusiform or sub-clavate, hyaline, thick-walled, walls to 6 µm thick at mid point, thinner at base and apex, contents refractive in KOH, projecting to 25 µm beyond basidia, apices acuminate, strangulate, or mucronate, occasionally capitulate, 60-110 X 9-13 µm, cheilocystidia numerous, filamentous, septate, simple or occasionally sparingly branched apically, to 5 µm diam. hymenophoral trama: heteromerous, intermixed. context of pileus: creamy yellow to pallid yellow, unchanging; structure heteromerous, clamp connections absent. taste: lamellae slowly acrid, context mild. chemical characters: formalin on context—n.r.; phenol on context— slowly slate grey with purplish or vinaceous tints; FeSO4 on context— rapidly salmon pink; guaiacol on stipe base—n.r.; KOH on pileus— magenta colour disappears leaving area orange-red; on context—n.r.; NH4OH on pileus—green; on context—n.r.

Solitary or gregarious under Nothofagus.

Pileus centraliter depressus, 4.5-7 cm diam., fusco-magenteus ad griseo. purpureum, subtiliter pruinosus; veli vestigia deficiunt; margines integri, crassi, nor pectinati. Lamellae adnatae ad 12 mm altae, cremeo-flavae; lamellulae rarae. Stipes 2.5-5 cm longus, plus minusve aequalis, 1-2.3 cm diam., solidus, siccus. subroseo-ruber. Sporae late ellipticae 8.5-10.5 X 7.5-9.5 µm, amyloides dense ornatae.

The species is characterised by the creamy yellow lamellae, typically with purplish tinted edges, thin-walled pleurocystidia, thin-walled filamentous cheilocystidia, and the slowly acrid taste of the lamellae. The combination of colour reactions to phenol, KOH, and NH4OH is also characteristic. Russula tawai belongs in section Rigidae and is possibly best assigned to subsection Amoeninae (Singer 1962).

holotype, pdd 30660