Hymenophore annual, membranous, adnate, effused forming irregular areas to 7 x 4 cm; surface white or ivory white, even, not creviced; margin thinning out, arachnoid, white, adnate. Context white, 60-100 µ thick, basal layer scanty, of parallel hyphae; intermediate layer of loosely arranged ascending hyphae branched at a wide angle, corymbose in the subhymenium; generative hyphae 3-4 µ diameter, walls 0.25 µ thick, hyaline, naked, branched, septate, with conspicuous clamp connexions. Hymenial layer to 25 µ deep, a scanty and irregular palisade of basidia, paraphyses and cystidia. Basidia subclavate, 16-20 x 4-5 µ, 4-spored; sterigmata slender, arcuate, 6-8 µ long. Paraphyses scanty, subclavate, or cylindrical, shorter than the basidia. Cystidia arising from hyphae of the intermediate and basal layers, projecting to 60 µ, aculeate with long-acuminate apices, 64-105 x 5-7 µ, coated save at apices with scanty flattened crystals, walls hyaline, 0.5-1 µ thick, thinning towards apices. Spores elliptical when flattened on one side, or suballantoid, 7-9 x 4-5 µ, walls smooth, hyaline, 0.1 µ thick.

DISTRIBUTION. New Zealand.

HABITAT. Effused on dead leaf midribs.

Hymenophorum annuum, membranaceum, adnatum, effusum; superficie alba, aequa, non rimosa. Hyphae contextus fibulatae, 3-4 µ diam., nudae. Basidia subclavata, 16-20 x 4-5 µ, 4 sporis. Cystidia aculeata, eminentia, 64-105 x 5-7 µ, crystallis sparsis verrucosis tecta. Sporae elliptical vel suballantoides, 7-9 x 4-5 µ, laeves, hyalinae.

P. sororia and P. longispora show a close resemblance in structure of the context and especially the form of the cystidia. The latter are aculeate, taper from base to apex, project for about half their length, are relatively thin-walled, and bear small tuberculate scattered crystals often arranged like plates or scales. P. sororia is separated by its differently shaped shorter spores, and more delicate cystidia being, as its name implies, a little sister of the more robust P. longispora.

Rhopalostylis sapida (Sol.) Wendl. & Drude. Auckland: Cascades, Waitakeres, 900ft, April, 1954, S.D. Baker, type collection, P.D.D.herbarium, No. 13816.

PALMAE. Rhopalostylis sapida: Auckland, Cascades, Waitakere Ranges, 300 m, type collection, P.D.D. herbarium, No. 13816.

Hymenophore annual, membranous, adherent, effused forming irregular areas to 7 x 4 cm; hymenial surface white or ivory, not creviced, even; margin thinning out, arachnoid, white, adherent. Context white, 60-100 µ thick, basal layer scanty, of parallel hyphae, intermediate layer of loosely arranged ascending hyphae branched at a wide angle, corymbose in the subgymenium, generative hyphae 3-4 µ diameter, walls 0.2 µ thick, hyaline, naked, with clamp connections. Metuloids arising from hyphae of the intermediate and basal layers, projecting to 60 µ, aculeate with longacuminate apices, 64-105 x 5-7 µ, encrusted save at apices with scanty flattened crystals, walls becoming thinner towards apices. Hymenial layer to 25 µ deep, a scanty and irregular palisade of basidia, paraphyses, and metuloids. Basidia subclavate, 16-20 x 4-5 µ, bearing 4 spores; sterigmata slender, arcuate, 6-8 µ long. Paraphyses scanty, subclavate or cylindrical, 8-14 x 3-4 µ. Spores elliptical or suballantoid, 7-9 x 4-5 µ, walls smooth, hyaline, 0.1 µ thick.

TYPE LOCALITY: Waitakere Ranges, Auckland, New Zealand.
DISTRIBUTION: New Zealand.

HABITAT: Effused on dead leaf midribs.

P. nikau and P. longispora show a close resemblance in structure of the context and especially in shape of metuloids. The latter are aculeate, taper from bases to apices, project for about half their length, are relatively thin-walled, and bear small tuberculate, scattered crystals often resembling plates or scales. P. nikau is separated by its spores of different shape and size, and more delicate metuloids. In a former paper it was described under the name of P. sororia; as this is occupied (Bourdot & Galzin, 1912, p. 386) the species has been renamed after the Maori name of the host.

Basidiome effused, thin-arachnoid, white. Basal hyphae hyaline, thin-walled, 2-3 µm wide, with clamps. Cystidia thin-walled, acuminate, up to 110 µm long, apically 2 µm wide, basally up to 7.5 µm wide, covered with plate-like crystals. Basidia thin-walled, in dense clusters. Spores hyaline, thin-walled, smooth, ellipsoid to allantoid, 7-9 x 3.2-4.2 x 3.8-5 µm, not amyloid.

The species belongs to Subulicystidium Parm. The nature of the cystidia is similar to that of S. longisporum (Pat.) Parm. as described by Jülich (1975).

Holotype: on Rhopalostylis sapida Wendl. & Drude, New Zealand, Auckland, Waitakere Ranges, Cascades, coll. S.D. Baker, Apr. 1954 (PDD 13816).