FAGACEAE. Nothofagus menziesii: Otago, Alton Valley, Tuatapere, 120 m, type collection, P.D.D. herbarium, No. 17418.

Hymenophore annual, membranous, adherent, effused forming irregular areas to 10 x 4 cm; hymenial surface cream, even, becoming deeply irregularly creviced; margin thinning out, white, fibrillose, adherent. Context white, to 250 µ thick, basal layer narrow, of intertwined hyphae, intermediate layer of erect hyphae embedding vesicles; generative hyphae 4-6 µdiameter, narrower in the subhymenium, walls 0.2 µ thick, naked, with clamp connections. Vesicles arising from context hyphae, subglobose or pyriform, 8-11 µ diameter, carried on stems to 30 µ long. Stephanocysts obovate or subglobose, 6-8 µ _{diameter, carried on short lateral branches of context hyphae, bearing on the distal hemispheres 5-8 flagella to 8 µ long, sometimes with ends inflated. Hymenial layer to 35 µ deep, a close palisade of basidia, paraphyses, and paraphysate hyphae. Basidia clavate, 28-40 x 7-8 µ, bearing 2-4 spores; sterigmata erect, slender, to 4 µ long. Paraphyses subclavate, 12-20 x 4-5 µ. Paraphysate hyphae scarcely projecting, scattered, capitate, with apices expanded to 8 µ. Spores obovate or elliptical, some flattened on one side, apiculate laterally or at bases, 8-9 x 5-6 µ, walls smooth, hyaline, 0.1 µ thick.}

TYPE LOCALITY: Tuatapere, Otago, New Zealand.
DISTRIBUTION: New Zealand.

HABITAT: Effused on decorticated decayed wood.

Hymenophorum membranaceum, adnatum, effusum; superficie cremes, aequa, deinde alte inaequaliter rimosa. Hyphae generatoriae fibulatae, 4-5 µ diam. Vesiculae subglobosae vel pyriformes, 8-11 µ. Stephanocystidia obovatae vel subglobosae, 6-8 µ, flagellis ad 8 µ longam. Basidia clavata, 28-40 x 7-8 µ, 2-4 sporis. Sporae obovatae vel ellipticae, 8-9 x 5-6 µ, parietibus levibus, hyalinis. On decayed wood of Nothofagus menziesii, Tuatapere, Otago, N.Z.

"Stephanocysts" are abundant, one-celled, stain deeply with aniline blue, and bear several long flagella upon the distal hemisphere of each. Capitate paraphysate hyphae are abundant in the hymenial layer and stain deeply with aniline blue.
Plants are resupinate and grow closely attached to the substratum, which supplies necessary support to the fructification. The hyphal system is monomitic, composed of generative hyphae alone, and there are no abhymenial hairs, or cortex, as in Stereum illudens.
The context is represented by a basal layer (fig. 2, a) of loosely arranged hyphae lying parallel with the substratum, and an intermediate layer (fig. 2, b) of mainly erect hyphae. Branches of hyphae arising from the basal layer penetrate the substratum, and lateral branches arise from erect hyphae of the intermediate layer to produce small vesicles, some of which bear flagella on the distal hemisphere.
The hymenial layer (fig. 2, c) is composed of a close palisade of basidia, paraphyses, and gloeocystidia. The last project slightly, and are slightly capitate. Basidia are subclavate and carry on slightly arcuate sterigmata four obovate or elliptical spores. Hyphae are naked and clamp connections are present at all septa.

Basal hyphae thin- to slightly thick-walled, 3-5(-6) µm wide, with rather small clamps. Echinocysts sessile or stalked, hyaline, globose to ellipsoid or ovoid, 6-11 X 6-8 µm, strongly cyanophilous, with a basal clamp, apically with 4-8 slender, tortuous "flagella" up to 8 µm long. Cystidia hyaline, thin-walled, clavate to generally cylindrical and constricted below the apex, thus becoming capitate, 28-40 X 5-6.5 µm. apex up to 8 µm wide, constriction 2.4-4 µm wide. Basidia clavate to typically urniform, 30-50 X 7-9(-10) µm, with four sterigmata. Spores hyaline, thin-walled, ellipsoid to subcylindrical, (7-)8-10(-10.5) X (4-)4.5-5(-6) X (4.5-)5-6(-6.5) µm, smooth, not amyloid.

The species is very close to Hyphoderma comptum (H. S. Jacks.) Jülich, which has similar, but significantly smaller structures. Stephanocysts, echinocysts, and small vesicles are considered to be homologous; they are all strongly cyanophilous, have a basal clamp directly under the swelling, and are found in the subiculum only. Moreover, in H. flagellatum both vesicles with flagella (echinocysts) and similar vesicles without flagella are present. Species with these structures generally also have cystidia with a constriction directly below the apex; they are considered to be closely related. To this group belong: H. comptum, H. echinocystis J. Erikss. & Strid, H. flagellatum and H. praetermissum (P. Karst.) J. Erikss. & Strid.