New Zealand: North Is.: Northland: Tangihua Forest, Rope Walk near Lodge, P.R. Johnston & B.P. Segedin, 20 May 1992, PDD 60267.

Basidiome very small (1-6 mm diam.), dorsally attached to host moss plant or to rhizomorphs, pendent, attached by a short pseudostipe, usually more or less centrally; young specimens resembling a minute tobacco pipe. Pileus narrowly to broadly parabolic, becoming convex, pure white, dry, floccose to villose near the pseudostipe, grooved following the outline of the lamellae, margin strongly inrolled when young, becoming almost straight at maturity and sometimes slightly undulating. Hymenophore white to pale salmon pink when dry, smooth in very small basidiomes, but more usually lamellate, lamellae fold-like, thick, shallow, becoming more distant in dried material, 3-4 principal veins meeting at a central to sub-central point, forking or anastomosing with 1-2 series of lamellae. Taste and odour not noticeable. Spore print not known. Spores 5-6.6 x 4.5-5.5 (5.2 x 4.8) µm, Q = 1.09, spherical to subspherical with a conspicuous apiculus often with a noticeable scar, hyaline, inamyloid, not dextrinoid, acyanophilic, very thinwalled. Basidia 20-23 x 6-8 µm, 4-spored, with relatively long sterigmata (-6 µm), which are so well separated on the rather broad basidia that the basidia may very often appear 2-spored. Cheilocystidia and pleurocystidia absent. Trama subparallel to somewhat interwoven, hyphae 3-8 µm diam., many inflated. Subhymenium also of loosely packed, inflated cells equal to or greater in diameter than those of the trama. Context of interwoven, narrow (5 µm diam.) to inflated (-11 µm diam.) hyphae, those near the surface repent and faintly encrusted. Pileipellis a tangle of erect hyphae, simple to sparsely diverticulate-nodulose, 2-5 µm diam. Hyphae near the attachment region uniformly long, narrow, 3 µm diam., septate and conspicuously clamped, singly or in clumps. Associated with the host are fine, white, much branched rhizomorphs of uniform, loosely aggregated, hyaline hyphae with conspicuous clamps.

Basidiomes found in quantity on cushions of the umbrella moss Hypnodendron colensoi on the ground in mixed podocarp dicotyledonous forest and associated with fine, white rhizomorphs along the stem of the moss. Fresh basidiomes were found mainly on apparently living moss plants, but adjacent patches of dead moss plants in the cushions were mantled with dark-coloured (dead?) fungal rhizomorphs, suggesting that the fungus could be parasitic. Basidiomes were also found on pieces of dead frond of the fern Diplazium sp. in the moss cushion, attached to more luxuriant rhizomorphs and mycelium.

The New Zealand collection agrees very well with Redhead's (1984) description of Rimbachia bryophila based on North American collections. He also noted evidence from cultural studies (Kühner & Romagnesi 1954) that would indicate that this fungus may be parasitic on mosses. Kühner & Romagnesi also observed it sometimes on vascular plant litter, as with the New Zealand collection, but there was no evidence that it could subsist on that type of substrate far from moss plants. The presence of rhizomorphs in this species is a new feature that does not seem to have been commented on previously. Manimohan & Leelavathy (1988) also observed rhizomorphs in a species they described as being similar to M. bryophilum. M. minutum Manim. & Leelav., from the Eastern Himalayas, growing on living leaves of the moss Homaliodendron montagneanum (Mull. Stuttg.) M. Fleischer.