Pileus usque ad 3 mm latus, minutus, convexus subcupuliformis, albus, velutinus vel minute substrigosus, siccus. Lamellae rarae, subvenosae vel nullae, hymenium glabrum, album, velutinosum. Stipes usque ad 10 X ad 0.2 mm, centralis, cylindricus, apicaliter albidus, basin versus niger, ad apicem pruinosus, deorsum levis, siccus, tenax. Inodorus. Basidiosporae 6-7.5 X 2.5-3 µm, subellipticae vel virguliformes. leves, hyalinae, inamyloideae. Basidia 15-20 X 5 µm, tetrasporica, fibulata. Cystidia hymeniales rara, 30-50 X 5-6 µm, fusiformia apice subglobosa (up to 6 µm diam.), tenuitunicata, hyalina. Pileipellis hymeniformis e cellulis clavatis vel subfusiformibus, 15-30 X 8-15 µm, dense diverticulata tenuitunicata, hyalina. Pilocystidia numerosa, 35-45 X 7-12 µm, cystidiis hymeniales similia. Caulocystidia rara, 15-25 X 5-7 µm, cystidiis hymenialibus similia. Ad folia putrida Nothofagi cliffortioides. Novazelandia. PDD, holotypus.

On rotten leaves of Nothofagus solandri var. cliffortioides (Hook. f.) Poole. Known from South Island of New Zealand.

Pileus to 3 mm diam., at first convex, becoming flat-expanded, finally saucer-shaped with upturned margin, white, velutinous to minutely hairy-strigose (under hand-lens), dry, very fragile. Lamellae none, hymenophore smooth or exceptionally with very low venose folds, white, velutinous under hand-lens. Stipe to 10 X to 0.2 mm, central, cylindrical, horsehair-like, apex whitish, lower 3/4 black, apex minutely pruinose, otherwise glabrous, dry, solid, elastic, solitary in groups, insititious (basal disc or byssus absent). Odour absent. Basidiospores 6-7.5 X 2.5-3 µm, slender-elliptic with attenuated base or comma-shaped, smooth, hyaline, inamyloid. Basidia 15-20 X 5 µm, tetrasporic, cylindric to subclavate, sterigmata up to 2 µm long, clamped. Hymenial cystidia scattered, 30-50 X 5-6 µm, fusiform with subglobose apex (up to 6 µm diam.), thin-walled, hyaline. Pileipellis hymeniform, composed of clavate, subfusiform or irregularly shaped broom-cells, 15-30 X 8-15 µm, setulae wart-like or short cylindric (1-4 X 0.5-1 µm), non-gelatinous, thin-walled, hyaline, occasionally with brown intraparietal or encrusting pigment (in KOH), clamped. Pilocystidia numerous, 35-45 X 7-12 µm, apex 5-7 µm diam., shape and structure as hymenial cystidia. Oleiferous hyphae absent. Stipe tissue monomitic. Stipe cortical hyphae cylindric, 3-6 mm diam., parallel, with dark brown intraparietal and/or encrusting pigment, weakly dextrinoid in stipe apex. Caulocystidia scattered, 15-25 X 5-7 µm, shape and structure as hymenial cystidia.

Marasmius meridionalis belongs in sect. Epiphylli subsect. Eufoliatini Singer (1976). It is characterised by forming very small basidiomes with smooth hymenophores, fructifications on leaves of Nothofagus, small basidiospores, weakly dextrinoid tissue in the stipe apex, and a pileipellis composed of setulose cells plus capitate pilocystidia. Marasmius meridionalis differs from all other taxa in the section in the combination of a smooth hymenophore and setulose pileipellis cells. The European M. epiphylloides (Rea) Saccardo & Sydow is similar in some respects, but differs in forming well-developed lamellae, fructifications on leaves of Hedera, and in having thick-walled pilocystidia, inamyloid stipe tissues, and basidiospores 11-15 µm long

Holotype: New Zealand, Canterbury, Ashley, Mt Grey, Kowai River Reserve, 10.xii.l968, Horak (PDD; ZT 68-681, isotype).