Material examined.- AUSTRALIA: NSW, Wyong, Watagan State Forest, on rotting leaves in rainforest dominated by Eucalyptus spp., 11 IV 1983, Horak 2181 (SFSU, ZT).- NEW ZEALAND: North Island, Wellington, Butterfly, 22 V 1949, Stevenson 555 (Holotype, K).- South Island, Prov. Westland, between Kumara and Mitchells, 9 III 1968, Horak 68-116 (SFSU, ZT).

Pileus 8-30 mm diam, hemispherical with incurved margin when young, expanding with age to convex, broadly convex or plano-convex, with or without ; a broadly obtuse umbo, non-striate; surface dull, dry, minutely velutinous; orangish brown overall when young, fading towards the margin in age. Context membranaceous, thin, white to pale orange.- Lamellae adnate to subemarginate, close (23-28) with 2-3 series of lamellulae, often anastomosing, moderately broad (1-2 mm), white at first changing to cream with age; edges even, concolorous.- Stipe 20-45 x 1-2 mm, central, terete, equal or gradually tapering towards the base, dull, dry, tough, fistulose, minutely pruinose (at least in upper portion), non-insititious, base attached to substrate with white or yellowish mycelial strands; cream to orange or orangish brown at the apex, grading to fuscous below; context brown at the base.- Odor and taste not distinctive.
Basidiospores (7.0)7.5-9.0 x 3.0-3.5(-4.0) µm, narrowly ellipsoid, sometimes curved in profile, smooth, thin-walled, hyaline, inamyloid. - Basidia 20-24 x 5-6 µm, cylindrical to subclavate, 4-spored, clamped.- Cheilocystidia common, of Siccus-type cells; main body 10-20 x 5-9 µm , polymorphic, subclavate to broadly clavate or irregular in outline, hyaline to yellowish, thin-walled; apical setulae 2-12 x 0.5-1.0 µm, cylindrical, hyaline.- Pleurocystidia absent.- Pileipellis hymeniform, not mottled, composed of Siccus-type cells; main body 14-25 x 5-10 µm, cylindrical to clavate, yellowish brown, base thin-walled, apex moderately thick-walled (up to 0.5 mm); apical setulae 3-20 x 1 µm , cylindrical to needle-like, thick-walled to solid, yellowish brown.- Pileal and lamellar trama dextrinoid. - Stipe tissue monomitic; cortical hyphae cylindrical, orangish brown, dextrinoid.- Caulocystidia common, of Siccus-type cells; main body 10-20 x 4-8 µm , polymorphic, hyaline to pale yellow, thin-walled to moderately thick-walled, with few to numerous apical setulae 5-30 x 1-2 µm, narrowly conical to needle-like.- Clamp connections present.

Habit, habitat and distribution.-Solitary, in groups on Nothofagus litter (holotype), or on leaf litter in forests dominated by Dacrydium, Quintinia and Weinmannia (Nothofagus absent). Australia, New Zealand.

Marasmius croceus is characterized by a smooth, orangish brown to bright saffron pileus, close, broad, non-marginate lamellae, a pruinose, orangish brown stipe, relatively small basidiospores, no pleurocystidia, and Siccus-type pileipellis cells and caulocystidia with long setulae. The species belongs in sect. Sicci series Leonini, where it is allied with M. leoninus Berk., M. abundans var. abundans Corner and M. sullivantii Mont. Marasmius leoninus, from South America, differs in forming a sulcate to deeply furrowed pileus, subdistant lamellae (12-16), a mottled pileipellis with numerous unpigmented cells, and more reduced caulocystidia (Holotype, K!). Marasmius abundans, from Malaya, differs in forming a sulcate-striate pileus, fewer lamellae (14-22), a glabrous stipe lacking caulocystidia, and larger basidiospores measuring 10-13 x 3-4 µm (fide Corner, 1996). Marasmius sullivantii from eastern North America, differs in forming a deep reddish brown to orangish red pileus, numerous fusoid pleurocystidia, cheilocystidia and pileipellis cells with shorter setulae (2.5-8.0 µm), and two types of caulocystidia (Holotype, PC!). Marasmius croceus is also similar to the Australian species Marasmius elegans (Cleland) Desjardin & E. Horak, comb. nov. [Basionym: Collybia elegans Cleland, Trans. Royal Soc. S. Australia 57: 187. 1933. Holotype: Mt. Lofty, AD #3788]. The latter species differs, however, in forming larger basidiospores (10.5-13.0 x 4.5-6.0 µm), pileipellis cells with shorter setulae (2-8 µm long), and irregularly cylindrical, thick-walled caulocystidia instead of Siccus-type caulocystidia (Holotype, AD!).

[Notes from Kew Type specimen, PRJ 2010] Kew images.

Pileus 1-2 cm diam., bright saffron, velvety, plano-convex with down rolled margin; flesh thin, whitish. Gills adnexed to adnate, moderately close, whitish. Stipe 1.5-2.5 cm x 1-2 mm, cream above, orange below, velvety, tough, solid, sometimes tapering at base. Spores 8-10 x 3-4 µm non-amyloid, thin-walled; gill edge with many cystidia like broom-cells or small awl-shaped cells, 10 x 1-2 µm. Cuticle of pseudo-amyloid broom-cells and awl-shaped cells, 10 x 1-3 µm.

In Nothofagus litter, Butterfly, Wellington, 22.5.1959, Stevenson (type).

Pileus 1-2 cm diam., laete croceus, velutinus, plano-convexus, margine deorsum revoluto; came tenui albida. Lamellae adnexae usque adnatae, modice confertae, albidae. Stipes 1.5-2.5 cm x 1-2 mm, superne cremeus, inferne aurantiacus, velutinus, tenax, solidus, basi interdum attenuatus. Sporae 8-10 x 3-4 µm haud amyloideae, parietibus tenuibus; lamellarum acies cellulis multis scopiformibus cystidioideis vel cellulis parvis subuliformibus 10 x 1-2 µm instructa. Cuticula e cellulis, scopiformibus pseudo-amyloideis et cellulis subuliformibus 10 x 1-3 µm sistens.

Typus: Stevenson 555.