Material Examined Watagan State Forest, NSW, 10.v.1982, A.E. Wood, UNSW 82/271; Monga State Forest, NSW, 18.v.1983, A.E. Wood, UNSW 83/771(a); Megalong Valley, NSW, 19.6.1983, H. Ramsey, UNSW 83/948; Blackheath, NSW, 23.vi.1983, A.E. Wood, UNSW 83/987; Blackheath, NSW, 23.vi.1983, A.E. Wood, UNSW 83/988; Bola Creek, NSW, 7.vii.1983, F. Taeker, UNSW 83/1052; Monga State Forest, NSW, 16.v.1984, A.E. Wood & N B. Gartrell, UNSW 84/539; Mt. Wilson, NSW, 26.iii.1988, A.E. Wood, UNSW 88/17; Lake Rotoiti, NZ, 29.iv.1968, E. Horak, PDD 27088 (holotype).

Pileus (6)10-20 mm, convex (occasionally slightly umbonate), expanding to plano-convex; smooth, dry, apricot-yellow to light orange (9J7-9I11, M&P), usually darker at the centre, all parts fading with age; red tints completely absent; a little pellucid striate if moist, especially towards the margins; margins usually slightly crenulate, especially when young. Lamellae adnate-arcuate to usually subdecurrent; occasionally anastomosing; not especially thick, widely spaced to distant, very frequently connected by veins on the undersurface of the pileus; pallid apricot or pileus tinted, margins concolorous. Stipe 17-44 x 1.5-3.5 mm, cylindrical but often tapers towards the base, smooth, dry, hollow, pale apricot-yellow to similar to pileus but paler at the base to near white.
Spores (3.5)4.0-6.5 x 3.5-4.5(5.0) µm, mean 5.2 x 4.2 pm, Q: 1.0-1.6, mean Q: 1.2-1.3, mostly subglobose but occasionally sublacrymoid, smooth, hyaline, non-amyloid. Basidia 30-41(42.5) x 4.5-7(8) µm, mean 34 x 6 µm, Q: 4.4-7.5, mean Q: 5.7, 4-spored (occasional 2-spored forms exist, see discussion below), clamped, sometimes with medallion clamps. R: 6.5. Cystidia absent. Hymenophoral trama subregular to irregular, composed of hyaline, thin-walled, septate, semi-inflated, at least partially interwoven hyphae 20-90(120) x 3-12(15) µm, frequently constricted at the septa and often with medallion clamps. Pileipellis a cutis, (often some hyphae partially gelatinise to give the appearance of an ixocutis, but fresh material is not viscid), cuticular hyphae 1-3 µm diameter, clamped, forming a repent layer 20-40 µm deep overlying a subpellicular layer of hyaline, clamped, inflated cells 40-80 x 6-12 µm, cuticular pigment plasmatic and also as granules on the hyphal walls. Stipitipellis a cutis of hyaline, thin-walled, inflated, clamped hyphae 2-4 µm, sometimes overlain with a loose layer of extensively branched, thin-walled, clamped hyphae 3-8 µm; subpellis an array of inflated, thin-walled, hyaline, clamped, parallel elements 6-11 µm.

Gregarious on soil in rainforest.

Remarks This New Zealand species is present in Tasmania (Fuhrer and Robinson 1992) and New South Wales. It is close to the New Zealand species Hygrocybe apricosa Horak but that taxon has spores which are ellipsoid (4-5 x 2-2.5 µm), has no cuticular layer of thin hyphae, and is deep apricot-orange. Herbarium material of aurantiopallens is always a dull orange and the cross veins can readily be seen on the pileus undersurface. Some collections of aurantiopallens contain large numbers of 2-spored basidia which do not significantly differ from the dimensions of 4-spored basidia but which do produce larger spores (5.5-7(8) x 4.5-6 µm; mean: 6.3 x 5.1 µm). Both spore ranges can be found on the same basidiome and apart from the 2-spored basidia; there are no other significant differences.