Ossicaulis semiocculta
Ossicaulis semiocculta is a small wood-rotting mushroom species. It was originally described by John Burton Cleland in 1927 as Cliyocybe semiocculta. It was transferred to the genus Ossicaulis by Jerry A. Cooper in 2023.
Description
Pileus 1.2 to 6.2 cm diameter, at first slightly convex with down turned edge, then sometimes expanded and upturned, often depressed over the attachment of the stem, wavy, irregular and more or less lobed at the margin, when found growing usually whitish to dingy whitish or pale buffy white or creamy white and opaque, smooth, a little translucent when very moist, when gathered becoming Ochraceous Buff round the edge and even browner in the centre, herbarium specimens drying a dingy biscuit colour. Gills adnate to sometimes slightly decurrent, close, narrow, whitish, then creamy-white. Stem short, 1.2 to 2.5 cm, central to excentric or occasionally almost lateral from the position in which it may have grown, similarly often bent, slender or rather stout, equal or slightly attenuated downwards, pruinose, tough, hollow above, the colour of the pileus. Flesh thin, equally attenuated outwards. Spores nearly subspherical, 3.5 to 4 x 2.5 to 2.8 μm, 4 μm. Sometimes caespitose. Attached by fluffy-white mycelium to the undersides of thick sheets of fallen or stripped bark and fallen wood on the ground beneath eucalypts, or around the base of stumps, the pilei often emerging with difficulty or only found after removing overlying litter. Cleland used Ridgeway colour standard and nomenclature.Range
South-eastern Australia south Western Australia and Tasmania. New Zealand.Habitat
Eucalyptus forest in Australia. In New Zealand recorded on tree ferns, gymnosperms. monocotyledons, and dicotyledons.Ecology
Growing on decomposing wood. In New Zealand recorded on dead and decaying tree fern fronds, and fibrous monocotyledon leaf and stem material.Etymology
From Latin, semi, half; occult us, hidden. The specific name alludes to the frequency with which the mushrooms are often more or less hidden under bark and debris.Taxonomy
For current taxonomic relationship of the genus see Ossicaulis. As Cliyocybe semiocculta the pale colouration of the pileus, the adnate to slightly decurrent gills, the presence of clamp connections and the absence of cystidia indicate it belongs in Subgenus Clitocybe, Section Disciformes.Molecular genetics analysis suggests that Ossicaulis is most closely related to the genera Asterophora, Hypsizygus, Lyophyllum, and Tricholomella.