Slender Parasol

Appearance

The fruitbody of ''Macrolepiota clelandii'' has a cap that is initially egg-shaped, later becoming convex and then flattened in maturity, reaching diameters of 7.6–12.5 cm.

It has a dark brown umbo and small dark brown scales that show the whitish flesh underneath. These scales are arranged in concentric rings that become increasingly crowded until the umbo, which is completely covered in scales. Small fragments of the partial veil may be left hanging on the cap margin.

The white gills are free from attachment to the stipe and closely spaced. The slender, hollow stipe measures up to 18.7 cm long, and has a somewhat bulbous base. It has a pale brown colour, and features a ring on its upper half that often detaches to become freely movable up and down the stipe. The mushrooms have no distinctive odour. Its tall stature means the gills are usually clean, having avoided rain splash from the forest floor.

According to Peter Roberts and Shelley Evans, all "parasol" species are edible. Anthony M. Young notes the similarity of ''M. clelandii'' to the edible European species ''M. konradii'', but warns "the toxicity of the Australian species is unknown."

''Macrolepiota clelandii'' produces a white spore print. Individual spores are ellipsoid with a small germ pore, smooth, thick-walled, and measure 13.4–24.8 by 9.6–16.0 µm.

They have a dextrinoid staining reaction with Melzer's reagent. The basidia are club-shaped, measuring 38.0–50 by 10.2–13.6 µm. They are two-, three-, or four-spored, with sterigmata up to 8.0 µm long. Collections with predominantly four-spored basidia will generally have smaller spores than those with two-spored basidia. Two-spored basidia produce spores with four nuclei. Cheilocystidia are plentiful on the edge of the gill. They have dimensions of 24.8–42.4 by 7.2–10.4 µm, with a cylindrical to club shape. There are no cystidia on the gill face . Clamp connections are present in the hyphae.

Naming

The European species ''Macrolepiota konradii'', similar in appearance to ''M. clelandii'', has a smaller range of spore dimensions, typically 13–17 by 8–10 µm. ''M. subcitrophylla'', described from China in 2012, is genetically close to ''M. clelandii''. Unlike the latter species, it has yellow gills. ''M. procera'' is a larger with broad caps up to 12 in in diameter, and the stipe surface is covered with brownish zigzag bands or scaly girdles on a whitish background. Its spores are smaller than those of ''M. konradii'', measuring on average 13.8–15.7 µm. It is now known to occur only in Europe.

The "false parasol", ''Chlorophyllum molybdites'', a toxic species that can be mistaken for ''M. konradii'', also occurs in Australia. It can be distinguished by its green spore print and gills that turn light green in age. Some deadly poisonous ''Lepiota'' species have a similar pattern of scales on the cap, but their fruitbodies are smaller.

Distribution

''Macrolepiota clelandii'' fruits singly or in small groups on the ground in grass or among leaf litter. It is typically found in eucalypt forest and subtropical rainforests.

It has been recorded from Queensland, New South Wales, Victoria, South Australia, and Western Australia. In southwest Australia it is found in jarrah and karri forests, where fruiting usually occurs in late autumn and early winter. The fungus appears to prefer disturbed ground, as it is often found at roadsides by forests, on lawns, grassy areas of parks, and among the slash of thinned karri regrowth forests. It is common in river red gum woodlands. ''M. clelandii'' also occurs in New Zealand, where it is found in mixed mānuka , kānuka , and kauri forest, and in conifer plantations. It is the smallest and most slender of the ''Macrolepiota'' species that occur there.