Agaricus moelleri
Agaricus moelleri, commonly known as the inky mushroom, or dark scaled mushroom, is a large species of fungus in the genus Agaricus. It appears occasionally in most kinds of woodland, during late summer, in northern temperate zones.
Taxonomy
For many years Agaricus moelleri was erroneously accredited with the binomial Agaricus placomyces by some British authors. The epithet placomyces was in fact given to a North American species of Agaricus by Charles Horton Peck in 1878. The current binomial Agaricus moelleri was published in 1976 by the Ukrainian mycologist Solomon P. Wasser.Description
The cap has a greyish-brown patch in the centre and cold grey-brown scaling on the surrounding off-white background. It is in diameter, and yellows when bruised. It is ovate when young, flattening later. The stem has a drooping ring and stains yellow very easily when bruised, this colour then changes to brown over time. The stem flesh bruises yellow only faintly, and is more noticeable in the base. The gills are crowded, and free, as is typical for an Agaricus. They are pink on young specimens, but brown to black on older fruit bodies. The flesh is white and does not change colour on cutting. It smells like ink, iodoform, phenol, sweat, or mouldy straw. The spores are 4–6 x 3–4 μm and are elliptical.Similar species
Agaricus hondensis is similar, with a pinkish tint and firmer flesh.A similar species occurring in North America, Agaricus praeclaresquamosus A.E. Freeman 1979 can grow up to 25 cm wide; it is a possible synonym.
The rare Agaricus phaeolepidotus also has the iodoform, or ink smell, but has browner cap scales, and stains yellow less readily.