Gymnopus sp.

The fruitbody is a mushroom, with a cap atop a central stem. Caps range from less than a centimetre to several centimetres in diameter and are convex to flat. They may be smooth or radially fibrillose, dry or slightly viscid, with or without a slight central depression and some species have caps with radial striations or caps with margins  that bend outward slightly (thereby giving the cap a slight flange). The caps come in a variety of colours, commonly white(ish) or brown (from pale brown to reddish brown) and seemingly never in bright colours. Gills are commonly white. Stem colour is often similar to cap colour.     

 There is neither a partial nor a universal veil.

 Spore print: white.

 The species of this cosmopolitan genus are decomposers and the mushrooms are found on humus, forest litter or wood.

 Look-alikes

Gymnopus is probably a common genus in our region but, macroscopically, the mushrooms are often fairly nondescript and a definite identification may require a study of microscopic features. Species of Rhodocollybia produce medium-sized mushrooms that are macroscopically similar to the larger Gymnopus mushrooms, but give a pale yellow to pale pinkish spore print and the spores turn red-brown in a particular iodine solution (Melzers reagent). Neither is the case with Gymnopus. Smaller Gymnopus mushrooms may make one think of Marasmius or Marasmius-like genera.

 Many of the species of Gymnopus and Rhodocollybia were once placed in the genus Collybia. Modern studies of that genus showed it to be quite heterogeneous, which led to many of its species being moved to other genera.

 References

The notes above are based on information given in the following works:

 Antonín, V & Noordeloos, ME. (1997). A monograph of Marasmius, Collybia and related genera in Europe, IHW-Verlag, Eching.

 Cooper, J. (2015). Mycological Notes – 3. Notes on Gymnopus (including Micromphale), Rhodocollybia & Mycetinis (Available at: https://www.funnz.org.nz/sites/default/files/MycNotes31-GymnopusAndAllies_1.pdf)

 Knudsen, H & Vesterholt, J (eds). (2018). Fungi Nordica, Nordsvamp, Copenhagen.