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The Genus Psathyrella
by Michael Kuo
As I write this in January of 2011, the traditional genus "Psathyrella" is headed for some pretty big changes--so by the time you read this the picture may have changed substantially. For the time being, however, Psathyrella is still a fairly large genus of saprobic gilled mushrooms with dark spore prints (ranging from brown to black or dark purplish gray), "snap-able" stems, and frequently hygrophanous caps (meaning the caps often change color dramatically as they lose moisture, sometimes resulting in two-toned specimens). The gills are neither mottled, nor do they dissolve into black goo when mature. Under the microscope, species of Psathyrella have spores that are brown or dark gray when mounted in KOH and feature smooth walls, as well as an apical pore. The pileipellis is hymeniform or "cellular."
The border line between Psathyrella and Panaeolus has always been confusing, even before contemporary DNA studies (see the linked page for more information), and we are learning that some species of Psathyrella are more closely related to coprinoid mushrooms in the genera Coprinellus and Coprinopsis than they are to some other species of Psathyrella. This cladogram (in Matheny and collaborators, 2006) represents a recent phylogenetic snapshot of the genus (scroll to the Psathyrellaceae clade); for more detailed analyses see Vasutova and collaborators, 2008 (citation below) and Padamsee and collaborators, 2008.
Identification of Psathyrella species is not easy, and generally requires microscope work. Crucial macroscopic features include the disposition of the veil remnants, and the size of the mushrooms. Microscopic features include spore morphology and, especially, the morphology of the hymenial cystidia; a Roman aqueduct section mounted in KOH (2%) is generally sufficient for working with Psathyrella specimens.
In North America over 400 species of Psathyrella have been recorded by Alexander Smith (1972). Many of these, to be honest, represent "species" collected by Smith (often only once) and differentiated on erudite microscopic features--species that may or may not be upheld once someone focuses on the genus on our continent in a contemporary way. Since major species and species groups in North America still largely bear European species names, it is also useful to consult European keys and treatments of the genus (see the reference list below).
Arenal, F., M. Villarreal & F. Esteve-Raventos (2003). Psathyrella albofloccosa, a new species of section Cystopsathra. Mycotaxon 87: 173-177.
Galland, M. C. Kemp, R. F. O. & Jurand, M. K. (1979). The species problem in the Psathyrella candolleana complex. Mycotaxon 8: 329-332.
Guzman, G., L. Montoya-Bello & V. M. Bandala-Munoz (1988). A new species of Psathyrella (Agaricales, Coprinaceae) from Mexico with discussions on the known species. Brittonia 40: 229-234.
Hansen, L. & Knudsen, H., eds. (1992). Nordic macromycetes Vol. 2: Polyporales, Boletales, Agaricales, Russulales. Copenhagen: Nordsvamp. 474 pp.
Kits van Waveren, E. (1971). Notes on the genus Psathyrella--I. Psathyrella gracilis and P. microrrhiza. Persoonia 6: 249-280.
Kits van Waveren, E. (1971). Notes on the genus Psathyrella--II. Three new species of Psathyrella. Persoonia 6: 295-312.
Kits van Waveren, E. (1972). Notes on the genus Psathyrella--III. Unorthodox approach and key to section Atomatae. Persoonia 7: 23-54.
Kits van Waveren, E. (1976). Notes on the genus Psathyrella--IV. Description of and key to the European species of section Psathyrella. Persoonia 8: 345-406.
Kits van Waveren, E. (1977). Notes on the genus Psathyrella--V. The sections Ammophilae, Bipellis and Subatratae. Persoonia 9: 199-231.
Kits van Waveren, E. (1977). Notes on the genus Psathyrella--VI. Four controversial species of Psathyrella: P. fibrillosa, P. frustulenta, P. clivensis, and P. obtusata. Persoonia 9: 281-304.
Kits van Waveren, E. (1980). Checklist of synonyms, varieties and forms of Psathyrella candolleana. Transactions of the British Mycological Society 75: 429-437.
Kits van Waveren, E. (1982). Notes on the genus Psathyrella--VIII. Description and key to the European species of section Hydrophilae. Persoonia 11: 473-508.
Kits van Waveren, E. (1985). The Dutch, French, and British species of Psathyrella. Persoonia Supplement 2: 1-300.
Kits van Waveren, E. (1987). Additions to our monograph of Psathyrella: Thirteen new species, some revised keys, comments on other recently described species, and corrections and additions to our monograph. Persoonia 13: 327-368.
Kits van Waveren, E. (1987). Notes on some British species of Psathyrella. Transactions of the British Mycological Society 89: 420-422.
Larsson, E. & L. Örstadius (2008). Fourteen coprophilous species of Psathyrella identified in the Nordic countries using morphology and nuclear rDNA sequence data. Mycological Research 112: 1165-1185.
McLaughlin, D. J. (1999). Final project report: A search for two rare, endemic Minnesota mushroom species. Downloaded from the Minnesota Department of Natural Resources Web site: http://files.dnr.state.mn.us/eco/nongame/projects/consgrant_reports/1999/1999_mclaughlin.pdf
Moser, M. (1983). Keys to Agarics and Boleti (Polyporales, Boletales, Agaricales, Russulales). Ed. Kibby, G. Transl. Plant, S. London: Roger Phillips. 535 pp.
Nagy, L. G., S. Kocsube, T. Papp & C. Vagvolgyi (2008). Phylogeny and character evolution of the coprinoid mushroom genus Parasola as inferred from LSU and ITS nrDNA sequence data. Persoonia 32: 28-37.
Padamsee, M., P. B. Matheny, B. T. M. Dentinger & D. J. McLaughlin (2008). The mushroom family Psathyrellaceae: Evidence for large-scale polyphyly of the genus Psathyrella. Molecular Phylogenetics and Evolution 46: 415-429.
Smith, A. H. (1972). The North American species of Psathyrella. Memoirs of the New York Botanical Garden 24: 1-633.
Smith, A. H., Smith, H. V. & Weber, N. S. (1979). How to know the gilled mushrooms. Dubuque, Iowa: Wm. C. Brown. 334 pp.
Vasutova, M., V. Antonin & A. Urban (2008). Phylogenetic studies in Psathyrella focusing on sections Pennatae and Spadiceae--new evidence for the paraphyly of the genus. Mycological Research 112: 1153-1164.
Watling, R. & M. Jurand (1971). Two new coprophilous species of Psathyrella. Notes from the Royal Botanic Garden 31: 143-153.
Cite this page as:
Kuo, M. (2011, January). The genus Psathyrella. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/psathyrella.html