Rare Species Guide

  Basis for Listing

Psathyrella cystidiosa is rare mushroom endemic to Minnesota. It was first reported in Minneapolis in 1912, but was not collected again until 1998 when it was found as part of a DNR-sponsored mushroom survey (McLaughlin 1998). So far, collections have been made in Rice and Washington counties, although specimens have only been found once in each county and only in small groups. Psathyrellas are associated with the cycling of organic matter, such as wood, leaf litter or dung, and may occur in or outside woods. Psathyrella cystidiosa was listed as an endangered species in Minnesota in 1996.

  Description

Psathyrella cystidiosa is difficult to recognize in the field. The cap can grow up to 30 mm (1.2 in.) broad. It has concentric zones of color from light yellowish brown at the center to deep yellowish brown towards the edge. The white stalk is 16-50 mm (0.63-2.0 in.) long and 1-3 mm (0.04-0.12 in.) wide. It has a dark grayish brown spore print. Microscopically this species can be distinguished from other similar looking species by its thick-walled cystidia, a sterile structure found on the face of the gills. Psathyrella cystidiosa is most similar to P. olympiana both microscopically and macroscopically, but can be separated statistically by measuring the apical wall of the cystidia: the wall at the apex of the cystidia is thicker in P. cystidiosa (Padamsee 2001).

  Habitat

The original description of P. cystidiosa mentioned only that it had been found with a ball of soil attached to the base. The two recent collections were found on the ground and also scattered along a dead branch on the ground. Both were found in deciduous forests. The mushroom occurs in shade and may have a preference for thoroughly moistened areas prior to fruiting.

  Biology / Life History

Not much is known about the biology of P. cystidiosa. It is a saprotroph and is usually found in small groups or scattered. The species is found in moist soil or attached to dead branches of deciduous trees. A search for this mushroom in the same location conducted one year after the specimens were found (McLaughlin 1999) did not find this species, but it was discovered at a different location during that same year, indicating that P. cystidiosa may not fruit every year. This species is likely dispersed in the form of mycelia (thread-like structures that make up the body of a fungus) and spores. Low nutrient availability probably triggers the growth of the mushroom in this species. The earliest documentation of this species is the 12th of June and the latest is the 12th of August. Because this species has only been reported three times, it is difficult to specify its life history. Further studies about P. cystidiosa should reveal more information about its biology.

  Conservation / Management

Psathyrella cystidiosa seems to prefer moist soil, but the soil does not need to be continuously wet. It is found in soil or attached to dead branches, thus removal of dead wood from the forest floor would likely threaten this species. This species was also found among relatively immature trees.

Based on previous collections, the best time to search for this mushroom in Minnesota is from early June through mid-August.

  Conservation Efforts in Minnesota

Twenty collecting trips have resulted in two collections of P. cystidiosa. Four counties have been examined with focused searches in Nerstrand Woods State Park, Afton State Park, Wolsfeld Woods Scientific and Natural Area, Belwyn Educational Center, and the Minnesota Valley National Wildlife Refuge. Extensive research has been conducted on the separation of P. cystidiosa from P. olympiana (Padamsee 2001; Padamsee et al. 2008).

  References and Additional Information

McLaughlin, D. J. 1998. A search for three rare, endemic Minnesota mushroom species. Final report submitted to the Natural Heritage and Nongame Research Program, Minnesota Department of Natural Resources. 5 pp.

McLaughlin, D. J. 1999. A search for two rare, endemic Minnesota mushroom species. Final report submitted to the Natural Heritage and Nongame Research Program, Minnesota Department of Natural Resources. 3 pp.

Padamsee, M. 2001. A biogeographic and systematic study of certain Minnesotan Psathyrella species. Thesis, University of Minnesota, St. Paul, Minnesota. 74 pp.

Padamsee, M., P. B. Matheny, B. T. M. Dentinger, and 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.