The North American species of Psathyrella.

1972]

PSATHYRELLA

61

instances, however, the host fungus is very likely a mycorrhiza former, and in
the case of Boletus parasiticus the parasite is no doubt derived from ancestral
types which were mycorrhiza formers. Nyctalis species parasitize species of
Russulaceae but here there are indications that the basidiocarp of the parasite
has undergone distinct evolutionary changes possibly as the result of its parasitic
habit. There seems to be no indication that the parasites were at first mycorrhiza
formers, or that they reached their present habit starting from such a relationship.
Apparently the valid combination in Psathyrella has not been made previously.
Material examined. Michigan: Bonner 8-13-12; Goodwin 10-18-10; Taylor
9-?-10; Smith 21231, 63606, 67731, 67792, 72888, 9-11-38; D. E. Smith 10-14-62.
Psathyrella subg. Pseudostropharia A. H. Smith, subg. nov.
Stipes annulatus; annulus membraneus vel floccosus et crassus, persistens vel
evanescens. Typus. Psathyrella caputmedusae.
Observations. This subgenus features a level of veil development in two
distinct (for this genus) lines of evolution. The texture of the veil is sufficiently
firm and coherent so that when the pileus expands it breaks at the margin of
the pileus thus leaving an annulus on the stipe most of the time. The outer
veil if one is present, is not innate and colored as in subg. Psathyroides but some
intermediates occur, see P. pseudocotonea. Remains of the outer veil may
persist longer on the stipe below the annulus than on the pileus or none may
be present to begin with-it depends on the species.
Species in other subgenera may produce annulate basidiocarps occasionally,
usually one or two in a cluster of otherwise non-annulate individuals. In North
America this is particularly evident in subg. Pannucia sect. Appendiculatae,
especially the stirps Candolleana. The second most likely place to encounter
annulate variants is in subg. Pannucia sect. Pannucia where there is generally
rather pronounced development of the veil. Again, however, only one or a few
basidiocarps out of a good sized collection will be annulate. In Lacrymaria and
Psathyroides annulate basidiocarps are more numerous, especially during good
seasons, but it should be noted that in the key to subgenera these are keyed out
before Pseudostropharia.
In spite of diligent search I have not found the type of section Spintrigerae
in North America. It should be a beech-associated dark brown species lacking
pleurocystidia. Psathyrella kauffmanii is perhaps closest, but features broadly
rounded pleurocystidia. In the Pacific Northwest, P. longistriata is our most
common species for this subgenus. It needs further study since as presented
here it encompasses a large amount of variation. P. caputmedusae is an example
of a strikingly distinct but rare species occurring on wood of conifers in both
Europe and North America.
Key to the Sections of Subgenus Pseudostropharia
1. Pleurocystidia present. Pseudostropharia.
1. Pleurocystidia absent. Spintrigerae.
Section Pseudostropharia
See Psathyrella carbonicola and other members of subg. Pannucia sect.
Appendiculatae also.