The North American species of Psathyrella.

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MEMOIRS OF THE NEW YORK BOTANICAL GARDEN

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Observations. This species is closely related to P. subhyalinispora but has
distinctly larger spores and yellower colors for the pileus when young. Psathyrella
luteopallida is close to P. gordoni (Berk. & Br.) Dennis & Pearson, but the
latter has a darkening stipe base.
Psathyrella subg. Pannucia (Karsten) A. H. Smith, comb. nov.
Pannucia Karsten, Bidr. Finl. Nat. Folk 32: 512. 1879.
Drosophila subg. Pannucia (Karst.) Romagnesi, Bull. Soc. Linn. Lyon 13: 52. 1944.
Psathyrella subg. Pannucia (Karst.) Romagnesi (in Singer, Lilloa 22: 469. 1951).
(Apparently Romagnesi never used the name in combination with Psathyrella.)
Psathyrella subg. Psathyra (Fr.) Singer, Agar. Modern Taxon. 510, 1962. This
combination was apparently not validly published.
In this group, as emended, I have placed those species with a moderately
to well-developed partial veil typically appendiculate on the margin of the
young pileus for a time after it breaks, and in which pleurocystidia are present.
It should be kept in mind, however, that, in addition to the partial veil, an outer
veil may be present in various degrees of development depending on the species.
Also in this subgenus, and recognized as the type section, Pannucia, the outer
veil is well developed but the inner veil is more fibrillose than membranous.
It is the remains of the outer veil which, for the most part, cause the pileus
margin to be appendiculate at first in some species of this section. As indicated
in the key, the pleurocystidia are not of the type which characterize subg.
Homophron. However, in Pannucia, one finds species with slightly thickened
cystidial walls (0.5 p). An annulus may accidentially be present on an occasional
basidiocarp, but this is too infrequent to cause any real difficulty in identifying
collections.
Type. Psathyrella fibrillosa.
Key to the Sections of Subgenus Pannucia
1. Pileus margin appendiculate for a time from remains of a typically submembranous
to membranous inner veil. sect. Appendiculatae.
1. Pileus when young showing a well developed outer veil leaving copius remains
that may fringe the margin at first; inner veil more or less fibrillose. sect. Pannucia.
Section Appendiculatae A. H. Smith, sect. nov.
Pileus ad marginem appendiculatus, glabrescens.
Type. Psathyrella piceicola.
The name Pseudo-Hypholoma Konrad & Maublanc, Encyc. Mycol. 14: 125.
1948 for a section of Psathyrella was not validly published. I have considered
it desirable to avoid reference to the name Hypholoma as much as possible in
this work and so propose a name that features the distinguishing character of
the section.
Key to the Subsections of Section Appendiculatae
1. Spores 9-12 X 6 u or larger. subsect. Appendiculatae.
1. Spores smaller. 2
2. Spores 5-7 1, long (if 6.5-8 u see next choice) subsect. Hydrophilae.
2. Spores 7-10 X 4-5 A. 3
3. Pleurocystidia utriform or fusoid-ventricose and with the apex broadly rounded.
subsect. Largae.
3. Pleurocystidia nine-pin-shaped to obtuse to acute. subsect. Subacutae.