The North American Species of Pholiota
Subgenus Hygrotrama subg. nov.
Pileus glaber vel subfibrillosus, udus, hygrophanus vel subhygrophanus, non-viscidus. Typus: Pholiota subangularis.
Key to Sections
|1. Spores with wall less than 0.5 µ thick (usually less than 0.25 µ thick).||
|1. Spores with wall 0.5 µ thick or more||
Phaeomarasmius section Confragosi Singer, Sydowia 15: 75. 1962.
In this group are placed species with a non-viscid moist and more or less hygrophanous pileus which is glabrous except possibly for some superficial veil remnants or is canescent at first. Pleurocystidia are absent or inconspicuous, if present they are not the type known as chrysocystidia. If the pileus is viscid or has gelatinized subcutis and pleurocystidia are absent to inconspicuous see subgenus Hemipholiota.
Key to Species
|1. Clavate-rostrate pleurocystidia scattered in the hymenium|
|1. Pleurocystidia present as pseudocystidia or subcapitate or absent||
|2. Growing on charred wood; pileus dark red|
|2. Not as above||
|3. Pleurocystidia present and mostly capitate|
|3. Pleurocystidia absent|
The species placed here shows thicker spore walls than occur in other stirps when spores of the same size are compared. The apical pore is obscure in some spores. This is the genus Pachylepyrium of Singer, who states (1963, p. 559) that the genus differs from Kuehneromyces in the color of the spores and the character of the surface of the pileus and in habitat. We do not agree that the degree of thickening in the spore wall is of any generic significance here since throughout the genus the spore wall is not what one would term thin in the sense that the term applies to the Tricholomataceae. To us the situation is more like that found by Smith (Smith & Zeller, 1966) in Rhizopogon. In this genus the spore wall varies from thin up to 0.5 up thick (which is scarcely to be regarded as thin), but Morten Lange found one species with spore walls up to or over 1.5 µ thick. As to spore color, it is within the range of that of subg. Pholiota. Hence there is no use trying to use either of these characters to establish a genus in this complex. In the absence of E M photographs of the spores of Pholiota in general it is premature to use the number of layers in the wall as a generic character here. In all of the stirpes so far discussed for this subgenus the spores approach those of P. subangularis in wall thickness. We have one species known to date in North America: P. subangularis.
Key to Species
|1. Only one species|