Kaszab Zoltán (szerk.): A Magyar Természettudományi Múzeum évkönyve 70. (Budapest 1978)

Babos, M.: Pluteus studies, I. (Basidiomycetes, Pluteaceae)

ANNALES HISTORICO-NATURALES MUSEI NATIONALIS HUNGARICI Tomus 70. Budapest 1978. Pluteus Studies, I. (Basidiomycetes, Pluteaceae) by M. BABOS, Budapest Abstract — Observations on the variability of a new Pluteus species (P. variabilicolor sp. n.) with a yellow cap. With 7 figures. Although several and well applicable microscopic features also help in the separation of Pluteus species, their identification is occasionally rather difficult. Since usually only one or few fruit bodies appear on the decaying wood substrate, the variability of certain specific characteristics is not sufficiently known. In sites favourable for the fungus, assuring adequate nutrient and water supply (as for instance decaying sawdust heaps), mass appearance of the fruit bodies of several species are known. The reiterated observation of the variability of fruit bodies growing in great numbers and often also in groups, and then collectible in various developmental stages, renders excellent opportunities for the clarification of taxonomic problems. Of primary importance are the observations concerning a Pluteus with a yellow cap when mature, differing from all known species. This rather varying species appeared in masses on a sawdust yard near Szárliget, Vértes Mts., Hungary. My attention was called to the site, producing also great individual numbers of also other rare saprophytic species, by E. VÉssEY, M. VIRÁG, and I. ZIRKELBACH. The same yellow-capped Pluteus was found in smaller numbers on sawdust also in two other localities. Since decaying sawdust affords so much heat and humidity even in the late autumn season that groups or masses of Leucocoprinus species occurring in greenhouses also appear on it, one might have considered even a tropical Pluteus species. The only contrary evidence was its collection some years ago, in one or two specimens, on decaying stumps in forests. Pluteus variabilicolor sp. n. (Figs. 1-7) P i 1 e u s 1.8—7.5—(15) cm in diam.; when young angulately campanuliform or gibbous-convex, convex, later gibbosely explanate or flat; when young mat (duckskin-like), medially rugulose, marginally smooth, later medially more or less rugose-venose, slightly shiny, glabrous, or squamosely to fibrillo-squamosely disrupting and marginally densely striate. When young, its coloration highly divers: yellow with a mustard —• brownish green hue, orange-reddish yellow or lemon yellow, developed pileus citrous or chrome yellow, slightly lighter marginad, scales and fibrillo-scales brownish to greyish brown. — Lamellae emarginate; ( 1.5—)3—

8 mm wide; when young very dense, later close or moderately close; with lamellulae; lamellae fine rosaceous already when young, later carneous; edges white, especially well visible in young fruit bodies, later less conspicuous; no yellow colour observable on lamellae. — Stipe 2.5-10x0.3-1 cm, basally even 2 cm wide; when young slender or squat; cylindrical or clavate, basally bulbous or attenuated; occasionally tubulose; colour white or creamy, when young entire surface often with a brownish black velvet: velvety-punctatefibrillose, on maturing pruinose surface of stipe disintegrating, in some fruit bodies visible only in basal section of stipe, in other specimens stipe entirely whitish to creamy, sericeously shiny, longitudinally fibrous or striped, and the brownish terminal cells discernible only by a lupe. The diverse states can be observed also within a single group of fruit bodies. Basis mycelium white. — Flesh