Biological Species in Pleurotus
INTERSTERILITY GROUP
ISG I. Pleurotus ostreatus (Jacquin: Fries) P. Kummer.
1871. Der Führer in die Pilzkunde. Zerbst. 146 [105] pp.
European form- Photo by I. Krisai-Greilhuber
European form- Photo by I. Krisai-Greilhuber
Nomenclatural history: Originally described by Jacquin (1774) from Austria, the epithet was adopted by Fries (1821) and is thus sanctioned. Kummer (1871) transferred the epithet from the catch-all genus Agaricus to Pleurotus, which itself had been an infrageneric group within Agaricus (see Fries, 1821).
Typification: Petersen and Krisai-Greilhuber (1996) designated an epitype specimen to supplement the lectotype lithograph by Jacquin (1774). Epitype: AUSTRIA, Vienna, Third District, Hortus Botanicus Vindobonensis, map grid 7864/1, 30.X.94, Tennessee tracking number 6689 (iso-epitypes WU 13683, TENN 53662, K, NY)
Taxonomic history: Although its original circumscription and accompanying illustrations left little doubt about its identity, epitypification and cultures from the epitype collection have secured the identity of the organism and made available tester strains of mating types (see Petersen and Krisai-Greilhuber, 1996).
Basidiomata are commonly collected in Europe, but the name has been used for many morphological variants. The most troublesome has been consistent lack of genetic separation from other morphologically similar taxa, namely (in Europe) P. pulmonarius and (North America) P. "sapidus" (= P. pulmonarius and perhaps P. populinus). The credibility of many published works is questionable due to imprecise circumscription of the taxon used, especially for genetic, physiological, or commercial purposes.
Phenotypic plasticity within the biological species is wide and notorious. In Europe, pileus colors range from deep brown through brown-gray, deep gray, olivaceous deep gray to distinctly bluish or bluish deep gray (variant columbinus). In North America, colors range from pallid tan through medium brown, with one west-coastal population exhibiting gray-black pileus.
Genetic isolation history: Bresinsky et al. (1977, 1987) reported on incompatibility between P. ostreatus and P. pulmonarius, and Ohira (1977) separated putative P. ostreatus from "P. sp." based on incompatibility. Hilber (1982) showed incompatibility of P. ostreatus from all other species tested. Petersen and Hughes (1993) paired four collections of P. ostreatus against 10 collections of P. pulmonarius, two of P. cornucopiae, and four of P. djamor. All interspecific pairings were incompatible. Petersen and Krisai-Greilhuber (1996) confirmed this separation and separation from other Pleurotus species (P. pulmonarius, P. abieticola, P. opuntiae, P. cornucopiae, P. eryngii, P. dryinus, P. djamor, P. populinus, P. purpureo-olivaceus).
Mating system: tetrapolar (viz. Lamoure, 1989, who cites Vandendries, 1923, and Kimura, 1954 as the oldest literature on the subject).
Self-cross: Ohira (1977) furnished a self-cross grid for a Japanese strain (TMI 30056) under the name P. ostreatus. Petersen and Krisai-Greilhuber (1996) used ex epitypus SBIs for a self-cross: AUSTRIA, Vienna, Third District, Hortus Botanicus Vindobonensis, Tennessee tracking number 6689 (WU 13683; TENN 53662). Tester strains: 6689:8 = A1B1; 6689:3 = A2B2; 6689:36 = A1B2; 6689:2 = A2B1. These are available from CBS [Centraalbureau voor Schimmelculturesas] numbers 102510-102513
Anamorphic state: unknown.
Additional information: A color form of P. ostreatus in which the pileus is blue-gray to blue-black, has been given the name P. ostreatus var. columbinus (Quél.) Pilát. Guzmán et al. (1994), based on incompatibility between strains all originally labelled as P. ostreatus but producing basidiomata of two morphologies, adopted P. columbinus (Quél.) Bresadola at species rank. Whether this assignment of names is correct cannot be determined.
Occasional albino basidiomata are produced, and these can be domesticated (Arita, 1974).
Guzmán (1983) reported P. ostreatus from the Yucatan Peninsula, but the accompanying photo almost surely shows P. djamor. Likewise, Guzmán and Garcia Saucedo’s (1973) report of P. ostreatus from Est. Xalapa is suspect, with no supporting documentation given.