Biological Species in Pleurotus
ISG X. Pleurotus tuber-regium (Fries) Singer.
1951. Lilloa 22: 271. 1951. Lilloa 22: 271.
Nomenclatural history: Rumph (1750: pl. 57/4) used a polynomial to represent the organism. Fries (1821: 174) adopted the name of the basidioma under Agaricus, thus sanctioning it against all other synonyms, but because of Rumph’s illustration, Fries included the epithet under tribe Omphaliae, subtribe Lentiscyphi. Fries used the name Pachyma tuber-regium for the sclerotium, but later recognized that the basidioma and sclerotium were together. Later (Fries, 1836: 392-393), he recombined the epithet into Lentinus. In both sources, however, Fries indicated that he had seen only an illustration (by Rumph). In 1821, "v.ic.;" in 1836, "non vidi." Saccardo (Syll. Fung. 4: 604) left placement of the epithet in Lentinus, but Singer recombined it into Pleurotus. Pegler (1983) included it as a species of Lentinus. The most complete literature on the species has come from Nigeria, where P. tuberregium sclerotia and basidiomata are eaten, and an attempt is being made to commercialize the fungus. See Oso, 1977, for early literature, and Okhuoya et, 1998, Nwokolo, 1983, and Isikhuemhen and Okhuoya, 1996, for more recent applied research.
Typification (to our knowledge, no holo- lecto- or neotype specimen has been designated, but the illustration by Rumph could serve as a lectotype. Location, teste Rumph, Fries, Saccardo): Molucca Islands, Oma, Goroma, Ternata, IV, X.
Taxonomic history: P. tuber-regium is the only Pleurotus taxon in which basidiomata arise from a sclerotium, to which the epithet refers. Lentinus tephroleucus produces similar (but lamellate) basidiomata from a pseudosclerotium (viz. Pegler, 1983) and an unidentified subtropical American Lentinus produces dark brown basidiomata with very deep purple lamellae from a true sclerotium. Unlike cultures of Lentinus, however, cultures of P. tuber-regium produce microdroplets diagnostic for Pleurotus.
See Pegler (1983: 193) for a list of synonymous names, including those coined by Fries. Pegler’s placement of the spies in Lentinus, however, may raise questions about synonymy.
Genetic isolation history: Petersen (unpubl. data) has paired monokaryon isolates of DSH92-155 (see below) against the complete battery of tester strains cited here, with total incompatibility. Thus, the species was judged to be a discrete genetic unit.
Self-cross (see Petersen et al., 1997): PAPUA NEW GUINEA, Mandang Prov., Amron, X.92, coll. D. Hibbett, no. 92-155 (cf. Hibbett & Thorn, 1994), SBIs from in vitro fruited basidiomata donated by Dr. Greg Thorn. Tester strains: DSH92-155:1 = A1B1; DSH92-155:4 = A2B2; DSH92-155:3 = A1B2; DSH92-155:6 = A2B1.
Anamorphic state: unknown.
Isikhuemhen, O.S., J-M. Moncalvo, F. Nerud, and R. Vilgalys. 2000. Mating compatibility and phylogeography in Pleurotus tuberregium. Mycol. Res. 104: 732-737.