Date of Award
Doctor of Philosophy
Ronald H. Petersen
Karen W. Hughes, Randall L. Small, Robert N. Trigiano
The monographic work of Pegler (1983) on Lentinus has established the taxonomic guidelines for most recent studies involving members of the genus (Moncalvo et al. 2002, Rolen 2001, Krüger 2002). Pegler’s taxonomic hierarchy combined both Lentinus Fr. and Panus Fr. into one large genus, Lentinus Fr. The combination of these genera and its validity was one of the reasons for beginning this study. For generic level comparisons, ribosomal DNA sequence data can be helpful for determining relationships among taxa (Binder and Hibbett 2002, Hibbett and Vilgalys 1991, 1993, Hibbett and Donoghue 2001, Moncalvo et al. 2002, Thorn et al. 2000). In this study, ribosomal large subunit (LSU) sequences were used to determine if Lentinus sensu Pegler should contain both Lentinus Fr. and Panus Fr. LSU data were also used to explore the relationships of Lentinus sensu Pegler (1983) to genera affiliated with it in other works (Krüger 2002, Hibbett and Donoghue 2001, Moncalvo et al. 2002). I sought to assess various taxonomic schemes and the delineation of taxa using techniques such as morphology, sexual intercompatibility, and DNA sequence data. In order to determine if ITS data could be useful in elucidating biogeographical patterns, this study concentrated on three morphological species complexes: Lentinus crinitus (Linn.: Fr.) Fr., L tigrinus (Bull.: fr.) Fr., and L. strigosus (Schwein.) Fr. [Panus lecomtei (Fr.) Corner in this study].
The ribosomal ITS1 – 5.8S – ITS2 (ITS) region evolves faster and mutates more frequently than LSU (Hibbett 1992). ITS sequence data was used to study species circumscriptions and delineations among Lentinus sensu Pegler (1983) and its segregates. In some cases ITS sequence patterns can also be used to determine biogeographical patterns (Hughes et al. 1999, Petersen and Bermudes 1992, Petersen 1995a, 1995b).
Lentinus and Panus were found to be separable at the generic level based on LSU sequence data. Several morphological sections (Pegler 1983) of the genera were polyphyletic in maximum parsimony and neighbor-joining analyses (sects. Rigidi, Velutini, and Panus). Group Polyporellus (Nuñez and Ryvarden 1995) was closely related to Lentinus tigrinus and sect. Tigrini (Pegler 1983). Synonymization of L. lindquistii Lechner and Albertó (2000) and L. glabratus under L. tigrinus is suggested. Data also suggests that Panus fragilis O. K. Miller (1965) should be synonymized under P. lecomtei Fr. Lentius suavissimus Fr. is not part of either generic clade containing Lentinus or Panus spp. The transfer of Lentinus suavissimus Fr. to another genus is necessary. A bioegeographical pattern observed in sect. Tigrini showed a correlation between geography and clades based on ITS data. Synonymization of L. lindquistii Lechner and Albertó and L. glabratus Mont. Under L. tigrinus (Bull.: fr.) Fr. is suggested based on sexual intercompatibility studies and molecular data. Polyporus group Polyporellus sensu Nuñez and Ryvarden appears to be a monophyletic group related to Lentinus sect. Tigrini.
This study concentrated on the circumglobal species complex Panus lecomtei Fr. to access biogeographical relationships in that group. Sexual intercompatibility studies indicated that seven collections of this complex formed a cohesive intersterility group. Ribosomal ITS sequence data for all collections of P. lecomtei fr. sampled were nearly 100% identical. Two collections of Panus fragilis O. K. Miller (1965) were also included and found to be conspecific with P. lecomtei Fr. based on ITS and LSU sequence data. Because of the macromorphological similarity of Panus conchatus and P. lecomtei, data from both species were collected. Eight collections of P. conchatus were shown to form an intersterility group. Other species of subg. Panus sensu Pegler (1983) were sequenced for ITS data, but not used for intercompatibility studies. These species include the following: Panus ciliatus Lév. (= Lentinus ciliatus Lév. sensu Pegler 1983), Panus strigellus Berk. (= Lentinus similis Berk. sensu Pegler 1983), Panus fulvus (Berk.) Pegler and Rayner (= Lentinus velutinus sensu Pegler 1983), and Panus similis Berk. and Br. (= Lentinus similis sensu Pegler 1983). Lentinus suavissimus Fr., group Polyporellus (Nuñez and Ryvarden 1995), Ganoderma and Neolentinus Redhead and Ginns (1985) were included to explore possible supra-generic relationships.
Grand, Edward A., "Systematics and species concepts in the genera Lentinus Fr. and Panus Fr., with emphasis on the Lentinus tigrinus, L. crinitus and Panus lecomtei complexes. " PhD diss., University of Tennessee, 2004.