RESEARCH ARTICLE Elucidating "lucidum": Distinguishing the diverse laccate Ganoderma species of the United States A. L. Loyd1,2☯*, C. W. Barnes3³, B. W. Held4³, M. J. Schink5³, M. E. Smith6³, J. A. Smith1☯, R. A. Blanchette4☯ 1 University of Florida, School of Forest Resources and Conservation, Gainesville, FL, United States of America, 2 The F.A. Bartlett Tree Experts Company, Charlotte, NC, United States of America, a1111111111 3 Departamento Nacional de Protection Vegetal, INAP, Quito, Ecuador, 4 University of Minnesota, a1111111111 Department of Plant Pathology, St. Paul, MN, United States of America, 5 Independent Researcher, Port a1111111111 Crane, NY, United States of America, 6 University of Florida, Department of Plant Pathology, Gainesville, FL, United States of America a1111111111 a1111111111 ☯ These authors contributed equally to this work. ³ These authors also contributed equally to this work. * [email protected] OPEN ACCESS Abstract Citation: Loyd AL, Barnes CW, Held BW, Schink MJ, Smith ME, Smith JA, et al. (2018) Elucidating Ganoderma is a large, diverse and globally-distributed genus in the Basidiomycota that "lucidum": Distinguishing the diverse laccate includes species causing a white rot form of wood decay on a variety of tree species. For the Ganoderma species of the United States. PLoS past century, many studies of Ganoderma in North America and other regions of the world ONE 13(7): e0199738. https://doi.org/10.1371/ journal.pone.0199738 have used the name G. lucidum sensu lato for any laccate (shiny or varnished) Ganoderma species growing on hardwood trees or substrates. Molecular studies have established that Editor: Minou Nowrousian, Ruhr-Universitat Bochum, GERMANY G. lucidum sensu stricto (Curtis) Karst is native to Europe and some parts of China. To determine the species of the laccate Ganoderma that are present in the United States, we Received: March 30, 2018 studied over 500 collections from recently collected samples and herbarium specimens Accepted: June 13, 2018 from hardwoods, conifers, and monocots. A multilocus phylogeny using ITS, tef1α, rpb1 Published: July 18, 2018 and rpb2 revealed three well-supported clades, similar to previously reported findings. From Copyright: © 2018 Loyd et al. This is an open the U.S. collections, thirteen taxa representing twelve species were identified, including: G. access article distributed under the terms of the curtisii, G. lucidum sensu stricto, G. martinicense, G. oregonense, G. polychromum, G. Creative Commons Attribution License, which ravenelii, G. sessile, G. tsugae, G. tuberculosum, G. cf. weberianum, G. zonatum, and permits unrestricted use, distribution, and reproduction in any medium, provided the original Tomophagus colossus (syn. G. colossus). The species G. meredithiae is synonymized with author and source are credited. G. curtisii, and considered a physiological variant that specializes in decay of pines. The Data Availability Statement: All relevant data are designation G. curtisii f.sp. meredithiae forma specialis nov. is proposed. Species such as within the paper and its Supporting Information G. curtisii and G. sessile, once considered as G. lucidum sensu lato, were found to be diver- files; however, fruiting body collections have been gent from one another, and highly divergent from G. lucidum sensu stricto. Morphological deposited to the University of Florida Mycological characteristics such as context tissue color and features (e.g. melanoid bands), basidio- Herbarium in Gainesville, FL under the accession numbers: FLAS-F-62386 through FLAS-62546. In spore shape and size, geographic location, and host preference were found to aid in species addition, cultures have been deposited to the identification. Surprisingly, G. lucidum sensu stricto was found in the U.S., but only in geo- Center for Forest Mycological Research collection graphically restricted areas of northern Utah and California. These collections appear to in Madison, WI. Futhermore, sequences have been deposited to GenBank, and alignments/trees are have resulted from the introduction of this species into the United States possibly from deposited to www.treebase.com under the mushroom growers producing G. lucidum outdoors. Overall, this study clarifies the chaotic submission accession: 22399. PLOS ONE | https://doi.org/10.1371/journal.pone.0199738 July 18, 2018 1 / 31 The laccate (shiny) Ganoderma species in the United States Funding: This project was funded in part by the F. taxonomy of the laccate Ganoderma in the United States, and will help to remove ambigui- A. Bartlett Tree Experts Company and a research ties from future studies focusing on the North American species of laccate Ganoderma. grant from the International Society of Arboriculture-Florida Chapter and was also supported in part by the USDA National Institute of Food and Agriculture, Hatch project 0022081. Matthew E. Smith's involvement in this project was made possible by the support of the Institute of Introduction Food and Agriculture Sciences at the University of Ganoderma is a genus of wood decay fungi in the Polyporales and Ganodermataceae contain- Florida and by a grant from the National Institute of Food and Agriculture, USDA, under the grant ing species that are commonly observed around the world [1, 2]. The word Ganoderma is #FLAPLP-005289. Finally, the herbarium studies Greek from “Ganoº meaning shiny and ªdermaº meaning skin. Ganoderma was erected as a were made possible by the Clark T. Rogerson genus in 1881 by Karsten and included only one species, G. lucidum (Curtis) Karst [3]. Previ- research award from the Mycological Society of ously, it was characterized as Boletus lucidus Curtis (1781) and then Polyporus lucidus (Curtis) America. The funders had no role in study design, Fr. (1821) [3]. The species P. lucidus was characterized by having a laccate pileus and stipe, data collection and analysis, decision to publish, or which Murrill suspects was the reason for Karsten's division because only one species was preparation of the manuscript. The first author Andrew Loyd is employed by the F.A. Bartlett Tree included, G. lucidum [4]. Patouillard revised Karsten's genus Ganoderma to include all species Experts Company. F.A. Bartlett Tree Experts with pigmented spores, adhering tubes and laccate crusted pilei, which resulted in a total of 48 Company provided support in the form of salary for species classified under the genus Ganoderma in his 1889 monograph [4, 5]. Until Murrill author AL, but did not have any additional role in investigated Ganoderma in North America in 1902, previous work had focused solely on Euro- the study design, data collection and analysis, pean species including G. lucidum, G. resinaceum Boud. (1890) and G. valesiacum Boud. decision to publish, or preparation of the manuscript. The specific role of this author is (1895) [4, 6, 7]. articulated in the `author contributions' section. Murrill described 17 new Ganoderma species in his treatises of North American polypores [4, 7], including G. oregonense Murrill from Picea sitchensis in Oregon, G. sessile Murrill occur- Competing interests: The authors have the following interests: This project was funded in part ring on decaying wood of deciduous trees widespread in the eastern United States (U.S.), G. by the F.A. Bartlett Tree Experts Company. The first tsugae Murrill from decaying trunks, stumps and roots of Tsuga canadensis in the boreal hem- author Andrew Loyd is employed by the F.A. lock forests of the eastern U.S., G. tuberculosum Murrill occurring on dead wood in Central Bartlett Tree Experts Company. There are no America and G. zonatum Murrill from decayed palm wood in Florida [4, 7]. Subsequent patents, products in development or marketed reports on the genus in North America were contradictory, and there was little agreement products to declare. This does not alter our regarding the species designated by Murrill [1, 8±12]. For example, many studies focusing on adherence to all the PLOS ONE policies on sharing data and materials. North American taxa considered G. sessile as a synonym of the European species G. lucidum [8, 11]. This was based on similar fruiting body morphology and host preference for both G. sessile and G. lucidum, in which they were both laccate with reddish-brown crust, with or with- out a stipe, and fruiting on decaying hardwood substrates [7, 8, 11]. Similarly, G. tsugae was also synonymized with G. lucidum, despite the former being described from conifers and the latter from deciduous trees [8]. Atkinson [8] erected G. subperforatum G.F. Atk. in 1908 to include taxa that had ªsmoothº basidiospores, which were due to fine echinulations protruding through the perisporium (hyaline outer wall) of the double-walled basidiospore. Although Atkinson also considered G. tsugae a synonym for G. lucidum [8], Overholts accepted the spe- cies G. tsugae due to its temperate distribution, darker pileus and pure white context tissue [11]. Both Atkinson & Overholts accepted G. curtisii (Berk.) Murrill as a unique species that occurs in more southern latitudes of the U.S. [8, 11]. Although no data were reported, in 1920 in an update on Polyporaceae of North America, Murrill conceded that G. sessile was closely related to the European G. lucidum [13]. It is difficult to determine if this concession was the result of other mycologists' scrutiny or from a scientific foundation, due to the retention of the name by Murrill in a later publication [14] and a single herbarium collection in 1926 (FLAS-F- 08907). In addition, Murrill also described G. sessiliforme Murrill from dead wood in Mexico [15]. The brief description of G. sessiliforme described the fruiting body as similar to G. sessile, but with smaller dimensions. A decade later, Haddow [9] considered G. sessile as a unique taxon, and suggested Atkinson's G. subperforatum was a synonym of G. sessile, on the basis of the ªsmoothº spores compared to the ªroughº spores of G. lucidum, which was the original PLOS ONE | https://doi.org/10.1371/journal.pone.0199738 July 18, 2018 2 / 31 The laccate (shiny) Ganoderma species in the United States basis for G.