Fomitopsis P. Karst., Meddn Soc. Fauna Flora fenn. 6: 9 (1881)


Fomitopsis was established by Karsten (1881) based on four species, with F. pinicola as the generic type (Murrill 1903; Donk 1960). The genus has a cosmopolitan distribution and comprises species causing brown rot on both living and dead trees (Han et al. 2016). Fomitopsis species also contribute to the decomposition of coarse woody debris in forest communities (Gilbertson 1980; Haight et al. 2019). There are certain instances of their pathogenic role in orchards of cultivated species where they cause heart rot on Citrus (Roccotelli et al. 2014) and Prunus species (Adaskaveg 1993). A Fomitopsis sp. was also recorded in oil palm (Elaeis guineensis) as an endophyte (Rungjindamai et al. 2008; Pinruan et al. 2010).

Classification – Basidiomycota, Agaricomycetes, Incertae sedis, Polyporales, Fomitopsidaceae

Type species Fomitopsis pinicola (Sw.) P. Karst.

Distribution – Worldwide

Disease symptoms Fomitopsis causes brown cubical rot on both living and dead trees (Mounce 1929). The basidiospores can be dispersed by wind, or by vectors such as bark beetles (Castello et al. 1976; Pettey and Shaw 1986; Lim et al. 2005; Persson et al. 2011; Jacobsen et al. 2017; Vogel et al. 2017). Upon infecting standing trees, stumps, or logs through wounds, or through the tunnels of penetrating vectors, the fungus establishes itself in the xylem (Mounce 1929). The growth rate of Fomitopsis species in the substrata can differ depending on their ecological requirements (Markovic et al. 2011; Haight et al. 2019). When the decay starts, the wood turns yellowish-brown, which later splits into cubical fragments. The colour is generally lighter in case of F. pinicola than other agents of brown rot decay (Markovic et al. 2011). White mycelial felts can also develop in shrinkage cracks of the decayed wood (Ryvarden and Gilbertson 1993). After establishment, the perennial basidiome appears relatively rapidly (Mounce 1929, Fig. 1). The infection results in the breakage of treetops, or further infection of the base of the trees and weakening of larger roots, which may lead to eventual windthrow of standing trees.

Hosts – The type species, F. pinicola mostly appears on gymnosperms, such as Abies, Larix, Picea and Pinus, but can also be found on angiosperms such as Acer, Alnus, Betula, Carpinus, Corylus, Elaeagnus, Fagus, Fraxinus, Malus, Populus, Prunus, Pyrus, Quercus, Salix, Sorbus, Tilia, Ulmus (Ryvarden and Gilbertson 1993; Dai 2012). The North American species in the Fomitopsis pinicola species complex have also been reported from Pseudotsuga, Sequioa and Tsuga (Haight et al. 2019). Other Fomitopsis species can be found on Ginkgo, Pinus and various angiosperm genera, such as Betula, Castanopsis, Cinamomum, Citrus, Delonix, Fagus, Eucalyptus Ligustrum, Prunus, Quercus and Tilia (Ryvarden and Gilbertson 1993; Dai 2012; Li et al. 2013; Han et al. 2016; Liu et al. 2019).

Morphological based identification and diversity

Based on morphological evidence, over 40 species were accepted in Fomitopsis (e.g. Ryvarden and Johansen 1980; Gilbertson and Ryvarden 1986; Ryvarden and Gilbertson 1993; Núñez and Ryvarden 2001; Hattori 2001). However, phylogenetic studies showed that the morphologically defined Fomitopsis was polyphyletic and taxa clustered with other brown-rot genera in the antrodia clade (Ortiz-Santana et al. 2013; Han et al. 2016). Han et al. (2016) showed that Pilatoporus and Piptoporus are synonyms of Fomitopsis sensu stricto, while the segregation of Rhodofomes was confirmed and five new genera were proposed. Fomitopsis sensu stricto is characterized by annual to perennial, mostly sessile, occasionally effused-reflexed or substipitate, soft, corky, tough to woody basidiocarps, a dimitic hyphal system with clamped generative hyphae and cylindrical to ellipsoid, hyaline, thin-walled, smooth basidiospores which are negative in Melzer’s reagent, and cause brown rot (Fig. 1).

Fig. 1 Fomitopsis pinicola basidiomes on living European spruce, b causing brown-rot decay on narrow-leafed ash, c–d basidiomes on dead standing conifer tree, e young basidiome on hardwood log, f hyphal structure in the trama, g–h basidiospores. Scale bars: f = 20 µm, g–h = 5 µm.


Molecular based identification and diversity

Comprehensive multigene analyses by Han et al. (2016) accepted ten species in Fomitopsis sensu stricto. Two new Fomitopsis species were described from Brazil, F. flabellata and F. roseoalba (Tibpromma et al. 2017). Fomitopsis flabellata was transferred to Rhodofomitopsis and the new combination Fomitopsis bondartsevae was proposed (Soares et al. 2017). Mating studies and molecular phylogenetic analyses resolved four cryptic lineages in the F. pinicola species complex (Haight et al. 2016), that represents three North American species (F. mounceae, F. ochracea and F. schrenkii), and F. pinicola sensu stricto, which is restricted to Eurasia (Ryvarden and Stokland 2008; Haight et al. 2019). Three new species were proposed by Liu et al. (2019) from Australia (F. eucalypticola), Puerto Rico (F. caribensis), and China (F. ginkgonis).

The phylogenetic tree of Fomitopsis presented here is based on analyses of a combined ITS, LSU, tef1 and rpb2 sequence data (Fig 2). In our analyses, it appears that the type of F. bondartsevae is identical to F. iberica and F. hemitephra sensu stricto (Han et al. 2016), which are grouped close to F. palustris and other species formerly discussed in Pilatoporus. Therefore, a thorough revision of the pilatoporus clade is recommended to clarify the status of these species.

Recommended genetic marker (genus level) – LSU

Recommended genetic markers (species level) – ITS, tef1, rpb2

Accepted number of species – There are 104 epithets listed in Index Fungorum (2020). However, only 17 species have DNA sequence data (Table 1).

References – Li et al. (2013) (phylogeny, new species), Han et al. (2016) (phylogeny), Haight et al. 2019 (phylogeny, new species), Floudas et al. (2012) (genome, F. pinicola), Hong et al. (2017) (genome, F. palustris), Liu et al. (2019) (phylogeny, new species).

Table 1 DNA barcodes for accepted species of Fomitopsis. Ex-type/ex-epitype/ex-neotype/ex-lectotype strains are in bold and marked with an asterisk (*). Voucher strains are also in bold.

Species Strain ITS LSU nSSU tef1 rpb2
Fomitopsis betulina Dai 11449 KR605798 KR605737 KR605895 KR610726 KR610816
F. betulina Miettinen 12388 JX109856 JX109856 JX109913 JX109884
F. bondartsevae  X1166* JQ700276 JQ700276
F. cana Dai 9611* JX435776 JX435774 KR605825 KR610660 KR610762
F. cana Cui 6239 JX435777 JX435775 KR605826 KR610661 KR610761
F. caribensis Cui 16871* MK852559 MK860108 MK860124 MK900482 MK900474
F. durescens Overholts 4215* KF937293 KF937295 KR605835
F. durescens O 10796 KF937292 KF937294 KR605834 KR610669 KR610766
F. eucalypticola Cui 16598* MK852562 MK860113 MK860129 MK900484 MK900479
F. eucalypticola Cui 16594 MK852560 MK860110 MK860126 MK900483 MK900476
F. ginkgonis Cui 17170* MK852563 MK860114 MK860130 MK900485 MK900480
F. ginkgonis Cui 17171 MK852564 MK860115 MK860131 MK900486 MK900481
F. hemitephra O 10808 KR605770 KR605709 KR605841 KR610675
F. iberica O 10810 KR605771 KR605710 KR605842 KR610676 KR610771
F. meliae Ryvarden 16893 KR605776 KR605715 KR605849 KR610681 KR610775
F. meliae JV 1109/40-J KY264030
F. mounceae JEH-78* KF169629 KF178354 KF169698
F. mounceae MJL-112-Sp KF169636 KF178361 KF169705
F. nivosa JV 0509/52-X KR605779 KR605718 KR610686 KR610777
F. ochracea JEH-12E KF169597 KF178322 KF169666
F. ochracea JEH-79 KF169604 KF178329 KF169673
F. ostreiformis Miettinen X1393 KC595918 KC595918
F. palustris Cui 7615 KR605780 KR605719 KR610688 KR610779
F. pinicola Cui 10312 KR605781 KR605720 KR605856 KR610689 KR610780
F. pinicola LT-323 KF169651 KF178376 KF169720
F. roseoalba URM 86923* KT189139 KT189141
F. schrenkii JEH-150* KU169365 MK236356 MK208858
F. schrenkii JW18-240-1 KF169648 KF178373 KF169717
F. subtropica Cui 10154* JQ067652 JX435772
F. subtropica Cui 10578 KR605787 KR605726 KR605867 KR610698 KR610791

Fig. 2 Phylogram generated from RAxML analysis based on combined ITS, LSU, nSSU, tef1 and rpb2 sequence data of Fomitopsis species. Related sequences were obtained from GenBank. Thirty-one strains are included in the analyses, which comprised 4143 characters including gaps. The tree was rooted with Daedalea quercina (Dai 12152) and D. dickinsii (Yuan 1090). Tree topology of the ML analysis was similar to the Bayesian analysis. ML bootstrap values ˃50% and BYPP ˃0.80 are shown respectively near the nodes.

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