Ganoderma sichuanense (Ganodermataceae) is a medicinal mushroom originally described from China and previously confused with G. lucidum. It has been widely used as traditional medicine in Asia since it has potential nutritional and therapeutic values. We collected 8 specimens of Ganoderma species from Thailand and show that they represent the first record of G. sichuanenese for Thailand. In this paper, we describe our specimens of Ganoderma sichuanense based on fresh basidiomes, and provide line drawings and photographs. The data from macro- and microscopic features are consistent with the characteristics of the species. Analysis of ITS sequence data indicates that the Thai collections cluster in same species clade as the epitype of G. sichuanense.

Ganoderma lingzhi , Ganoderma lucidum , Phylogeny, Taxonomy

The genus Ganoderma was established by Karsten (1881) based on Ganoderma lucidum (Curtis) P. Karst. The genus Ganoderma includes the subgenera Ganoderma (which in turn includes sections Ganoderma and Phaenema), Elfvingia, and Trachyderma (Zhao and Zhang 2000). Many members of this genus are found in subtropical and tropical regions and appear to thrive in hot and humid conditions (Pilotti et al. 2004). Ganoderma species grow as facultative parasites of trees but can also live as saprobes on rotting stumps and roots (Turner 1981, Pilotti 2005). Basidiomes are commonly in the form of a bracket (Pilotti et al. 2004). Bioactive compounds from Ganoderma show a huge structural and chemical diversity (Deepalakshmi and Mirunalini 2011). These bioactive constituents are reported to be responsible for anti-cancer, anti-inflammatory, anti-tumor, anti-oxidant, immunomodulatory, immunodeficiency, anti-diabetic, anti-viral, anti-bacterial, anti-fungal, anti-hypertensive, anti-atherosclerotic, anti-aging, anti-androgenic, hepatoprotective, radical scavenging properties, neuroprotection, sleep promotion, cholesterol synthesis inhibition, preventing hypoglycemia, inhibition of lipid peroxidation/oxidative DNA damage, maintenance of gut health, prevention of obesity, and stimulation of probiotics (Paterson 2006, De Silva et al. 2012a, b, De Silva et al. 2013, Bishop et al. 2015, Hapuarachchi et al. 2016a, 2016b). The traditional taxonomy of Ganoderma is based on morphological traits, and the genus was divided into two distinct groups, the laccate (G. lucidum complex) and the non–laccate (G. applanatum complex) groups, which correspond to the subgenera Ganoderma and Elfvingia, respectively (Zheng et al. 2007). There are 437 epithets listed in Index Fungorum (2017) for Ganoderma, of which 414 are accepted by Species Fungorum in May, 2017) (http://www.speciesfungorum.org/Names/Names.asp).

“Lingzhi” is the Chinese name mainly referring to G. lucidum (Curtis) P. Karst, which has been widely used in China for medicinal purposes for over two millennia (Sliva 2006). However, this species was originally described from Europe (Ryvarden and Gilbertson 1993). Patouillard (1907) reported G. lucidum from China for the first time and Teng (1934) described collections of G. lucidum from different regions in China. Liu (1974) compiled a monograph of traditional Chinese medicinal fungi, and he reported G. lucidum in his book. Since then, G. lucidum was accepted as the scientific binomial of “Lingzhi” in many reports on Chinese edible and medicinal mushrooms (Ying et al. 1987, Mao 1998, Dai et al. 2009). Moncalvo et al. (1995) mentioned that G. lucidumsensu stricto was distributed in northern and southern Europe, and probably extended to China. However, their further studies confirmed that the species named G. lucidum from both Europe and mainland China was not conspecific based on analyses of ITS and 25S ribosomal DNA sequences. Later, other authors (Pegler and Yao 1996, Smith and Sivasithamparam 2000, Hong and Jung 2004) have confirmed the same idea.

Hawksworth (2005) suggested to conserve the name G. lucidum for an Asian type and introduce a new name for the European species. Later, it was found that G. lucidum from tropical Asia is not conspecific with G. lucidumsensu stricto, and not even conspecific with the real “Lingzhi” distributed in East Asia, and was named G. multipileum Ding Hou, (Wang et al. 2009). Cao et al. (2012) named the medicinal species G. lucidum from China as G. lingzhi. Among the Chinese Ganoderma species, G. flexipes Pat, G. multipileum D. Hou, G. sichuanense J.D. Zhao and X.Q. Zhang, G. tropicum (Jungh.) Bres. and G. tsugae Murrill are the most similar species to G. lingzhi. However, the validity of the separation of G. lingzhi and G. sichuanense has been debated recently. Wang et al. (2012) proposed that ‘G. lucidum’ for Chinese species is incorrect and this should be corrected to Ganoderma sichuanense. Furthermore, Cao et al. (2012) proposed the name G. lingzhi for “Lingzhi” species which has an eastern Asian distribution based on strong morphology and molecular evidence. Yao et al. (2013) proposed G. lingzhi and G. sichuanense as synonyms based on morphological data from an epitype of G. sichuanense. However, Zhou et al. (2015) again challenged this opinion, with G. lingzhi and G. sichuanense being an independent and taxonomically valid species by stressing that species types depends on their ecological environments. Richter et al. (2015) stated that the new taxon G. lingzhi is taxonomically superfluous because the rules of fungal nomenclature require that the oldest valid name of any given taxon should be given preference. In 2016, Mark Stadler annotated this record in Mycobank (http://www.mycobank.org/). Now G. lingzhi is regarded as a later synonym of G. sichuanense in Species Fungorum (http://www.indexfungorum.org/names/names.asp) and Mycobank. Despite all this taxonomic work, the Chinese “Lingzhi” has continuously been referred to as G. lucidum in monographs of Ganodermataceae in China (Hapuarachchi et al. 2015).

The aim of this study is to report and illustrate the new findings of this medicinal species in Thailand and further, to improve the understanding of species delimitation in the genus Ganoderma.

Ganoderma strains used in this study were clustered in six major clades (G. applanatum, G. sichuanense, other laccate and non laccate Ganoderma, G. lucidum species complex, G. orbiforme and Ganoderma species). Sequences obtained from the eight Thai collections clustered in the well-supported G. sichuanense group. The Thai specimens are closely related to the originally described Chinese G. lingzhi taxa (Cui 9166, Cui 6982 and Dai 12426) and the epitype of G. sichuanense (CGMCC5.2175), forming a monophyletic group with G. sichuanense from China with 98% bootstrap support. However, one of the strains of G. sichuanense (Cui7691) of which we retrieved a sequence from GenBank clustered in the G. lucidum species complex. This strain was most likely wrongly identified. The specimens have been collected at some geographical distance (min. 100 m between two collection points), which makes it unlikely that all come from the same mycelium. Nevertheless it is interesting to note that all new isolates cluster together and could not be segregated based on our phylogenetic analyses (Fig. 1). Given the phylogenetic results obtained herein where our new collections are found in a clade with G. sichuanense – including the type specimen – we believe that it would taxonomically more appropriate to establish them as new records of G. sichuanense. Furthermore, the deep nodes are not supported well in the tree, but this does not affect the final conclusions of the study. However, to obtain a better view of the evolution of the genus, a phylogeny with more genes, and in particular single-copy nuclear genes such as tef1 or rpb2 would be recommended.

Ganoderma sichuanense was originally described from the Sichuan Province in 1983 and was diagnosed as having a distinctly radially rugose pileus, with a verrucose or tuberculose upper surface; pore surface yellowish when young, becoming brown or black when bruised; and small spores (Fig. 2) distinguished from other Ganoderma species (Zhao and Zhang 2000). The size range of basidiospores was described as (7.4–9.5 × 5–7) µm cum myxosp., in the original description (Zhao et al. 1983). Later, this range was updated to (7.8–10.4 × 5.2–6.4) µm cum myxosp. (Zhao et al. 1989, Zhao and Zhang 2000) and (9–11.5 × 6.5–8) µm cum myxosp. (Wang et al. 2012). In this study basidiospores were (8.2)8.3–9.8(10.2) × (5.6)5.7–6.8(7.3) µm cum myxosp., which lies within the range given by the original authors and is not distinct from those of basidiospores found in other specimens. Cao et al. (2012) stated that G. sichuanense differs from G. lingzhi in its sessile basidiocarps and smaller basidiospores (7.4–9.2 × 5–6.6) μm (Fig. 3). Furthermore, they revealed that the original description was a mixture of G. sichuanense and G. weberianum especially with the small spores and smooth or slightly echinulate eusporium. Ganoderma curtisii, originally described from North America (Moncalvo and Ryvarden 1997) is a sister taxon to G. sichuanense in the phylogenetic estimate. Ganoderma flexipes, G. multipileum and G. tropicum are also closely related with G. sichuanense and are reported from China.

Figure 2. 

Ganoderma sichuanense (MFU 16-2668). A upper surface B lower surface C cut side of pileus D pore surface E–H spore I generative hyphae J binding hyphae K skeleton hyphae. Scale bars: 10 µm.

Figure 3. 

Microscopic structures of Ganoderma sichuanense (MFU 16-2668) A basidiospores B hyphae from trama C hyphae from context. Scale bars: 5 μm.

Macroscopic, microscopic, and molecular data all confirm that the collections from Thailand belong to G. sichuanense. This is the first discovery of the species in Thailand. The study of more collections of this species is needed to better estimate the variability of this taxon.

This work was financed by the Science Research Foundation of Guizhou University (No. 201309), the featured microbial resources and diversity investigation in Southwest Karst area (2014FY120100), Thailand Research Fund grant – Taxonomy, Phylogeny and biochemistry of Thai Basidiomycetes (BRG 5580009), Research and researcher for industries (RRi) (PhD57I0036), and Higher Education Research Promotion and National Research University Project of Thailand, Office of the Higher Education Commission (2559A30762012).