Four new fungi from Xizang in southwest China, Calocera ramaria, Ceraceomyces rhizomorphus, Leptosporomyces linzhiensis, and Ramaria xizangensis are described and illustrated based on the morphological and molecular evidence. Calocera ramaria is characterized by the ramal and bright orange basidiomata, a monomitic hyphal system with simple septa generative hyphae, usually 4-septate basidiospores; Ceraceomyces rhizomorphus is characterized by the cream to yellowish basidiomata with rhizomorphs, cylindrical basidiospores; Leptosporomyces linzhiensis is characterized by white with pink basidiomata, cylindrical to oblong ellipsoid basidiospores; Ramaria xizangensis is characterized by flesh pink basidiomata, branched dichotomously in 4–5 ranks, a monomitic hyphal system with clamped generative hyphae, ellipsoid to cylindrical and densely warted basidiospores.

Molecular systematic, phylogenetic analysis, taxonomy, wood-decaying fungi

The fruiting bodies of Basidiomycota exhibit complex forms, such as gilled, poroid, toothed, coralloid basidiomata. Numerous taxonomists have endeavored to construct a stable classification system based on these characters (Gäumann 1953). Recently, the analysis of DNA sequences has emerged as a common method for deducing fungal phylogenies and enhancing higher classification frameworks through the integration of genetic traits (Cui et al. 2019; Wijayawardene et al. 2020; Liu et al. 2023).

The abundance of biodiversity in Abies forests can be attributed to the plentiful presence of humus and mycorrhizal fungi, which foster an optimal environment for the proliferation of the macrofungal species. Information regarding the fungal diversity in Abies communities is scattered over a range of publications (Ryvarden and Gilbertson 1993; Dai 2022). Ceraceomyces Jülich, a small genus characterized by yellow rhizomorphic basidiomata, was established by Jülich based on the taxon C. tessulatus (Cooke) Jülich (Jülich 1972). This genus, originally from North America, features annual, resupinate, pellicular basidiomata with a smooth or merulioid hymenial surface, a monomitic hyphal system, narrowly clavate basidia, and subglobose, narrowly ovate, ellipsoid to cylindrical basidiospores (Chikowski et al. 2016). Phylogenetic studies revealed that Ceraceomyces was polyphyletic, comprising three distinct groups. The section of Corticium tessulatum Cooke belonged to Polyporales, and Ceraceomyces serpens (Tode) Ginns and C. eludens K.H. Larss. were part of phlebioid clade (Larsson et al. 2004). A recent study indicated that the type species, Corticium tessulatum is classified under the order Amylocorticiales (Binder et al. 2010; Chikowski et al. 2016), as well as species, C. yunnanensis Qi Yuan & C.L. Zhao and C. borealis (Romell) J. Erikss. & Ryvarden (Yuan et al. 2023). Currently, eleven species are recognized in the genus Ceraceomyces, including C. cystidiatus (J. Erikss. & Hjortstam) Hjortstam, C. eludens, C. microsporus K.H. Larss. and C. sublaevis (Bres.) Jülich were accepted in the genus. A genus, Crystallicutis El-Gharabawy, Leal-Dutra & G.W. Griff. was derived from Ceraceomyces based on the crystals in the hymenium and subiculum of the basidiomata, which includes the brown-rot species C. serpens (El-Gharabawy et al. 2021). Both species C. sulphurinus and C. violascens (Fr.) Jscens were recorded in Ceraceomyces, are considered congeneric with Rhizochaete Gresl., Nakasone & Rajchenb. due to the characteristics like the rhizomorphic margin and the purple reaction in KOH.

Calocera (Fr.) Fr. is known for its distinctive characteristics, stipitate, fasciculate or scattered, gelatinous basidiomata, dendroid or staghorn-like, subclavate to clavate basidia and probasidia, as well as cylindrical to reniform, septate or non-septate basidiospores (Fisher 1931; Lowy 1971; Peng et al. 1992; Wu et al. 2011; Shirouzu et al. 2017). Recent phylogenetic analyses of the class Dacrymycetes demonstrated that Calocera was polyphyletic and species in the genus are scattered throughout the family Dacrymycetaceae together with most of the species of Dacrymyces Nees (1817: 89) as well as a few species from other genera such as Dacryopinax G.W. Martin (1948: 116) and Femsjonia Fr. (Shirouzu et al. 2007; Zamora and Ekman 2020).

The genus Leptosporomyces Jülich is characterized by the resupinate basidiomata, white yellow and smooth hymenial surface, a monomitic hyphal system with clamped connections, and thin-wall, smooth, acyanophilous basidiospores. Recent research has indicated that Leptosporomyces was polyphyletic, with two taxa, L. galzinii (Bourdot) Jülich and L. raunkiaeri (M.P. Christ.) Jülich, grouped in the order Atheliales, while L. septentrionalis (J. Erikss.) Krieglst. was placed in the order Amylocorticiales (Larsson 2007; Hodkinson et al. 2014; Sulistyo et al. 2021). The generic delimitation of Fibulomyces Jülich and Leptosporomyces remains controversial, with both being indistinguishable in phylogenetic and morphological analyses, leading to the former being considered as a synonym of the latter (Bernicchia and Gorjón 2010).

Ramaria Fr. ex Bonord. is a widely distributed non-gilled Basidiomycete genus (Marr and Stuntz 1973; Petersen 1981; Humpert et al. 2001). The genus is recognized by branched basidiomata, mono- to dimitic hyphal systems with clamped or simple-septate generative hyphae, and smooth to echinulate, verrucose-reticulate or striate ornamentation basidiospores (Corner 1950; Marr and Stuntz 1973; Petersen 1981; Humpert et al. 2001). The genus has been classified into four subgenera, namely R. subg. Ramaria, R. subg. Laeticolora Marr & D.E. Stuntz, R. subg. Lentoramaria Corner, and R. subg. Echinoramaria Corner (Marr and Stuntz 1973; Humpert et al. 2001; Exeter et al. 2006; Knudson 2012; Hanif et al. 2019). Initially, Ramaria was treated as a subgenus within Clavaria (Coker 1923; Doty 1944) until Corner (1970) elevated it to genus rank. Studies based on the morphological and molecular data agree on the paraphyletic state of Ramaria (Humpert et al. 2001; Hosaka et al. 2006; Giachini et al. 2010).

In the present paper, species from four genera are collected from Xizang under forest of Abies, and the phylogenetic relationships of four taxa are still unclear. Thus, to explore the diversity and taxonomic status with different characters for those taxa will be significant for macrofungi in Xizang, and the taxonomy and phylogeny analysis show that they are new to science.

The specimens were collected from Xizang which were deposited in the herbarium of the Southwest Forestry University (SWFC), Kunming, Yunnan Province, China. Samples were photographed when fresh in the field, and their habitats were recorded. Microscopic structures were discussed by Zhao et al. (2023). Special color terms were set by Anonymous (1969) and Petersen (1996). A Nikon Digital Sight DS-L3 or Leica ICC50 HD camera (magnification ×1,000) was used to exam hand-cut sections of basidiomata, which were first treated with 5% KOH for a few minutes and then with 1% phloxine B (C₂₀H₄Br₄Cl₂K₂O₅). At least 30 basidiospores of each species were examined. The values were expressed as a mean with 5% of the measurements excluded from each end of the range, given in parentheses. Stalks were excluded for basidia measurement, and the hilar appendages were excluded for basidiospore measurement.

Wood decay fungi encompasses the vast group of aphyllophoroid fungi with corticioid, prioid or jelly form of basidiomata (Herter 1910). This classification has historically been used to define the different families of Basidiomycetes. However, molecular studies have revealed that many of these fungi are distributed across various orders within the Basidiomycetes, including the likes of Amylocorticiales, Atheliales, Dacrymycetales, and Gomphales (Kirk et al. 2018; Wei et al. 2022). As a result, further research is needed to elucidate the relationships and morphological variability of these taxa through phylogenetic analysis.

The Xizang Autonomous Region, situated in the southwest of China, is renowned as one of the most bio-diverse regions in the country. This is attributed to its complex topography and diverse ecosystems, making it a focal point for fungal biodiversity in China. Recently, studies focusing on fungal diversity and the ecology of Basidiomycota in Xizang were carried out (Ke 2016; Pubu et al. 2016; Wang et al. 2023). According to the study (Pubu et al. 2016), 1733 species were collected in Xizang. The fungal research indicated that Sejila Mountain National Forest Park is predominantly composed of spruce and fir trees, which provide an ideal habitat for a rich diversity of macrofungi species to flourish (Zhao and Li 1987). In our study, four species were found from Xizang, Calocera ramaria, Ceraceomyces rhizomorphus, Leptosporomyces linzhiensis, and Ramaria xizangensis.

Calocera is characterized by its yellow, gelatinous basidiomata, resembling Dacrymyces. However, Dacrymyces displays a broader range of basidiomata forms, including pulvinate, discoid, turbinate, spathulate, flabellate, and cylindrical shapes (Shirouzu et al. 2009; Fan et al. 2021), whereas Calocera exhibits branched, dendroid basidiomata. Our results have further confirmed that our newly discovered species features ramal basidiomata and clusters phylogenetically with Calocera species, placing it within the genus Calocera. In Xizang, two species have been identified, C. ramaria and C. tibetica, but the latter has wider basidiospores (5–6 µm vs. 3.9–4.4 µm, Fan et al. 2021). In our phylogenies, C. viscosa and C. cornea were related to C. ramaria (Fig. 1); however, C. viscosa has 1-septate mature basidiospores, and C. cornea differs from C. ramaria by its distinctly larger basidiospores (7–10 × 3–4.5 μm vs. 9.2–11 × 3.9–4.4 μm) with one septum (McNabb 1965; Shirouzu et al. 2009).

Previous research has highlighted the polyphyly of Ceraceomyces (Chikowski 2016; Yuan et al. 2023), and seven species are retained in Ceraceomyces. However, it is worth noting that authentic specimens and DNA data are lacking for Ceraceomyces species. Phylogenetically, C. rhizomorphus formed a sister group with C. yunnanensis and C. borealis, but C. yunnanensis has smaller basidiospores (3–4 × 1–1.5 µm vs. 4.7–6.2 × 1.8–2.3 µm, Yuan et al. 2023) and C. borealis has larger basidiospores (6–8 × 1.8–2 µm vs. 4.7–6.2 × 1.8–2.3 µm, Bernicchia and Gorjón 2010).

Ceraceomyces rhizomorphus and C. tessulatus had similar yellowish basidiomata with rhizomorphs when fresh, while C. tessulatus has ellipsoid and larger basidiospores (6–8 × 3.5–4.5 µm vs. 4.7–6.2 × 1.8–2.3 µm, Bernicchia and Gorjón 2010). Three known species, C. bizonatus, C. reidii, and C. simulans also distributed in Asia. However, C. bizonatus has shorter basidiospores (2.5–3.3 µm vs. 4.7–6.2 µm, Bernicchia and Gorjón 2010); C. reidii has larger basidiospores (11.5–15 × 4.5–6 µm vs. 4.7–6.2 × 1.8–2.3 µm, Bernicchia and Gorjón 2010); C. simulans has longer basidiospores (6–7 µm vs. 4.7–6.2 µm, Bernicchia and Gorjón 2010).

Leptosporomyces linzhiensis is similar to L. thindii in having white basidiomata and being distributed in Asia, but the latter has wider basidiospores (Prasher 2015). Leptosporomyces linzhiensis sisters to L. septentrionalis by its white basidiomata, and cylindrical basidiospores, but the latter has slightly shorter basidiospores (3–4 μm vs. 3.8–4.3 μm), and 2–4 basidia (Prasher 2015). Leptosporomyces linzhiensis is easily confused with L. roseus in, but the latter has shorter basidiospores (2–2.5 μm vs. 3.8–4.3 μm, Prasher 2015). Leptosporomyces fuscostratus has a broad distributional range in the northern hemisphere, but it has wider basidiospores (2–2.8 μm vs. 1.7–2 μm, Yurchenko and Wołkowycki 2022).

In our phylogeny, Ramaria is paraphyletic, which included four clades, R. sub. Laeticolora and R. sub. Lentoramaria, R. sub. Ramaria and R. sub. Echinormaria. Ramaria xizangensis was clustered in Ramaria sub. Laeticolora with Ramaria amyloidea, R. celerivirescens and R. claviramulata. However, R. celerivirescens has slightly wider basidiospores (4–6 µm vs. 3.9–4.9 µm, Marr and Stuntz 1973). R. claviramulata has cream to brownish white basidiomata. Ramaria xizangensis is similar to R. indoyunnaniana in having pink basidiomata and being distributed in Yunnan, but the latter has shorter basidiospores (7.2–8.3 µm vs. 9.7–11.8 µm, Petersen and Zang 1986).

According to our field inventory, the four Chinese new species were found in alpine zone near the Sejila Mountain, and the coniferous forest dominant by Abies at high altitude with cold and humid environments. Previously, numerous new species have been found in Southwest China (Dai 2022; Zhao et al. 2023), and the present paper confirms the fungal diversity is very rich in the montane forests of Southeast Xizang.