New Records of the Genus Carcinomyces and Species Carcinomyces polyporina in China

ZHU Xuetai¹*, DU Fan¹, YE Xiaoyan², FAN Jiaxin¹, JIANG Changsheng³
¹College of Life Sciences, Northwest Normal University, Lanzhou 730070, China
²Linxia Hui Autonomous Prefecture Academy of Agricultural Sciences, Linxia 731100, Gansu, China
³Management Bureau of Liancheng National Nature Reserve, Yongdeng 730333, Gansu, China

Abstract

This study reports a macrofungus specimen with distinctive morphology collected from Liancheng National Nature Reserve in Gansu Province. Morphological characterization and molecular phylogenetic analysis based on internal transcribed spacer (ITS) sequences identified the specimen as Carcinomyces polyporina, representing a newly recorded genus and species in China and the first report of this genus in East Asia. Carcinomyces polyporina is characterized by its parasitism on polypore fruiting bodies, forming colloidal mycocecidia, basidia with longitudinal septation, and conidia commonly gemmating from basidiospores. The specimen is deposited in the Herbarium of Cryptogamic Flora, Kunming Institute of Botany, Chinese Academy of Sciences (accession number HKAS 115765).

Keywords: new generic record, new species record, Carcinomyces polyporina, Liancheng National Nature Reserve, systematic classification

Introduction

The genus Carcinomyces (proposed herein) was established by Oberwinkler and Bandoni in 1982 and initially placed within the Heterobasidiomycetes, family Carcinomycetaceae (proposed herein), with its ordinal position undetermined at that time (Oberwinkler & Bandoni, 1982). Species in this genus typically parasitize certain basidiomycete fruiting bodies or plants (Fungsin et al., 2002; Crous et al., 2019), often inducing tumor-like growths in host tissues and forming transparent to translucent gelatinous mycocecidial structures that appear colorless to pale yellow when fresh. The hyphal tips can simultaneously produce conidiophores and basidia.

Carcinomyces polyporina was first described in 1970 and originally placed in the genus Tremella (Reid, 1970). In 1982, Oberwinkler and Bandoni transferred it to Carcinomyces based on its mycocecidial fruiting bodies (Oberwinkler & Bandoni, 1982). However, in 1986, Ginns merged the type species Carcinomyces effibulatus into Syzygospora (Ginns, 1986), sparking controversy over the validity of Carcinomyces and leaving the taxonomic position of C. polyporina unresolved.

Recent molecular phylogenetic studies of the Tremellomycetes have demonstrated that Carcinomyces effibulatus (Ginns, 1978), Carcinomyces arundinariae (Fungsin et al., 2002), and C. polyporina belong to the Basidiomycota, Tremellomycetes, Tremellales, family Carcinomycetaceae, genus Carcinomyces, and are phylogenetically distant from Syzygospora (Liu et al., 2015; Crous et al., 2019). Crous et al. (2019) described Carcinomyces nordestinensis based on molecular and morphological evidence, and their phylogenetic trees supported the recognition of Carcinomyces as a distinct genus within the Tremellales and Carcinomycetaceae. No species of Carcinomyces had previously been reported from China. This study presents morphological and molecular systematic research on a specimen of this genus collected in China.

Materials and Methods

1.1 Specimen Information

The specimen was collected on August 1, 2019, in Pengzigou, Liancheng National Nature Reserve, Yongdeng County, Lanzhou City, Gansu Province, within a mixed coniferous-broadleaf forest at an elevation of 1,941 m (coordinates: 102°44′55.257″E, 36°37′42.288″N). The dominant vegetation included Picea crassifolia, Picea wilsonii, and Betula albosinensis. The field collection number was ye629, and the herbarium accession number is HKAS 115765.

1.2 Morphological Observation

Ecological photographs were taken using a Panasonic Lux 10 camera. Dry specimens were examined for color and shape using a Motic SMZ-171 dissecting microscope. Hand sections were prepared and mounted in 5% KOH solution for microscopic examination with a Zeiss AX10 light microscope; micrographs were captured with a Canon 70D camera. Twenty mature conidia and basidiospores were measured, with dimensions expressed as (a)b–c(d), where a and d represent the minimum and maximum values, and b–c represent the 90% confidence interval. The length-to-width ratio (Q) was calculated, with Qm representing the mean Q value ± standard deviation (Wu et al., 2016).

1.3 Molecular Phylogenetic Analysis

Total DNA was extracted using the CTAB method. The internal transcribed spacer (ITS) region was amplified using primers ITS5 (5′-GGAAGGTA AAAGTCAAGG-3′) and ITS4 (5′-TCCTCCGCTTATTGATATGC-3′) (White et al., 1990). PCR products were sequenced by Beijing Aoke Dingsheng Biotechnology Co., Ltd. The resulting sequences were manually edited and adjusted using BioEdit (Hall, 1999), subjected to BLAST analysis in NCBI, and submitted to GenBank.

Based on Liu et al. (2015), relevant ITS sequences were retrieved from GenBank and combined with our newly obtained sequence to construct a dataset. Maximum likelihood (ML) phylogenetic analysis was performed using RAxML 8.1.24 with the GTRGAMMAI nucleotide substitution model and default parameters (Stamatakis, 2014). Neighbor-joining (NJ) analysis was conducted using MEGA 7.0.26. Bootstrap support was assessed with 1,000 replicates for both methods. Sequence information, including species names, origins, and GenBank accession numbers, is provided in Table 1.

Table 1 Information on ITS sequences used for phylogenetic tree construction

Note: Bold indicates newly submitted sequences from this study.

Results

Phylogenetic trees constructed using ML and NJ methods based on ITS sequences showed essentially identical topologies with only slight differences in support values. The ML tree is presented in Figure 1, with bootstrap percentages from ML (BP1) and NJ (BP2) analyses shown on branches. Our sequence clustered with the Spanish C. polyporina specimen AM20 with high support (BP1 = 100, BP2 = 100) and formed a well-supported clade (BP1 = 99, BP2 = 98) with other Carcinomyces species including the type species C. effibulatus.

Morphological examination of specimen HKAS 115765 revealed the following characteristics. The fungus parasitizes the hymenium of polypores (Figure 2), forming translucent to transparent gelatinous mycocecidia that appear slightly milky when fresh and dry into thin, membranous, brown to dark brown films. Conidiophores and conidia are common; conidiophores are short and club-shaped. Conidia are long-elliptical to fusiform, smooth, thin-walled, measuring (3.5)4.4–5.4(8.0) × (1.5)2.5–3.0(4.5) μm with Qm = 1.80 ± 0.12. Basidia are subglobose, 9.8–12.8 × 8.8–11.0 μm, with longitudinal septation; sterigmata are 2- or 4-celled, up to 8 μm long. Basidiospores are globose to subglobose, (4.8)5.0–5.5(6.0) × (4.5)4.6–4.8(5.1) μm with Qm = 1.10 ± 0.01, and commonly germinate to produce conidia (Figure 3). Clamp connections are present.

Based on the combined morphological and molecular evidence, we confirm that this specimen represents Carcinomyces polyporina (D.A. Reid) A.M. Yurkov, 2015 ≡ Tremella polyporina D.A. Reid, Trans. Br. Mycol. Soc. 1970.

Distribution: United Kingdom (Reid, 1970; Roberts, 2007), North America (Setliff, 1982), Spain (Millanes et al., 2011), Poland (Karasiński & Wołkowycki, 2015), China.

Figure 1. Molecular phylogenetic tree based on ITS dataset using maximum likelihood. Bootstrap percentages (BP) from ML and NJ analyses (1,000 replicates) are shown left and right on major branches, respectively.

Figure 2. Macroscopic morphology of Carcinomyces polyporina and its host. A. Dorsal view of host; B. Ventral view of host; C. Host hymenium with gelatinous mycocecidia of C. polyporina. a. Gelatinous mycocecidium of C. polyporina. Bars: A, B = 5 mm, C = 2 mm.

Figure 3. Microscopic structures of Carcinomyces polyporina and its host. A. Probasidium of C. polyporina; B. Mature basidium with longitudinal septation of C. polyporina; C. Basidiospore germination of C. polyporina; D. Conidiophore of C. polyporina; E. Elliptical conidia of C. polyporina; F. Subglobose basidiospores of C. polyporina; G. Botuliform basidiospores of host. Bars = 5 μm.

Discussion

This study confirms specimen HKAS 115765 collected from Liancheng National Nature Reserve, Gansu Province, as Carcinomyces polyporina, representing a new generic and specific record for China. The genus name Carcinomyces derives from the Greek karkinos (cancer, tumor), and we propose the Chinese name "胶瘤菌" (jiāo liú jūn, gelatinous tumor fungus) based on its gelatinous fruiting bodies. The specific epithet polyporina indicates its common parasitism on polypore hymenia, leading us to propose "孔生胶瘤菌" (kǒng shēng jiāo liú jūn, pore-born gelatinous tumor fungus) as the Chinese species name. Wang et al. (2010) mentioned the family Carcinomycetaceae in their report of Syzygospora mycetophila in China but did not provide a Chinese name; we propose "胶瘤菌科" (jiāo liú jūn kē, gelatinous tumor fungus family) based on its etymology.

Regarding systematic classification, the type species Carcinomyces effibulatus was previously transferred to Syzygospora by some researchers (Ginns, 1986). Syzygospora is currently placed in the Filobasidiales, Filobasidiaceae (Millanes et al., 2011; Liu et al., 2015), and Index Fungorum follows this classification, placing Carcinomyces in Filobasidiales, Filobasidiaceae (http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=823057). However, the phylogenetic tree of Tremellomycetes constructed by Liu et al. (2015) shows that C. effibulatus, C. arundinariae, and C. polyporina form a highly supported monophyletic clade constituting a monotypic family—Carcinomycetaceae—within the Tremellales. In contrast, the type species of Syzygospora, S. alba, is positioned within the Filobasidiales, Filobasidiaceae, phylogenetically distant from Carcinomyces. Morphologically, Carcinomyces species predominantly parasitize basidiomycete fruiting bodies, forming mycocecidia with subglobose to cylindrical basidia that develop longitudinal or cruciate septa upon maturity. In contrast, Filobasidiaceae species mostly parasitize lichens and possess tubular or long-clavate basidia without septation. Therefore, both molecular and morphological evidence support the placement of Carcinomyces in the Tremellales, Carcinomycetaceae, rather than in the Filobasidiales, Filobasidiaceae, necessitating a taxonomic revision in the Index Fungorum database.

The genus Carcinomyces currently comprises only four recognized species: C. effibulatus (type species) (Ginns, 1978), C. arundinariae (Fungsin et al., 2002), C. nordestinensis (Crous et al., 2019), and C. polyporina (Reid, 1970). These parasitic fungi exhibit complex and unique host relationships. For example, C. effibulatus is known only from Collybia dryophila fruiting bodies (Ginns, 1986); C. nordestinensis parasitizes leaves of Bromelia antiacantha while also occurring as an endophyte in Handroanthus impetiginosus (Crous et al., 2019); and C. polyporina has been recorded on Tyromyces lacteus and Antrodia sinuosa (Reid, 1970; Roberts, 2007). We were unable to obtain host DNA from our specimen, but based on morphological characteristics such as blue bruising of the fruiting body and botuliform basidiospores, we hypothesize the host belongs to Tyromyces or a related genus, though definitive identification requires additional specimens and study.

Previous records of C. polyporina were limited to Europe and North America (Reid, 1970; Setliff, 1982; Roberts, 2007; Millanes et al., 2011). Its discovery in China represents the first report from East Asia. As fungal diversity research continues to expand in scope and depth, additional Carcinomyces species will likely be discovered in more locations, clarifying their distribution patterns and ecological characteristics.

References

WHITE TJ, BRUNS T, LEE S, et al., 1990. PCR protocols: a guide to methods and applications. Amplification and direct sequencing of fungal ribosomal RNA genes for phylogenetics[M]. San Diego: Academic Press: 315-322.

CROUS PW, CARNEGIE AJ, WINGFIELD MJ, et al., 2019. Fungal Planet description sheets: 868–950[J]. Persoonia, 42: 291-473.

FUNGSIN B, TAKASHIMA M, ARTJARIYASRIPONG S, et al., 2002. Bullera arundinariae sp. nov., a new species of ballistoconidium-forming yeast isolated from a plant in Thailand[J]. Microbiol Cult Collect, 18: 25-34.

GINNS J, SUNHEDE S, 1978. Three species of Christiunsenia (Corticiaceae) and the teratological galls on Collybia dryophila[J]. Bot Notiser, 131: 167-173.

GINNS J, 1986. The genus Syzygospora (Heterobasidiomycetes: Syzygosporaceae)[J]. Mycologia, 78(4): 619-621.

HALL TA, 1999. BioEdit: a user‐friendly biological sequence alignment editor and analysis program for Windows 95/98/NT[J]. Nucl Acids Symp Ser, 41: 95‐98.

KARASIŃSKI D, WOŁKOWYCKI M, 2015. An annotated and illustrated catalogue of polypores (Agaricomycetes) of the białowieża forest (NE Poland)[J]. Pol Bot J, 60(2): 217-292.

LIU XZ, WANG QM, GÖKER M, et al., 2015. Towards an integrated phylogenetic classification of the Tremellomycetes[J]. Stud Mycol, 81: 85-147.

MILLANES AM, DIEDERICH P, EKMAN S, et al., 2011. Phylogeny and character evolution in the jelly fungi (Tremellomycetes, Basidiomycota, Fungi)[J]. Mol Phylogenet Evol, 61(1): 12-28.

OBERWINKLER F, BANDONI R, 1982. Carcinomycetaceae: a new family in the Heterobasidiomycetes[J]. Nord J Bot, 2(5): 501-516.

REID DA, 1970. New or interesting records of British Hymenomycetes, IV[J]. Trans Brit Mycol Soc, 55(3): 413-416.

ROBERTS P, 2007. British Tremella species IV: Tremella obscura, T. penetrans, T. giraffa & T. polyporina[J]. Field Mycol, 8(4): 127-133.

SETLIFF EC, 1982. Tremella polyporina from New York State[J]. Can J Bot, 60(6): 1028-1029.

STAMATAKIS A, 2014. RAxML version 8: a tool for phylogenetic analysis and post-analysis of large phylogenies[J]. Bioinformatics, 30(9): 1312-1313.

WANG Y, FAN YG, TULIGUER, 2010. Checklist of macrofungi collected from different forests in Changbai Mountain (Ⅲ): Coniferous forest[J]. J Fungal Res, 8(4): 200-210.

WU G, LI YC, ZHU XT, et al., 2016. One hundred noteworthy boletes from China[J]. Fungal Divers, 81(1): 1-227.