Culturable mycobiota from Karst caves in China, with descriptions of 20 new species

Abstract

Karst caves are distinctly characterised by darkness, low to moderate temperatures, high humidity, and scarcity of organic matter. During the years of 2014-2015, we explored the mycobiota in two unnamed Karst caves in Guizhou province, China, and obtained 563 fungal strains via the dilution plate method. Preliminary ITS analyses of these strains suggested that they belonged to 246 species in 116 genera, while 23.5 % were not identified to species level. Among these species, 85.8 % (211 species) belonged to Ascomycota; 7.3 % (18 species) belonged to Basidiomycota; 6.9 % (17 species) belonged to Mucoromycotina. The majority of these species have been previously known from other environments, mostly from plants or animals as pathogens, endophytes or via a mycorrhizal association. We also found that 59 % of these species were discovered for the first time from Karst caves, including 20 new species that are described in this paper. The phylogenetic tree based on LSU sequences revealed 20 new species were distributed in six different orders. In addition, ITS or multi-locus sequences were employed to infer the phylogenetic relationships of new taxa with closely related allies. We conclude that Karst caves encompass a high fungal diversity, including a number of previously unknown species. Novel species described include: Amphichorda guana, Auxarthronopsis guizhouensis, Biscogniauxia petrensis, Cladorrhinum globisporum, Collariella quadrum, Gymnoascus exasperatus, Humicola limonisporum, Metapochonia variabilis, Microascus anfractus, Microascus globulosus, Microdochium chrysanthemoides, Paracremonium variiforme, Pectinotrichum chinense, Phaeosphaeria fusispora, Ramophialophora globispora, Ramophialophora petraea, Scopulariopsis crassa, Simplicillium calcicola, Volutella aeria, and Wardomycopsis longicatenata.

Keywords: ITS DNA barcodes; diversity; morphology; systematics; troglobitic fungi.

Fig. 1

Visited caves. a. Entrance to Cave 1; b. stalactite; c. pool at the end of Cave 1; d. sampled rocks; e. soil sediment; f. pellucid tadpole; g. bat guano colonised by fungal mycelia; h–i. faeces from unknown animals.

Fig. 2

Maximum likelihood (ML) tree based on LSU sequences showing the order placements of new species described in this study. ML bootstrap values (≥ 70 %) and Bayesian posterior probability (≥ 75 %) are indicated along branches (ML/PP). The tree is rooted with Sarcoscypha coccinea (FF176859). Novel species are indicated in bold font and the orders are shown on the right side of the figure.

Fig. 3

Amphichorda guana (from ex-holotype CGMCC 3.17908). a. A. guana on bat guano; b–c. upper and reverse views of cultures on PDA and SNA 10 d after inoculation; d. synnemata; e–f. conidiophores and conidia; g. conidia. — Scale bars: e–g = 10 μm.

Fig. 4

Auxarthronopsis guizhouensis (from ex-holotype CGMCC 3.17910). a–b. Upper and reverse views of cultures on PDA and SNA 21 d after inoculation; c–g. arthroconidia and aleurioconidia (d–g. arthroconidia and aleurioconidia in cotton blue). — Scale bars: c–g = 10 μm.

Fig. 5

Biscogniauxia petrensis (from ex-holotype CGMCC 3.17912). a–b. Upper and reverse views of cultures on PDA and SNA 14 d after inoculation; c. exudate; d. conidiomata under stereomicroscope; e–g. conidiophores and conidia; h. conidia. — Scale bars: e–h = 10 μm.

Fig. 6

Cladorrhinum globisporum (from ex-holotype CGMCC 3.17921). a–b. Upper and reverse views of cultures on PDA and SNA 21 d after inoculation; c. sporodochium on SNA; d–h. phialides; i. conidia; j. coiled mycelia. — Scale bars: d–j = 10 μm.

Fig. 7

Collariella quadrum (from ex-holotype CGMCC 3.17917). a–b. Upper and reverse views of cultures on PDA and SNA 18 d after inoculation; c, e. ascomata; d. masses of ascospores; f–g. outer surface of peridium; h–i. ascomatal hairs; j–k. asci; l. ascospores. — Scale bars: c, e = 100 μm; h = 50 μm; f–g, i–l = 10 μm.

Fig. 8

Gymnoascus exasperatus (from ex-holotype CGMCC 3.17923). a–b. Upper and reverse views of cultures on PDA and SNA 21 d after inoculation; c. fertile mycelial structure; d, f. terminal, lateral and intercalary conidia; e. racquet hyphae; g. conidia. — Scale bars: d = 20 μm; e–g = 10 μm.

Fig. 9

Humicola limonisporum (from ex-holotype CGMCC 3.17914). a–b. Upper and reverse views of cultures on PDA and SNA 20 d after inoculation; c. ascomata; d. outer surface of peridium; e. ascomatal hairs; f–g. asci; h. ascospores; i. aleurioconidia. — Scale bars: c = 100 μm; f = 50 μm; d–e, g–i = 10 μm.

Fig. 10

Metapochonia variabilis (from ex-holotype CGMCC 3.17925). a–b. Upper and reverse views of cultures on PDA (10 d) and SNA (21 d); c, e. phialides; d. conidia aggregated in slimy head; f. conidia. — Scale bars: c–f = 10 μm.

Fig. 11

Microascus anfractus (from ex-holotype CGMCC 3.17950). a–b. Upper and reverse views of cultures on PDA and SNA 21 d after inoculation; c, e. coiled mycelia; d–f. conidiogenous cells and conidia; g. conidia; h–i. swollen mycelia. — Scale bars: c–h = 10 μm; i = 20 μm.

Fig. 12

Microascus globulosus (from ex-holotype CGMCC 3.17927). a–b. Upper and reverse views of cultures on PDA (21 d) and SNA (42 d); c–f. conidiogenous cells and conidia in cotton blue; g–h. conidia. — Scale bars: c–h = 10 μm.

Fig. 13

Microdochium chrysanthemoides (from ex-holotype CGMCC 3.17929). a–b. Upper and reverse views of cultures on PDA (10 d) and SNA (14 d); c. sporodochia semi-submerged in agar (black arrow); d–e. sporodochia; f–g. conidiogenous cells from sporodochia; h–i. conidia forming on conidiophore directly (stained with cotton blue); j–k. conidia. — Scale bars: d–k = 10 μm.

Fig. 14

Paracremonium variiforme (from ex-holotype CGMCC 3.17931). a–b. Upper and reverse views of cultures on PDA and SNA 21 d after inoculation; c. sporulation on PDA under stereomicroscope; d–e. conidiophores, phialides and conidia; f. phialides and conidia in cotton blue; g. conidia. — Scale bars: d–e = 20 μm; f–g = 10 μm.

Fig. 15

Pectinotrichum chinense (from ex-holotype CGMCC 3.17935). a–b. Upper and reverse views of cultures on PDA and SNA 20 d after inoculation; c. aerial mycelia; d–e. conidiophores and conidiogenous cells; f. conidia. — Scale bars: d–f = 10 μm.

Fig. 16

Phaeosphaeria fusispora (from ex-holotype CGMCC 3.17937). a–b. Upper and reverse views of cultures on PDA and SNA 28 d after inoculation; c. exudates; d. section of ascomata; e–i. asci and ascospores. — Scale bars: d, f = 50 μm; e, g = 20 μm; h–i = 10 μm.

Fig. 17

Ramophialophora globispora (from ex-holotype CGMCC 3.17939). a–b. Upper and reverse views of cultures on PDA and SNA 21 d after inoculation; c. conidial beam on SNA under stereomicroscope; d. conidial beam; e–f. rough-walled conidiophores; g. conidia. — Scale bars: d = 20 μm; e–g = 10 μm.

Fig. 18

Ramophialophora petraea (from ex-holotype CGMCC 3.17952). a–b. Upper and reverse views of cultures on PDA and SNA 21 d after inoculation; c–f. phialides and conidia; g. conidia. — Scale bars: c–g = 10 μm.

Fig. 19

Scopulariopsis crassa (from ex-holotype CGMCC 3.17941). a–b. Upper and reverse views of cultures on PDA and SNA 21 d after inoculation; c. conidiomata; d–e. conidiophores; f–g. conidia. — Scale bars: d–g = 10 μm.

Fig. 20

Simplicillium calcicola (from ex-holotype CGMCC 3.17943). a–b. Upper and reverse views of cultures on PDA (10 d) and SNA (21 d); c. phialides on synnemata; d–f. phialides; g–h. microconidia and macroconidia. — Scale bars: c–h = 10 μm.

Fig. 21

Volutella aeria (from ex-holotype CGMCC 3.17945). a–b. Upper and reverse views of cultures on PDA and SNA 14 d after inoculation; c–d. sporodochia under stereomicroscope and microscope; e–f. conidiophores and phialides from sporodochia; g. conidia from sporodochia; h–i. conidiophores and phialides from aerial mycelia; j. conidia from aerial mycelia. — Scale bars: d = 100 μm; e–g, j = 10 μm; h = 50 μm; i = 20 μm.

Fig. 22

Wardomycopsis longicatenata (from ex-holotype CGMCC 3.17947). a–b. Upper and reverse views of cultures on PDA and SNA 8 wk after inoculation; c. immersed ascoma; d. ascoma; e. peridium; f. asci; g. ascospore; h–k. conidiophores and conidiogenous cells; l–m. conidia. — Scale bars: d = 100 μm; e, l = 20 μm; f–k, m = 10 μm.