Trichoderma cavernicola X.F. Liu, Karun. & Tibpromma, 2025

Liu, Xiangfu, Tibpromma, Saowaluck, Gautam, Ajay K., Suwannarach, Nakarin, Elgorban, Abdallah M., Chukeatirote, Ekachai, Thilini Chethana, K. W. & Karunarathna, Samantha C., 2025, A novel species and a new host record of Trichoderma from caves in Yunnan Province, China, Phytotaxa 694 (2), pp. 119-143 : 134

Trichoderma cavernicola X.F. Liu, Karun. & Tibpromma , sp. nov. Fig. 3

Index Fungorum Number: IF 903158; Facesoffungi Number: FOF 17066.

Holotype: GMB-W1117

Etymology: “Caverna” means cave, and “cola” means dweller or inhabitant in Latin; thus, “cavernicola ” refers to the cave habitat of the holotype.

Fungus associated with bat guano in caves. Asexual morph on PDA: Vegetative hyphae 2–8 μm wide, septate, branched, hyaline, smooth-walled. Conidiophores pyramidal with verticillate, comprising a recognizable main axis, branches pairs or solitary, paired lateral branches, longer branches near the base, and short branches or solitary phialides arising near the tip. Phialides 5–16 × 2–9 µm (x̄ = 10.88 × 5.46 μm, n = 80), ampulliform to lageniform, generally formed on terminal branches in divergent whorls of 2–4(–5). Supporting cells 4–22 × 2–8 µm (x̄ = 11.09 × 4.94 μm, n = 90). Conidia 4–7 × 2–5 µm (x̄ = 5.12 × 4.34 μm, n = 100), ellipsoidal to ovoid, straight to slightly curved, light grey to green, smooth-walled. Chlamydospores 4–12 × 3–10 µm (x̄ = 8.36 × 6.43 μm, n = 70), single or in clusters, terminal and intercalary, variable in shape, mostly subglobose to globous, thick-walled, hyaline, granulate. Sexual morph: Undetermined.

Culture characteristics: Colonies on PDA attaining 60 mm after 10 days at room temperature (20–25 ℃), white, pale yellow to green, sparse aerial mycelium on the surface; reverse white to pale yellow. The white reproductive mycelium covers the stromatic colonies after 25 days. Odor absent.

Material examined: China, Yunnan Province, Nujiang Lisu Autonomous Prefecture, Lushui City, Daxingdi Town, Walaya cave, bat guano, N 26.080743, E 98.848391, elev. 850.46 m, 23 April 2024, Xiangfu Liu and Xuemei Chen, NJ-12 A (Holotype, GMB-W 1117), ex-type GMBCC 1103, other living culture GMBCC 1105.

Notes: In our phylogenetic analyses of ITS, RPB 2, and TEF 1-α, Trichoderma cavernicola formed a distinct lineage with 99% ML and 1.00 PP support, clustering sister to T. neoguizhouense C.L. Zhang , T. densissimum C.L. Zhang , T. paradensissimum C.L. Zhang , and T. afroharzianum P. Chaverri, F.B. Rocha, Degenkolb & Druzhin. in the Harzianum clade ( Fig. 1 ). However, the nucleotide comparisons between Trichoderma cavernicola ( GMBCC 1103, type) and T. neoguizhouense ( GDMCC 3.1012, type) showed that there are 4.89% (44/900 bp, without gap) base pair differences in RPB 2 and 2.03% (16/790 bp, 6 gaps) differences in TEF 1-α, and T. neoguizhouense lacks the ITS sequence. Trichoderma cavernicola ( GMBCC 1103, type) and T. densissimum ( CGMCC 3.24126, type) showed that there are 3.43% (26/757 bp, without gap) differences in RPB 2 and 1.52% (12/790 bp, 3 gaps) differences in TEF 1-α, and the ITS sequence is lacking for T. densissimum . Trichoderma cavernicola ( GMBCC 1103, type) and T. paradensissimum ( CGMCC 3.24125, type) showed that there are 3.43% (26/757 bp, without gap) differences in RPB 2 and 1.52% (12/790 bp, 4 gaps) differences in TEF 1-α, and T. paradensissimum lacks ITS sequence. Trichoderma cavernicola ( GMBCC 1103, type) and T. afroharzianum ( CBS 124620, type) showed that there are 2.55% (15/589 bp, 3 gaps) differences in ITS, 4.07% (34/836 bp, without gap) differences in RPB 2, and 7.02% (25/484 bp, 9 gaps) differences in TEF 1-α.

Morphologically, Trichoderma cavernicola differs from T. neoguizhouense by having more phialides (2–4 whorls vs 1–3 whorls) on terminal branches, bigger conidia (4–7 × 2–5 µm vs 2.5–3.2 × 2.4–3.0 µm), and bigger, variable shaped chlamydospores (4–12 × 3–10 µm vs 4.4–6.3 × 4.2–6.1 µm) ( Zhao et al. 2024). Trichoderma cavernicola differs from T. densissimum by the latter having shorter phialides (5–16 × 2–9 µm vs 5.7–8.0 × 2.5–2.9 µm), smaller conidia (4–7 × 2–5 µm vs 2.8–3.1× 2.4–2.9 µm), and large chlamydospores (4–12 × 3–10 µm vs 13.3–16.4 × 12.8–14.6 µm) ( Zhao et al. 2023). Trichoderma cavernicola differs from T. paradensissimum by the latter having green to yellow and white pustules formed inconspicuously zonate, can produce yellowish pigment, solitary or 3 phialides on terminal branches, and smaller conidia (4–7 × 2–5 µm vs 2.7–3.0 × 2.5–2.9 µm) ( Zhao et al. 2023). Trichoderma cavernicola differs from T. afroharzianum by the latter having 1–5 whorls with phialides, narrower and smaller supporting cells (4– 22 × 2–8 µm vs 2.2–3.2 µm wide), smaller conidia (4–7 × 2–5 µm vs 2.7–3.5× 2.5–3.2µm), and rare chlamydospores ( Chaverri et al. 2015). Based on the phylogenetic analyses and morphological characteristics, Trichoderma cavernicola is described as a new species.

Figures

FIGURE 1. RAxML tree based on a combined dataset of ITS, RPB2, and TEF1-α partial sequences.Bootstrap support values for maximum likelihood (ML) equal to or higher than 60% and Bayesian probability (BYPP) equal to or higher than 0.90 are mentioned above the branches (ML/BI). Newly generated sequences in this study are in blue and red. Type strains are denoted with T.

FIGURE 3. Trichoderma cavernicola (holotype, GMB-W1117). A, B Colony on PDA (above and below). C Sporulation on PDA (35 days old culture). D–I Conidiophores, phialides and conidia. J Chlamydospores. K Conidia. Scale bars: D–J = 20 μm, G, K = 10 μm.