Trichoderma fargesia Feihu Wang & C. L. Yang, 2025

Wang, Feihu, Xu, Xiulan, Liu, Feng, Xiang, Shasha, Li, Xinyue, Liu, Yinggao & Yang, Chunlin, 2025, Four new species of Trichoderma (Hypocreaceae, Hypocreales) discovered in the staple food bamboo of pandas, MycoKeys 124, pp. 227-248 : 227-248

Trichoderma fargesia Feihu Wang & C. L. Yang sp. nov.

Fig. 4

Etymology.

Named after the genus of the host plant from which the holotype was collected, Fargesia qinlingensis.

Holotype.

SICAU 25-0185 .

Habitat.

On the culm of Fargesia qinlingensis.

Description.

Sexual morph: Stromata scattered or aggregated in small numbers, lenticular to pulvinate in shape. Centrally attached, free margins, rounded, angular, or irregular in outline. Color ranges from light reddish-brown to dark reddish-brown, with diameters of 2–8 mm and thicknesses of 1–3 mm (n = 20). Young stromata surface velvety, covered pale yellowish hairs. Later stages, surface finely granular from perithecial contours, appearing without any covering. Ostiolar dots on stromata inconspicuous. Ascomata nearly spherical and densely arranged, measuring 150–280 × 90–240 μm (x – = 220 × 175 μm, n = 20). Ostioles flush with the stroma surface, with apical widths of 34–50 μm and heights of 45–78 μm (n = 20). Peridium ranging from hyaline to brown, lateral thickness of 4–14 μm and a basal thickness of 8–18 μm (n = 20). Asci cylindrical, measuring 65–84 × 4–6 μm (x – = 75 × 5 μm, n = 30), inclusive of a stipe 7–12 μm long, containing 16 - ascospores, apex not thickened, hyaline, cylindrical. Ascospores 3–5 × 2.5–4 μm (x – = 4.5 × 2.8 μm, n = 40) hyaline, nearly spherical to ellipsoidal. Asexual morph: Not observed.

Material examined.

China • Shaanxi Province, Ankang City, Ningshan , Primitive Forest of Fargesia qinlingensis ( 33°35'45.67"N, 108°3'54.18"E, Alt. 2280 m), 15 October 2024, Feihu Wang, WFH 202410014, ( SICAU 25-0185 , holotype) . ibid. WFH 202410014 B ( SICAU 25-0186 , paratype) .

GenBank accession numbers.

SICAU 25-0185 ( ITS: PV 789475; tef 1 - α: PV 828328; rpb 2: PV 828320); SICAU 25-0186 ( ITS: PV 789476; tef 1 - α: PV 828329; rpb 2: PV 828321).

Culture characters.

No germination was observed on potato dextrose agar ( PDA), oatmeal agar ( SNA), or malt extract agar ( MEA).

Notes.

Phylogenetically, Trichoderma fargesia strain SICAU 25-0185 and SICAU 25-0186 ) formed a distinct clade and is related to T. parahamatum ( GDMCC 3.1020 ) in the Koningii clade, but the similarities of rpb 2 and tef 1 - α between these two species were only 86.2 % and 90.5 %, respectively. During the isolation and cultivation process, T. fargesia failed to germinate in sterile water and several culture media. Trichoderma parahamatum has only been described in its asexual stage, characterized by conidiophores that are coiled, undulate, or hamate, bearing phialides that are ampulliform to subglobose, short, and wide. Conidia are subglobose, ellipsoidal to breviter cylindracea, and green. Moreover, T. parahamatum is capable of germinating in several culture media. Phylogenetic analysis indicates that the new taxon T. fargesia ( SICAU 25-0185 ) is closely related to T. parahamatum ( GDMCC 3.1020 ) (Fig. 1 ). However, our strain exhibits nucleotide differences from T. parahamatum in the rpb 2 region amounting to 13.8 % (155 / 1116, 8 gaps), 9.5 % (86 / 898, 6 gaps) differences in tef 1 - α. Pairwise nucleotide comparisons further support the distinction of T. fargesia from related taxa. The PHI test revealed no significant recombination event between our strain and the closely related taxa (Φw = 1.00) (Fig. 2 ). Trichoderma fargesia forms a distinct branch within the Koningii clade, leading to its identification as a new species.

Figures

Figure 1. Phylogram generated from maximum likelihood analysis based on combined ITS, tef 1 - α and rpb 2 sequence data of Trichoderma (koningii species complex) taxa. The species determined in this study are indicated in bold red. Bootstrap values (BS) from maximum likelihood (MLBS, left) higher than 70 BS and Bayesian posterior probabilities (BYPP, right) greater than 0.90 are given at the nodes. Hyphens (-) represent support values less than 70 MLBS / 0.90 BYPP. The ex-type strains are in T.

Figure 2. The PHI test results for Trichoderma bashania, T. fargesia, T. mianyangensis, T. yaanensis, and closely related species were obtained using both LogDet transformation and splits decomposition methods. The PHI test did not find any statistically significant recombination (Φw = 1) in the data set. The new strains are represented in red and bold. “ T ” represents the type strain.

Figure 4. Trichoderma fargesia (SICAU 25-0185, holotype). a. Appearance of ascomata on dead host; b, c. Stromata; d, e. Ascomatal tissue in section; f. Peridium; g – j. Asci; k, l. Ascospores. Scale bars: 5 mm (b); 1 mm (c); 200 µm (d); 50 µm (e); 15 µm (f – j); 5 µm (k, l).