Trichoderma bifurcatum K. Chen & W.Y. Zhuang, 2017

Chen, Kai & Zhuang, Wen-Ying, 2017, Seven soil-inhabiting new species of the genus Trichoderma in the Viride clade, Phytotaxa 312 (1), pp. 28-46 : 36

Trichoderma bifurcatum K. Chen & W.Y. Zhuang , sp. nov. Fig 4

Fungal Names: FN570277.

Etymology: The specific epithet refers to the bifurcate arrangement of phialides.

Diagnosis. Colony fast-growing on CMD and PDA, slow-growing on SNA at 25 °C. Phialides narrowly lageniform, conidia green, globose to subglobose, less commonly ellipsoid.

On CMD after 72 h colony radius 38–39 mm and mycelium covering the plate after 6 d at 25 °C. Colony hyaline, loose, radial, margin well defined, aerial hyphae common, more abundant with distance from the original inoculum. Conidiation noted after 10 d, effuse in aerial hyphae or on small pustules, pustules yellow-greenish, formed on aerial hyphae, denser at colony margin. Conidiophores with or without main axis, branches paired or unpaired, rebranching up to 4 times. Phialides formed at the tips of branches and most in pairs or less commonly solitary, narrowly lageniform, 8.3–12.2(–17.9) × 2.1–3.9 μm, l/ w 1.9 –5.3(–7.0), 1.7–3.1 μm wide at the base (n = 40). Conidia green, globose to subglobose, less commonly ellipsoid, 3.3–4.7(–6.4) × 3.3–4.4 μm, l/ w 1.0 –1.2(–1.4) (n=40). Chlamydospores rare. No distinct odor, no diffusing pigment observed.

On PDA after 72 h colony radius 34–36 mm and mycelium covering the plate after 5 d at 25 °C. Colony white, radial, margin well defined, aerial hyphae abundant, coilings frequent. Conidiation noted after 5 d, effuse in aerial hyphae, not common. No chlamydospores observed. No distinct odor, no diffusing pigment observed.

On SNA after 72 h colony radius 6–7 mm and mycelium covering the plate after 21 d at 25 °C. Colony hyaline, loose, indistinctly zonate, margin slightly lobed and well defined, aerial hyphae common, appearing along 2–3 concentric zones, coilings frequent. Conidiation noted after 7 d, effused on short erect conidiophores and aerial hyphae, denser at the colony margin. No chlamydospores observed. No distinct odor, no diffusing pigment observed.

Strains examined: CHINA. Hubei: Shennongjia, elev. 2352 m, isolated from soil, 19 November 2014, K. Chen TC162 (holotype HMAS 248795, ex-type culture CGMCC 3.18318).

Notes: That most phialides are arranged in pairs is a conspicuous and diagnostic feature of this species. The two terminal phialides are usually bifurcate, which is rarely seen in the genus. Fig 1 reveals that T. bifurcatum is closely related to T. tardum , whereas the latter fungus differs in much slower growth rates and a different pattern of conidiogenous cell arrangement. Trichoderma caerulescens as a sister of T. bifurcatum forms verticillium-like conidiophores, and grows much faster (24–30 mm) on SNA at 25 °C ( Jaklitsch et al. 2012).

Figures

FIGURE 1. One of the most parsimonious trees based on the analysis of the combined RPB2 and TEF1 matrix, showing phylogenetic positions of the new species. From left to right: MPBP above 50%, MLBP above 70%, and BIPP above 90% are provided at the nodes.

FIGURE 4. Trichoderma bifurcatum (HMAS 248795). A–C. Cultures at 25 °C (A. CMD, 25 d; B. PDA, 7 d; C. SNA, 20 d); D–E. Conidiation pustules (CMD, 25 d); F–N. Conidiophores and phialides (PDA, 5 d); O–Q. Conidia (CMD, 25 d). Scale bars:A–C = 20 mm; D–E = 200 μm; F = 20 μm; G–I = 10 μm; J–Q = 5 μm.