Trichoderma tardum 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 : 39-43

Trichoderma tardum K. Chen & W.Y. Zhuang , sp. nov. Fig 7

Fungal Names: FN570278.

Etymology: The specific epithet refers to slow growth of the fungus.

Diagnosis. Colony growing very slow on CMD, PDA and SNA at 25 °C. Conidiophores acremonium-like to verticillium-like, phialides lageniform, conidia green, globose to subglobose.

On CMD after 72 h colony radius 8 mm and mycelium covering the plate after 40 d at 25 °C. Colony hyaline, margin slightly lobed, aerial hyphae inconspicuous. No conidiation noted within 30 d. No chlamydospores observed. No distinct odor, no diffusing pigment observed.

On PDA after 72 h colony radius 12–13 mm and mycelium covering the plate after 24 d at 25 °C. Colony white, margin not well defined, aerial hyphae numerous. No conidiation noted within 30 d. Chlamydospores rare. No distinct odor, no diffusing pigment observed.

On SNA after 72 h colony radius 3 mm and mycelium not covering the plate within 40 d at 25 °C. Colony hyaline, inconspicuous, margin not well defined, aerial hyphae nearly lacking. Conidiation noted after 15 d, formed on short erect conidiophores and aerial hyphae. Conidiophores simple, acremonium-like to verticillium-like, unbranched with solitary phialides or with few simple branches inclined upwards. Phialides formed solitary, less commonly in whorls of 2–3, lageniform, (6.2–)9.0–13.1 × (1.4–)2.1–4.1(–5.0) μm, l/ w 2.5 –6.0(–9.0), 1.4–2.8 μm wide at the base (n = 30). Conidia green, globose to subglobose, 3.1–4.3 × 3.1–4.3 μm, l/ w 1.0 –1.2 (n=40). Chlamydospores numerous. No distinct odor, no diffusing pigment observed.

Strains examined: CHINA. Hubei: Shennongjia, elev. 2816 m, isolated from soil, 19 November 2014, K. Chen TC199 (holotype HMAS 248798, ex-type culture CGMCC 3.18320). ibid., K. Chen TC242 (HMAS 248799).

Notes: Trichoderma tardum is most similar to T. oligosporum in slow growth rates on all three media, and scant conidia on CMD and PDA at 25 °C. The conidia of T. tardum are green while that of T. oligosporum are hyaline ( Zhu & Zhuang 2015). As to phylogenetic positions, T. oligosporum belongs to the Psychrophilum clade other than Viride clade. Although T. caerulescens is sister of T. tardum , it differs in much faster growth rates (30–41mm on CMD, 27– 36mm on PDA, 24–30mm on SNA at 25 °C after 72 h), forming numerous conidia on CMD and PDA, and giving rise to blue pigments on CMD ( Jaklitsch et al. 2012). The distinctions between T. tardum and T. bifurcatum were already discussed above.

Figures

FIGURE 7. Trichoderma tardum (HMAS 248798). A–C. Cultures after 25 d at 25 °C (A. CMD; B. PDA; C. SNA); D–K. Conidiophores and phialides (SNA, 25 d); L–M. Chlamydospores (SNA, 25 d); N–O. Conidia (SNA, 25 d). Scale bars:A–C = 20 mm; D–J, M = 10 μm; K, L, N, O = 5 μm.