Trichoderma densissimum C.L. Zhang, 2023

Zhao, Rui, Mao, Li-Juan & Zhang, Chu-Long, 2023, Three new species of Trichoderma (Hypocreales, Hypocreaceae) from soils in China, MycoKeys 97, pp. 21-40 : 21

Trichoderma densissimum C.L. Zhang sp. nov.

Fig. 3

Etymology.

The Latin specific epithet " densissimum " refers to the thick wall of chlamydospores of this species.

Diagnosis.

It is easily distinguished from these related species by its relatively large chlamydospores (11.7-)13.3-16.4 (-19.5) × (11.5-)12.8-14.6-12.8 (-16.0) μm (mean = 14.8 × 13.6 μm) (n = 30).

Type.

China: Shandong Province, Weifang City , 36°38'27"N, 119°01'21"E, 80 m alt., isolated from soils of apple tree rhizosphere. Oct 2015, Y. Jiang T32434 (Holotype CGMCC 3.24126, stored in a metabolically inactive state. Ex-type culture CGMCC 3.24126) .

Description.

Optimum temperature for growth is 30 °C on CMD, MEA and SNA and 25 °C on PDA. Growth slow at 35 °C on PDA and SNA. Chlamydospores are common on all media.

Colony radius on CMD after 72 h: 38-45 mm at 25 °C, 55-62 mm at 30 °C, 42-43 mm at 35 °C. Colonies well-defined, white, thin, aerial hyphae sparse. Conidiation was noted after 2 d around the inoculation plug, which was white at first, turning yellow green after 3-4 d, then dark green after 5-6 d. Conidiation formed 4 obvious concentric zones. No diffusing pigment noted, odor indistinct. Chlamydospores common single, sometimes terminal and intercalary, globose to subglobose, (11.7-)13.3-16.4(-19.5) × (11.5-)12.8-14.6-12.8(-16.0) μm (mean = 14.8 × 13.6μm); with length/width ratio of 1.0 × 1.3 (mean = 1.1) (n = 30).

Colony radius on PDA after 72 h: 61-66 mm at 25 °C, 60-63 mm at 30 °C, 24-31 mm at 35 °C. Colony white, regularly circular, distinctly zonate; mycelium dense and radial. Conidiation in the form on pustules, yellow-green, relatively abundant in the zonation regions. No diffusing pigment noted, odor indistinct.

Colony radius on MEA after 72 h: 62-63 mm at 25 °C, 66-67 mm at 30 °C, 44-47 mm at 35 °C. Colonies similar to that on PDA, but indistinctly zonate. No diffusing pigment noted, odor indistinct.

Colony radius on SNA after 72 h: 53 mm at 25 °C, 41-47 mm at 30 °C, 27-32 mm at 35 °C. Colony white; aerial mycelia scant and loose. Conidiation in the form of minute pustules, radial and inconspicuously zonate. No diffusing pigment noted, odor indistinct. Conidiophores pyramidal with opposing branches, the main axis with side branches is sometimes at right angles or inclined upward. The main axis and each branch commonly terminating verticillate, whorl of 3-4 phialides, sometimes in a cruciate whorl, sometimes solitary phialides. Phialides commonly ampulliform, sometimes ampulliform to subglobose (3.4-)5.7-8.0(-10.1) × (1.9-)2.5-2.9(-3.2) μm (mean = 6.2 × 2.6μm), base (1.0-)1.4-2.1(-2.6) μm (mean = 2.2 μm); phialide length/width ratio (1.4-)2.1-3.2(-3.9)(mean = 2.6) (n = 30). Conidia subglobose to globose, green, (2.3-)2.8-3.1(-3.4) × (2.2-)2.4-2.9(-3.3) μm (mean = 2.9 × 2.7 μm), with length/width ratio of 1.0-1.4 (mean = 1.1) (n = 30).

Sexual morph.

Unknown.

Substrate.

Soil.

Distribution.

China, Shandong and Shanxi provinces.

Additional material examined.

China: Shandong Province, Jinan City , 36°32 ’33” N, 117°01 ’08” E, 201 m alt., isolated from soils of wheat, Jun 2015, Y. Jiang ( T31818 ) ; Shandong Province, Jining city, 34°56 ’21” N, 116°29 ’03” E, 34 m alt., isolated from soils of peach, Aug 2015, Y. Jiang T32353 ; Shaanxi Province, Baoji city, 34°23 ’25” N, 107°10 ’18” E, 802 m alt., isolated from soils of corn, Aug 2015, Y. Jiang T32465 .

Notes.

Although T. densissimum , T. paradensissimum and T. guizhouense share similar conidia and pyramidal conidiophores, T. densissimum cannot produce pigments while T. paradensissimum and T. pholiotae can produce yellowish pigment on PDA and CMD at 35 °C in the dark ( Li et al. 2013; Cao et al. 2022). Characterized by producing globose to subglobose chlamydospores, the chlamydospores of T. simile are elliptic or round, unobserved in T. guizhouense and T. asiaticum ( Jaklitsch and Voglmayr 2015; Zheng et al. 2021).

Figures

Figure 3. Cultures and anamorph of T. densissimum strain T 32434 a-d cultures on different media at 25 ° C with a 12 h light and 12 h darkness cycle after 7 d (a on PDA b on MEA c on CMD d on SNA) e conidiation pustules on PDA after 7 d g, i-l conidiophores and phialides (g, i-k on CMD 3 d l on SNA 3 d) f chlamydospores h conidia. Scale bars: 10 μm (f-l).