Trichoderma speciosum Z.F. Yu & X. Du

Qiao, Min, Du, Xing, Zhang, Zhe, Xu, JianPing & Yu, ZeFen, 2018, Three new species of soil-inhabiting Trichoderma from southwest China, MycoKeys 44, pp. 63-80 : 63

Trichoderma speciosum Z.F. Yu & X. Du sp. nov. Figure 2

Etymology.

Latin, speciosum refers to showy and splendid colony on PDA.

Diagnosis.

Characterised by tree-like conidiophores, branches paired or in whorls of 3-4, spindly to fusiform phialides (5.0-10.0 × 2.0-3.0 μm), subglobose to globose conidia (3.7-4.9 × 3.1-3.8 μm). Differs from T. hispanicum by paired branches, whorled and thinner phialides, subglobose to globose conidia. Differs from T. samuelsii by paired and compact branches, subglobose to globose conidia and the character of pustules on SNA. Differs from T. junci by whorled, smaller phialides and subglobose to globose conidia.

Type.

CHINA. From soil of tobacco rhizosphere, Luliang, Yunnan Province, 24°57'22"N, 103°46'30"E, 1800 m alt., Jul 2007, Z.F. Yu (YMF 1.00205, holotype), Ex-type culture CGMCC 3.19079.

Description.

Mycelium covers plate after 72 h at 25 °C and 30 °C on CMD, no growth at 35 °C. Colony homogenous, pale yellowing, not zonate, outline circular. Aerial hyphae sparse, relatively abundant at margin, distinctly radial, arachnoid. Conidial production noted after 4 days.

On PDA, mycelium covers the plate after 72 h at 25 °C and 30 °C, no growth at 35 °C. Colony circular, typically zonate, yellow-green colony homogeneous distributed around the point of inoculation, forming a coarse circle. Whitish aerial hyphae distributed on the agar surface in external zone, hairy, dense and radial. Conidial production noted after 3 days.

On SNA after 72 h, colony radius 37-38 mm at 25 °C, mycelium covers the plate after 120 h, 56-59 mm at 30 °C after 72 h, no growth at 35 °C. Colony hyaline, thin, fan-shaped with indistinct outline. Aerial hyphae scarcely degenerating. Conidial production noted after 5 days, minute white pustules formed around central part of the colony, turning green after 6 days. Conidiophores tree-like, comprising a main axis with second branches, base 3.0-4.0 μm wide, second branches paired or in whorls of 3, sometimes second branches branched again, the distance between neighbouring second branches is (12.0-) 15.0-29.0 (-30.0) μm, main axis and branches terminating in whorls of up to five phialides. Conidiogenous cells phialides lageniform or ampulliform, arising singly or in 2-4; 5.0-10.0 × 2.0 –3.0(– 3.5) μm, length/width ratio 1.7-3.6 (-4.2), non-equilateral when curved. Conidia ovoid to short ellipsoidal, verrucose (3.6 –)3.7–4.9(– 5.0) × (3.0 –)3.1–3.8(– 4.2) μm, length/width ratio (1.0)1.1 –1.4(– 1.5).

Habitat and distribution.

In soil from tobacco rhizosphere in part of cultivated land of south-western China.

Teleomorph.

Not known

Remarks.

Trichoderma speciosum is phylogenetically most closed related to three species - T. hispanicum , T. samuelsii and T. junci ( Jaklitsch et al. 2012; Jaklitsch 2011). The three species were isolated from ascospores and only T. speciosum was isolated from the anamorph. However, T. speciosum differs from these three species in having verrucose, subglobose to globose conida, while conidia of T. hispanicum and T. samuelsii are oblong and smooth and those of T. junci are ovoid to ellipsoidal with length/width ratio 1.3 –1.8(– 2.2).

In addition, side branches of T. hispanicum are often unpaired, phialides often singly, whereas branches of T. speciosum are generally paired or in whorls of 3-5. For T. samuelsii , branches are sparser and phialides with l/w of (1.7 –)2.5–4.6(– 7.1) are more slender than those of T. speciosum . Phialides of T. junci are also more slender than those of T. speciosum , which are narrowly lageniform.