Trichoderma foliatum G. S. Jin & Z. X. Zhu sp. nov.

Fig. 4

Etymology.

From Latin foliatus (= lobed, leaf-like), referring to the irregularly lobed colony margin on PDA.

Diagnosis.

Slow-growing on PDA, colonies with irregularly lobed margins; green pustules produced after 3–4 days. On CMD, colonies forming a loose concentric annular pattern.

Typification.

China • Jilin Province, Changchun City, Shuangyang District, 43°21'5"N, 125°53'43"E, 337 m alt., on rotten wood, 31 Jul. 2025, Z. X. Zhu, G. S. Jin, B. Liang, M. Y. Zhu, G. L. Zhao 2181 (Holotype HMJAU 34755, ex-type culture CGMCC 7.672).

Sexual morph.

Unknown.

Cultures and asexual morph.

On PDA at 25 ° C, colony radius 6–8 mm after 72 h, reaching 42–44 mm after 3 weeks. Colonies white, often divided into several fissured segments, margin initially circular and becoming dentate or lobed with growth, with fertile aerial hyphae. Conidiation appearing after 3–4 days; pustules contiguous, initially pale white, becoming dark green with age. Conidiophores trichoderma-like, arising in whorls of 2–5 phialides or with solitary phialides along the main axis. Phialides straight, lageniform to subulate, (5.1 –) 6–11.4 (– 12.7) × (2.2 –) 2.4–3.4 (– 3.7) μm (n = 30), l / w (1.5 –) 2.1–4.2 (– 4.7), 1.4–2.7 μm wide at the base (n = 30). Conidia green, subglobose to globose or ellipsoidal, (2.2 –) 2.6–4 × 2.1–3.3 (– 3.7) μm (n = 30), l / w (0.7 –) 1–1.4 (– 1.7). Odor absent; no pigment observed.

On CMD at 25 ° C, colony radius 12–14 mm after 72 h, with the plate fully covered after 15 days. Colonies white, with rare aerial hyphae. Conidiation appearing after 15 days; pustules green, disposed in a loose concentric annular pattern. Odor absent; no pigment observed.

On SNA at 25 ° C, colony radius 6–8 mm after 72 h, with the plate fully covered after 25 days. Colonies white, with rare aerial hyphae. Conidiation appearing after 7 days; pustules loosely scattered along the inner margin of the colony. Chlamydospores absent. Odor absent; no pigment observed.

Notes.

Trichoderma foliatum produces colonies with irregularly lobed margins on PDA, resembling those of T. aureoviride and T. estonicum. However, T. foliatum exhibits a markedly slower growth rate (6–8 mm after 72 h), similar to T. aureoviride (4–5 mm after 72 h) but clearly distinct from T. estonicum (29–31 mm after 72 h). The combination of slow vegetative growth and early, well-developed pustule formation represents an uncommon character state within Trichoderma (Jaklitsch 2009).

Phylogenetically, T. foliatum is resolved as a distinct lineage within the Harzianum clade. It differs from its closest GenBank BLAST result, T. ceramicum (CBS 114576), by 66 nucleotide substitutions in the rpb 2 locus (969 bp), corresponding to an overall sequence similarity of approximately 93 %, supporting its recognition as a distinct species.