Trichoderma crystalligenum W. T. Qin & W. Y. Zhuang HMAS 2017, sp. nov.

Etymology:— The specific epithet refers to the formation of crystals in culture.

MycoBank: MB 816630

Type: — CHINA. HENAN: Luoyang, Yushan, 1200 m, on rotten twigs, 23 Sep 2013, H.D. Zheng, Z.Q. Zeng & Z.X. Zhu 8880 (holotype HMAS 273783). Ex-type culture HMAS 248746.

Stromata solitary or aggregated in small groups, pulvinate, smooth, brownish yellow, 0.6–1.5 mm diam, 0.5–1.0 mm thick. Ostiolar dots obvious, numerous, dark grey to black. Rehydrated stromata turning brownish orange in 3% KOH.

In section, cortical tissue of textura angularis, 11–24 μm thick, turning brownish orange in 3% KOH, cells brownish yellow, thin-walled, 6.5–9(–13) × 4.5–6 μm (n = 30); subcortical tissue of textura intricata mixed with textura angularis, hyphae hyaline to light yellow, thin-walled, 3.5–4 μm wide, cells hyaline to light yellow, thin-walled, 4–8(–9.2) × 4–5.3(–8) μm (n = 30); subperithecial tissue of textura epidermoidea, cells hyaline to light yellow, thin-walled, 8–19(–22) × (7–)8–13(–20.5) μm (n = 30); tissue at the base of textura intricata mixed with textura angularis, hyphae hyaline to light yellow, thin-walled, (3.4–)4.7–7.4(–9) μm wide, cells hyaline to light yellow, thin-walled, 4–9 × 4–7.4 μm (n = 30). Perithecia subglobose or flask-shaped, numerous, (197–)210–250(–263) × (118–)121–176(–203) μm (n = 30); peridium yellow in lactic acid, turning orange in 3% KOH, 8–13(–15) μm thick at flanks, (8–)10.5–16 μm thick at the base (n = 30). Ostioles non-papillate or projecting up to 14 μm, 58–84(–105) μm high, (19–)24–32(–34)μm wide at the apex (n = 30). Asci cylindrical when young (no spore formation), broken easily at maturity in both young and mature perithecia, ca. 4–5.5 μm wide. Part-ascospores green, spinulose or verruculose, dimorphic, 3.8–6.2(–7.2) × (3–)3.5–4.3(–5.2) μm, l/ w 1.0 –1.5(–1.7) (n = 45).

On CMD after 72 h 59–61 mm and mycelium covering the plate after 5 d at 25 C. Colony faintly zonate with a well-defined margin. Conidiation starting in short minute shrubs first noted at the margin or sidewalls of the plate, spreading, growing to tufts or pustules, finally green. Conidiophores pachybasium-like, with phialides solitary or in whorls of 2–5 emerging from the main axes. Phialides ampulliform to lageniform, (4–)4.5–7(–8) × (2.3–)2.5–3 μm, l/w (1.4–)1.6–2.2(–2.5), 1.5–2.8 μm wide at the base (n = 50). Conidia green, ellipsoidal, smooth, (2.4–)2.7–4.3 × 2.2–3.2(–3.7) μm, l/ w 1.0 –1.5(–1.8) (n = 50). Chlamydospores terminal or intercalary, subglobose or ellipsoidal, 7–11(–14) × 6.5–11 μm, l/ w 1.0 –1.3(–1.5) (n = 50). Numerous yellow crystals formed within agar. No distinct odor, reverse brownish yellow.

On PDA after 72 h 48–50 mm; mycelium covering the plate after 5 d at 25 C. Colony dense, circle, aerial hyphae abundant and frequent, richly branched, several mm high, becoming fertile. Conidiation starting in short minute shrubs, growing to tufts or pustules, finally green. Abundant yellow crystals formed within agar. No distinct odor; reverse yellow.

On SNA after 72 h 45–47 mm and mycelium covering the plate after 6 d at 25 C. Colony hyaline, thin, fan-shaped, aerial hyphae sparsely distributed. Conidiation noted in the pustules or tufts in the margin or sidewalls of the plate, first white, turning green. No distinct odor; no diffusing pigment observed.

Notes: — Trichoderma crystalligenum is located in the Strictipile clade and closely associated with T. longipile, T. shennongjianum and T. tropicosinense, but represents an independent taxon. Trichoderma longipile is characterized by incarnate to light (orange-) red stromata with a distinctly tubercular surface and large green ascospores [distal cells (5.0–)5.5–7.3(–8.4) × (3.8–)4.2–5.0(–5.6) μm; proximal cells (5.0–)5.5–7.5(–8.4) × (3.4–)3.6–4.5(–5.0) μm] (Jaklitsch 2009). Trichoderma shennongjianum gives rise to abundant green pustules on CMD, and produces longer phialides [6.2–17 × 2.1–4.2 μm], and larger conidia [(3.6–)3.9–5.0(–5.3) × 2.8–3.9 μm] (Chen & Zhuang 2016). Trichoderma tropicosinense has dark reddish brown stromata and gliocladium-like conidiophores (Liu et al. 2003).

In the Strictipile clade, T. strictipile also produces yellowish stromata and pachybasium-like conidiophores like T. crystalligenum, but is recognizable by forming green concentric rings on PDA and wider phialides [(4.0–)7.2–7.7(– 21.7) × (2.0–)4.0–4.2(–5.7) μm] (Chaverri & Samuels 2003). Presence of yellow crystals in culture (CMD and PDA) is a diagnostic phenotypic feature of T. crystalligenum, which is known only in T. aureoviride Rifai and T. spinulosum (Fuckel) Jaklitsch & Voglmayr (Jaklitsch 2009).