Diatrypella thailandica Rathnayaka, K. D. Hyde & Chethana, 2025

Rathnayaka, Achala R., Chethana, K. W. Thilini, Manowong, Areerat, Bhagya, Amuhenage T., Win, Hsan, Tun, Zaw L., Mapook, Ausana & Hyde, Kevin D., 2025, Taxonomy, phylogeny, and bioactive potential of Xylariales (Sordariomycetes, Ascomycota) from Thailand: novel species discovery, new host and geographical records, and antibacterial properties, MycoKeys 120, pp. 35-117 : 35-117

Diatrypella thailandica Rathnayaka, K. D. Hyde & Chethana sp. nov.

Fig. 18

Etymology.

The epithet thailandica refers to Thailand, from where the fungus was collected.

Holotype.

MFLU 24-0533 .

Description.

Saprobic on a dead branch of Fabaceae sp. Sexual morph: Stromata 0.5–1 mm in diam., well-developed, with groups of 10–15 perithecia, solitary to gregarious, erumpent, black, immersed, globose to subglobose or conical shape. Endostroma white to light yellow. Ascomata 410–450 μm high × 275–370 μm diam. (x ̄ = 434 × 326 μm, n = 10), perithecial, immersed in stromata, 2–4 perithecial arrangement, subglobose, with an individual ostiole. Ostiolar canal 200–253 μm high, 110–132 μm diam., cylindrical, periphysate, with yellowish pigment around ostioles. Peridium 10–25 μm wide, composed of 3–7 layers, hyaline to brown, thick-walled cells of textura angularis. Hamathecium 2.4–6 μm wide, comprising dense, hyaline, aseptate, unbranched paraphyses, tapering towards the apex, embedded in a hyaline gelatinous matrix. Asci 80–150 × 11–23 μm (x ̄ = 107 × 16 μm, n = 25), polysporous, unitunicate, clavate to cylindric-clavate, with a J-apical ring and a long pedicel. Ascospores 6–8 × 1–3 μm (x ̄ = 7.5 × 2.3 μm, n = 30), multi-seriate, crowded, initially hyaline, becoming pale yellowish at maturity, oblong to allantoid, aseptate, slightly curved, smooth-walled, mostly with small guttules. Asexual morph: Undetermined.

Culture characteristics.

Ascospores are germinated on the PDA within 24 hours at 25 ° C. Germ tubes are produced from both sides of the ascospore. Colonies on the PDA at 25–28 ° C reach 2 cm in 10 days, medium dense, circular to slightly irregular, cottony, white at first, becoming light brownish yellow in the front view, and pale yellow in the reverse view.

Material examined.

Thailand • Chiang Rai, Nang Lae village , on a decaying branch of Morus sp. ( Moraceae ), 18 March 2024, Achala Rathnayaka, AA 14 ( MFLU 24-0533 , holotype) ; ibid., on a dead branch of Fabaceae sp. ( Fabaceae ), 20 March 2024, Achala Rathnayaka, AA 15 ( MFLU 24-0534 , topotype) .

Notes.

Our new fungal collection ( MFLU 24-0533 and MFLU 24-0534 ) fits within Diatrypella by having conical-shaped stromata, white to light yellow, well-developed endostroma, cylindrical, polysporous, and long-stalked asci, and hyaline to yellowish ascospores ( Hyde et al. 2020 a). According to the multi-gene phylogenetic analyses (ITS and β-tub), our strains ( MFLU 24-0533 and MFLU 24-0534 ) formed a separate clade sister to D. oregonensis ( CA 117 , DPL 200 ), D. pseudooregonensis ( GMB 0039 , GMB 000 ), and D. verruciformis ( UCROK 1467 , UCROK 754 ) with 93 % ML bootstrap and 0.94 PP support (Fig. 17 ). Morphologically, D. thailandica differs from D. oregonensis , D. pseudooregonensis , and D. verruciformis , as mentioned in Table 2 . Diatrypella thailandica has polysporous asci, while D. oregonensis and D. pseudooregonensis have 8 - spored asci. Diatrypella verruciformis differs from our fungal collection by having diamond- or star-shaped ascomata (Table 2 ). When comparing the ITS and β-tub base pairs (without gaps) between D. thailandica ( MFLU 24-0533 ) with D. oregonensis ( CA 117 ), D. pseudooregonensis ( GMB 0039 ), and D. verruciformis ( UCROK 1467 ), there are 2.15 % (11 / 512), 3.3 % (16 / 485), and 2.73 % (14 / 512) base pair differences in the ITS and 2.17 % (18 / 828), 2.53 % (21 / 828), and 1.7 % (14 / 828) for β-tub, respectively. Based on both morphological and molecular evidence, we introduce Diatrypella thailandica ( MFLU 24-0533 ) as a new species in Diatrypella .

Figures

Figure 17. Phylogram generated from ML analysis based on the combined dataset of ITS and β-tub. The tree is rooted to Kretzschmaria deusta (CBS 826.72) and Xylaria hypoxylon (CBS 122620). Bootstrap support values for ML ≥ 70 % and Bayesian posterior probabilities (PP) ≥ 0.90 are noted at the nodes. Strain numbers are noted after the species names. Strains isolated in this study are presented in blue, and type strains are in bold.

Figure 18. Diatrypella thailandica on a dead branch of Fabaceae sp. (MFLU 24-0533, holotype) a. Substrate; b, c. Stromata on the substrate; d. Cross-section of a stroma; e. Vertical section through stroma showing ostiole and perithecia; f. Ostiole; g. Peridium; h. Paraphyses; i – l. Asci; m. Apical apparatus in Melzer’s reagent; n – q. Ascospores. Scale bars: 2 mm (b); 500 μm (c); 200 μm (d); 100 μm (e, f); 10 μm (g); 20 μm (h – m); 5 μm (n – q).