Diaporthe leshanensis X. Y. Li & C. L. Yang, 2025

Li, Xinyue, Xu, Xiulan, Xiang, Shasha, Liu, Feng, Wang, Feihu, Jiang, Xuejing, Liu, Yinggao & Yang, Chunlin, 2025, Morpho-phylogenetic evidence reveals two new species and two new host records of Diaporthe (Diaporthales, Diaporthaceae) from Phellodendron chinense in Sichuan, China, MycoKeys 123, pp. 205-233 : 205-233

Diaporthe leshanensis X. Y. Li & C. L. Yang sp. nov.

Fig. 4

Etymology.

Referring to the collection site: Leshan City in Sichuan Province, China.

Description.

Saprobic on decaying branch of Phellodendron chinense . Sexual morph: Not observed. Asexual morph: Coelomycetous. Conidiomata 323–409 × 231–254 μm (x ̄ = 370 × 244 μm, n = 10), immersed in bark, scattered, erumpent, discoid, with a solitary undivided locule. Conidiomatal wall 11–23 μm wide, parenchymatous, consisting of multi-layered pale brown, thick-walled cells of textura angularis or textura globulosa. Conidiophores reduced to conidiogenous cells. Conidiogenous cells 6.7–12.3 × 1.2–3.2 μm (x ̄ = 8.7 × 2.3 μm, n = 20) for producing alpha-conidia, 7.1–11.2 × 1.2–2.2 μm (x ̄ = 9 × 1.6 μm, n = 20) for producing beta-conidia, terminal, enteroblastic, cylindrical, slightly tapering towards the apex. Alpha-conidia 6.6–10 × 2.1–3.2 μm (x ̄ = 8.3 × 2.6 μm, n = 50), hyaline, straight, ovate to ellipsoidal, aseptate, thin-walled, base sub-truncate, usually with 2–5 guttules. Beta-conidia 19.7–22.5 × 1.3–1.7 μm (x ̄ = 21.1 × 1.5 μm, n = 50), hyaline, aseptate, filiform, curved, tapering towards both ends. Gamma-conidia not observed.

Culture characteristics.

Alpha-conidia germinated in sterile water within 24 h at 25 ° C. Colonies on PDA reached 40–50 mm in diameter after 7 d at 25 ° C, with abundant, irregularly distributed, flocculent aerial mycelium. Colony surface grey-green, becoming darker with age, texture cottony to floccose, margin irregular and moderately lobate, elevation low to moderately raised. Colony density moderate to high, with sporulation observed after 30 d, producing abundant alpha-conidia. Reverse dark brown to light brown with uneven pigmentation forming an interlaced pattern.

Material examined.

• China, Sichuan Province, Leshan City, Jinkouhe County, Jixing Village , 29°16'58.10"N, 103°13'7.42"E, 1599 m elev., from branches of Phellodendron chinense , 1 May 2024, X. Y. Li, LXY 202405010 A ( SICAU 25-0158 , holotype), ex-type culture ( SICAUCC 25-0130 ) . ibid., LXY 202405010 B ( SICAU 25-0157 ), culture ( SICAUCC 25-0129 ) .

Notes.

Phylogenetic analysis of combined ITS, tef 1 - α, tub 2, cal and his 3 sequence data revealed that Diaporthe leshanensis formed a separate clade sister to D. phellodendri (100 % MLBS / 1.00 BYPP; Fig. 1 ) and nested with D. eucommiigena and D. passiflorae . Morphologically, conidiogenous cells of D. leshanensis are shorter than those of D. phellodendri (14.1–30.4 × 1.4–2.8 μm vs. 7.1–11.2 × 1.2–2.2 μm for producing beta-conidia). Compared to D. passiflorae , D. leshanensis possesses larger alpha-conidia (6.6–10 × 2.1–3.2 μm vs. 5.5–7 × 2–3 μm) and beta-conidia (19.7–22.5 × 1.3–1.7 μm vs. 16–18 × 1.5 μm) ( Crous et al. 2012). In addition, the beta-conidia of D. leshanensis are smaller than those of D. eucommiigena (19.7–22.5 × 1.3–1.7 μm vs. 27–37 × 1–2 μm) ( Wang et al. 2022). Pairwise nucleotide comparisons further support the distinction of D. leshanensis from related taxa. Diaporthe leshanensis ( SICAUCC 25-0130 , holotype) differs from D. phellodendri ( SICAUCC 25-0174 , holotype) by 0.21 % (1 / 482, 0 gap) differences in ITS, 3.85 % (8 / 208, 2 gaps) differences in tef 1 - α, 1.22 % (5 / 410, 0 gap) differences in tub 2 and 34.6 % differences (127 / 367, 2 gaps) in his 3. Furthermore, sequence data between D. leshanensis and D. passiflorae ( CBS 132527 , holotype) showed 3.11 % (15 / 482, 1 gap), 23.63 % (60 / 254, 36 gaps), 2.48 % (10 / 404, 0 gap), 5.02 % (16 / 319, 0 gap) and 34.19 % (133 / 389, 9 gaps) differences in ITS, tef 1 - α, tub 2, cal and his 3, respectively. Additional comparisons showed that D. leshanensis differs from D. eucommiigena ( GUCC 420.9 ) by 2.39 % (12 / 482, 1 gap) in ITS, 21.77 % (54 / 248, 30 gaps) in tef 1 - α and 3.11 % (14 / 450, 1 gap) in tub 2. Hence, based on its morphological characteristics, phylogenetic analysis, and nucleotide polymorphism comparison, D. leshanensis is described here as a new species.

Figures

Figure 1. Maximum Likelihood phylogenetic tree, based on concatenated sequences of the ITS, tef 1 - α, tub 2, cal and his 3 gene regions from Diaporthe species. Bootstrap support values ≥ 60 % (left) and Bayesian posterior probabilities ≥ 0.90 (right) are shown at the nodes. Isolates from the present study are indicated in bold. Ex-type or ex-epitype strains are marked with “ T ”.

Figure 4. Diaporthe leshanensis (SICAU 25-0158, holotype). a. Habitat of Phellodendron chinense; b, c. Conidiomata on host surface; d. Section through a conidioma; e. Ostiole; f. Conidiomatal wall; g – i. Conidiogenous cells bearing conidia; j. Alpha-conidia; k. Beta-conidia; l. Germinating alpha-conidium; m. Colony on PDA (left: above, right: reverse). Scale bars: 500 μm (c), 150 μm (d), 50 μm (e), 10 μm (f – l).