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

Fig. 6

Etymology.

Refers to the host genus Phellodendron .

Description.

Saprobic on decaying branch of Phellodendron chinense . Sexual morph: Not observed. Asexual morph: Coelomycetous. Conidiomata 257–291 × 211–240 μm (x ̄ = 271 × 223 μm, n = 10), immersed, discoid to conical or irregular, brown to dark brown, solitary, scattered, unilocular. Conidiomatal wall 17–40 μm wide, parenchymatous consisting of multi-layers of pale brown to reddish-brown, thick-walled cells of textura angularis or textura globulosa. Conidiophores hyaline, smooth, straight to flexural, basally branched or unbranched. Conidiogenous cells 6.7–37 × 1.2–2.7 μm (x ̄ = 18.7 × 1.8 μm, n = 20) for producing alpha-conidia, 14.1–30.4 × 1.4–2.8 μm (x ̄ = 22.1 × 1.9 μm, n = 20) for producing beta-conidia, terminal, enteroblastic, monophialidic, cylindrical, slightly tapering towards the apex. Alpha-conidia 6.6–9.7 × 1.9–3.2 μm (x ̄ = 8.1 × 2.6 μm, n = 50), hyaline, straight, ovate to ellipsoidal, aseptate, thin-walled, base sub-truncate, usually with two guttules. Beta-conidia 16.3–27.1 × 1.5–1.7 μm (x ̄ = 20.4 × 1.6 μm, n = 50), hyaline, aseptate, filiform, curved, tapering towards both ends, scattered amongst the alpha conidia. Gamma-conidia not observed.

Culture characteristics.

Alpha-conidia germinated in sterile water within 24 h at 25 ° C. Colonies on PDA attaining 40–50 mm diam. in 7 d. Colony irregular, with a fimbriate margin, mycelium sparse, surface floccose to cottony. Initially producing white aerial mycelium appressed to the medium surface, later developing into off-white to greyish-white colonies. Colony slightly raised, highest at the centre and gradually lower towards the margin. Reverse pale yellow with uneven pigmentation. Sporulation observed after approximately 20 d in culture, forming pale yellow to brown conidial masses irregularly distributed across the colony.

Material examined.

• China, Sichuan Province, Yibin City, Junlian County, Haoba Village , 27°55'20.16"N, 104°33'23.89"E, 1337 m elev., from branches of Phellodendron chinense , 2 May 2024, X. Y. Li, LXY 202405030 A ( SICAU 24-0065 , holotype), ex-type culture ( SICAUCC 23-0174 ) ; ibid., LXY 202405030 B ( SICAU 24-0066 ), culture ( SICAUCC 23-0175 ) .

Notes.

In the phylogenetic analysis, Diaporthe phellodendri formed a well-supported clade (100 % MLBS / 1.00 BYPP; Fig. 1 ), showing its closest affinities to D. eucommiigena , D. passiflorae and D. leshanensis . Morphologically, D. phellodendri differs from D. passiflorae by having larger alpha conidia (6.6–9.7 × 1.9–3.2 μm vs. 5.5–7 × 2–3 μm), as well as larger beta conidia (16.3–27.1 × 1.5–1.7 μm vs. 16–18 × 1.5–2 μm) ( Crous et al. 2012). In contrast to D. eucommiigena , D. phellodendri produces smaller beta conidia (16.3–27.1 × 1.5–1.7 μm vs. 27–37 × 1–2 μm) ( Wang et al. 2022). Pairwise nucleotide comparisons further support the distinctiveness of D. phellodendri . It differs from D. passiflorae ( CBS 132527 , holotype) by 2.78 % in ITS (16 / 575 bp, 1 gap), 19.57 % in tef 1 - α (45 / 230 bp, 8 gaps), 3.75 % in tub 2 (16 / 427 bp, 0 gap) and 7.69 % in his 3 (31 / 403 bp, 6 gaps). In comparison with D. eucommiigena ( GUCC 420.9 , holotype), D. phellodendri shows sequence divergence of 2.26 % in ITS (13 / 574 bp, 1 gap), 20.58 % in tef 1 - α (50 / 243 bp, 8 gaps) and 3.06 % in tub 2 (14 / 457 bp, 1 gap). In addition, D. phellodendri is clearly separable from D. leshanensis , with diagnostic characters provided in the description of the latter. Therefore, D. phellodendri is described as a new species within Section Sojae.

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 6. Diaporthe phellodendri (SICAU 24-0065, holotype). a. Habitat of Phellodendron chinense; b, c. Conidiomata on host surface; d. Section through a conidioma; e. Ostiole; f. Conidiomatal wall; g – j. Conidiogenous cells bearing conidia; k. Alpha-conidia; l. Beta-conidia; m. Germinating alpha-conidium; n. Colony on PDA (left: above, right: reverse). Scale bars: 200 μm (c), 50 μm (d), 30 μm (e, f), 10 μm (g – m).