Diaporthe orixae Q.T. Lu & Z. Zhang, 2022

Lu, Qing-Tao, Zhang, Jing-Yi, Sun, Ya-Ru, Tang, Xia, Lu, Yong-Zhong & Zhang, Zhen, 2022, Diaporthe orixae sp. nov., an endophytic species isolated from Orixa japonica in southern China, Phytotaxa 544 (1), pp. 37-51 : 45-46

Diaporthe orixae Q.T. Lu & Z. Zhang , sp. nov. FIGURE 2

Index Fungorum number: IF558801; Facesoffungi number: FoF 10496

Etymology: Name referring to the host “ Orixa japonica ”, using the genitive case meaning “of Orixa ”.

Holotype: HKAS 121465

Endophytic in the stems of Orixa japonica . Sexual morph: Undetermined. Asexual morph: Conidiomata 98–509 μm × 55–360 μm, superficial or immersed in MEA culture media, pycnidial, globose to conical, gregarious scattered or aggregated, brown to dark brown, ostiolate, with short necks, 36–88 μm × 49–73 μm, outer surface smooth or covered by sparse hyaline hyphae; pycnidial wall consisting of brown, thick-walled cells of textura angularis. Conidiophore hyaline, subcylindrical to cylindrical, formed from the inner layer of the locular wall, reduced to conidiogenous cells, rarely septate. Conidiogenous cells 2.0–4.2 μm × 1.0–2.5 μm, hyaline, subcylindrical to cylindrical, rarely tapering towards the apex, collarette present and not flared, with prominent periclinal thickening. Alpha conidia 3.5–5.5 μm × 1.5–3.0 μm, hyaline, oblong to ellipsoid, apex bluntly rounded, base obtuse; small guttulate at the top, middle and base of alpha conidia. Beta and gamma conidia absent.

Culture characteristics: Colonies on MEA medium at 26°C, surface mycelium dense and felty, buff or off white, mycelium radiate outward from the centre with feathery branches at margin; reverse pale yellow to pale brown grey, fading gradually from the centre to the edge. Conidiomata distributed in the dish irregularly.

Material examined: CHINA, Guizhou Province, Qingzhen city, from the healthy stems of Orixa japonica , 14 Sep 2020, Hong-Bo Wang, JJ 3 (Holotype: HKAS 121465 , dried culture), ex-type living culture: KUNCC 21–10714, ibid., 14 Sep 2020, Hong-Bo Wang, JJ 18 (paratype: GZAAS 21–0392 ), living culture GZCC 21–1085 .

Notes: Two obtained cultures (KUNCC 21–10714 and GZCC 21–1085) isolated from the healthy stems of Orixa japonica , are identified to represent a new species of Diaporthe orixae which cluster closer to D. sackstonii and D. caryae with a high bootstrap support values (99% ML-bs, 1.00 BYPP and 74% MP-bs) in the phylogenetic tree. Based on pairwise nucleotide comparisons, D. orixae is different from D. caryae in 20/622 bp (3%) of ITS, 7/577bp (1.2%) of tef1-α, 17/749 (2.3%) of β-tub and 14/590 (2.4%) of his3 and differs from D. sackstonii in 23/566 bp (4%) of ITS, 9/587bp (1.5%) of tef1-α and 7/773 (0.9 %) of β-tub. They also can be distinguished by morphological characters. Diaporthe orixae has bigger conidiomata compared to D. caryae (98–509 μm versus 310–325 μm diam); smaller alpha conidia (3.6–5.6 × 1.7–2.7 μm versus 7–8.5 × 2.1–2.5 μm), however, the beta conidia of D. orixae is absent, but D. caryae produced. Diaporthe orixae has bigger conidiomata compared to D. sackstonii (98–509 μm versus 50–100 μm diam), smaller necks (36–88 μm versus up to 500 μm), smaller conidiogenous cells (2.0–4.2 × 1.2–2.6 μm versus 10–15 ×1.5–3.0 μm) and smaller alpha conidia (3.6–5.6 × 1.7–2.7 μm versus 6–8 × 2–2.5 μm). Based on the combination of morphological characterization and multi-gene phylogeny, we introduce D. orixae as a distinct species according to the guidelines for species delineation described in Jeewon & Hyde (2016). The paratype of D. orixae (GZCC 21–1085), did not produce micro-morphologic structures in the media.

Figures

FIGURE 2. Diaporthe orixae (HKAS 121465, holotype) a Host. b Stem of Orixa japonica. c, d Colonies on MEA. e Conidiomata. f, g Section through conidiomata. h, i Peridium. j–m Conidiogenous cells and conidia. n Alpha conidia. Scale bars: f = 50 µm, g = 100 µm, h–n = 10 µm.