Alternaria youyangensis J.H. Huang & J.X. Deng, 2024

Huang, Jia Hui, Gou, Ya Nan, Nwe, Zin Mar, Aung, Sein Lai Lai, Deng, Jian Xin & Li, Mei Jia, 2024, Alternaria youyangensis sp. nov. (Ascomycota: Pleosporaceae) from leaf spot of Fagopyrum esculentum in China, Phytotaxa 672 (2), pp. 176-186 : 180

Alternaria youyangensis J.H. Huang & J.X. Deng sp. nov., Fig. 2

MycoBank No: 854940.

Etymology:—The epithet ‘ youyangensis ’ refers to the collecting locality, Youyang county (Chongqing, China).

Type:— CHINA, Chongqing Municipality, Youyang County, on diseased leaves of Fagopyrum esculentum , 25 October 2023, J.X. Deng (YZU-H-2023260, holotype), ex-type culture YZU 234157.

Description:— Colonies on PDA entire, white, aerial mycelium luxuriance, felty, white to grey-olivaceous, villiform, reverse light brown in the center, 53.5–54.2 mm in diam. On PCA, 7 days at 22 ℃, mycelium superficial, helical stripes, white to grey hyphae, conidiophores arising from substrate or lateral of aerial hyphae, straight or curved, dark brown; conidia 1–5 units per chain, yellow brown to dark brown, ovate, elliptic or ovoid to obpyriform, 21–52(–57) × 12–20 μm, 1–5 transverse septa, 0–2 longitudinal septa, beakless or with an apical extension (beak) around 7–15 μm. On V8A, conidiophores straight or curved, conidia 1–4 units in a chain, brown to dark brown, narrow-ovoid to ovoid, 25–47(–52)× 10–16 μm, 1–6 transverse septa, 0–2 longitudinal septa, slightly narrow at the septa, with one longitudinal or oblique or Y-shaped disto- septum in some transverse divisions, thin-walled.

Note:—Phylogenetically, Alternaria youyangensis sp. nov. falls into a unique branch within sect. Alternaria based on sequence analyses of ITS, GAPDH, TEF1, RPB2, Alt a 1, EndoPG, and OPA10-2 gene regions. The isolates of A. youyangensis were close to A. baoshanensis (ex-type, MFLUCC 21-0124), A. koreana (ex-type, SPL2-1), A. orobanches (ex-type, MFLUCC 21-0137) and A. ovoidea (ex-type, MFLU 21-0782) ( Fig. 1 ). Compared with the single gene sequence between A. youyangensis isolates and previous mentioned close species, there are 1/512 differences in ITS, 4/ 592 in GAPDH, 8/ 217 in TEF1, 7/970 RPB2 and 13/ 471 in Alt a 1 for A. baoshanensis ; 1/512 differences in ITS, 1/ 592 in GAPDH, 10/ 970 in RPB2, 8/ 471 in Alt a 1 and 12/ 457 in EndoPG for A. koreana ; 49/512 differences in ITS, 4/ 592 in GAPDH and 1/ 471 in Alt a 1 for A. orobanches ; 1/512 differences in ITS, 4/ 592 in GAPDH, 7/ 217 in TEF1, 7/970 RPB2 and 12/ 471 in Alt a 1 for A. ovoidea . Morphologically, A. youyangensis sp. nov. (1–5 conidia per chain) differentiated from its closely related species of A. baoshanensis , A. koreana , A. orobanches , and A. ovoidea (solitary or up to 3 conidia per chain) significantly by its sporulation patterns.

Figures

FIGURE 1. Phylogenetic tree based on the combined gene sequences of ITS, GAPDH, TEF1, RPB2, ALT a 1, EndoPG, and OPA10-2 generated from Alternaria youyangensis sp. nov. on buckwheat. The Bayesian posterior probabilities (PP> 0.60) and maximum likelihood bootstrap values (BS> 60%) are given at the nodes (PP/BS). Examined present strains are in bold.

FIGURE 2. Morphological characteristics of Alternaria youyangensis sp. nov. (YZU 234157).A: Disease symptom; B: Colonies on PDA; C: Sporulation pattern on the PCA; D: Sporulation pattern on the V8A; E–F: Microconidia. Scale bars: C–D = 50 μm, E–F = 25 μm.