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

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.