Alternaria xinyangensis Lin Huang, Jiao He & D.W. Li, 2024

He, Jiao, Li, De-Wei, Cui, Wen-Li & Huang, Lin, 2024, Seven new species of Alternaria (Pleosporales, Pleosporaceae) associated with Chinese fir, based on morphological and molecular evidence, MycoKeys 101, pp. 1-44 : 1

Alternaria xinyangensis Lin Huang, Jiao He & D.W. Li sp. nov.

Fig. 9

Holotype.

China, Henan Province, Xinyang City, Zhenlei Mountain, 32°04'51"N, 114°07'23"E, isolated from leaf spots of Cunninghamia lanceolata , May 2017, Wen-Li Cui, (holotype: CFCC 59352). Holotype specimen is a living specimen being maintained via lyophilisation at the China Forestry Culture Collection Center (CFCC). Ex-type (ZLS1) is maintained at the Forest Pathology Laboratory, Nanjing Forestry University.

Etymology.

Epithet is after Xinyang City where the type specimen was collected.

Host/distribution.

From C. lanceolata in Zhenlei Mountain, Xinyang City, Henan Province, China.

Description.

Mycelium superficial on the PCA, composed of septate, branched, smooth, thin-walled, white to light brown hyphae. Conidiophores macronematous, mononematous, produced laterally or terminally on the hyphae, cylindrical, erect or ascending, simple or branched, geniculate, pale brown to dark brown, smooth, 1-7 septate, (9.4-)15.3-54.9(-80.4) × (2.9-)3.7-4.8(-5.2) μm, (mean ± SD = 35.1 ± 19.8 × 4.2 ± 0.6 μm, n = 40). Conidiogenous cells apical or subapical, cylindrical, brown, smooth, (3.9-)5.3-9.6(-12.9) × (2.4-)3.3-4.9(-5.5) μm, (mean ± SD = 7.5 ± 2.2 × 4.1 ± 0.8 μm, n = 39), mono- or polytretic, with conspicuous scars after conidia have seceded. Each conidiogenous locus bears a primary chain of 2-7 conidia; each primary chain usually has 1-3 branching chains of 1-3 conidia. Newly-developed conidia subhyaline or pale greyish, ellipsoidal or subacute, thin-walled, 1-3 septate, with few or no protuberance. Mature conidia brown to dark chocolate-brown, spheroidal or ellipsoid to long-ellipsoid, with 1-6 transverse septa and 1-5 longitudinal or oblique septa, (13.8-)19.9-31.8(-37.6) × (6.9-)8.6-12.9(-17.5) μm, (mean ± SD = 25.9 ± 6.0 × 10.7 ± 2.1 μm, n = 37) in size. Secondary conidia commonly produced by means of a short apical or lateral secondary conidiophore, but rarely by conidia through an inconspicuous apical conidiogenous locus. In addition, false beaks (secondary conidiophores), unbranched, short, blunted, pale brown, (3.0-)5.3-16.0(-24.4) × (2.4-)2.8-4.1(-5.1) μm, (mean ± SD = 10.6 ± 5.4 × 3.4 ± 0.7 μm, n = 31). Conidial beakless mostly with a conical cell at the apex. Chlamydospores not observed.

Culture characteristics.

Colonies on PCA incubated at 25 °C in the dark growing at 7.2 mm/d; aerial hyphae cottony, olive green, with white margins; reverse centre black to greyish; sporulation abundant; diffusible pigment absent.

Additional materials examined.

China, Henan Province, Xinyang City, Zhenlei Mountain , 32°04'51"N, 114°07'23"E, isolated from leaf spots of Cunninghamia lanceolata , May 2017, Wen-Li Cui, ZLS1-1, ZLS1-2, ZLS1-3, ZLS1-4 ; China, Henan Province, Xinyang City, Xinyang University , 32°08'20"N, 114°02'06"E, isolated from leaf spots of C. lanceolata , May 2017, Wen-Li Cui, XYXY06, XYXY8-2, XYXY15, XYXY15-1, XYXY15-2, XYXY15-3, XYXY15-4, XYXY16 .

Notes.

The isolates of A. xinyangensis were phylogenetically close to A. dongshanqiaoensis (in this study, DSQ2-2), A. citri (ex-epitype, CBS 107.27), A. cinerariae (ex-epitype, CBS 612.72) and A. kikuchiana (ex-type, CBS 107.53) (Fig. 1 ). Between A. xinyangensis isolates and A. dongshanqiaoensis DSQ2-2, there were 1/453 differences in Alt a1, 1/510 in ITS, 8/664 in OPA10-2, 1/401 in endoPG, 1/757 in RPB2, 1/996 in SSU and 3/293 in TEF1. Between A. xinyangensis isolates and A. citri (ex-epitype, CBS 107.27), there were 1/453 differences in Alt a1, 3/510 in ITS, 8/664 in OPA10-2, 1/401 in endoPG, 1/996 in SSU and 3/293 in TEF1. Between A. xinyangensis isolates and A. cinerariae (ex-epitype, CBS 612.72), there were 1/453 differences in Alt a1, 3/510 in ITS, 8/664 in OPA10-2, 1/401 in endoPG, 1/996 in SSU and 3/293 in TEF1. Between A. xinyangensis isolates and A. kikuchiana (ex-type, CBS 107.53), there were 3/453 differences in Alt a1, 3/510 in ITS, 2/401 in endoPG, 1/757 in RPB2, 1/996 in SSU and 3/293 in TEF1. The PHI analysis showed that there was no significant recombination between A. xinyangensis isolates and their related species (Φw = 0.1647) (Fig. 2A ). Distinguishing characteristics of this new species and other similar species of Alternaria spp. are shown in Table 2 . Morphologically, conidial number in chains of the A. xinyangensis isolates were less than those of A. dongshanqiaoensis DSQ2-2 (2-7 conidia vs. 5-9 conidia). Conidia of the A. xinyangensis isolates were smaller than those of A. citri CBS 107.27 (ex-epitype) (19.9-31.8 × 8.6-12.9 μm vs. 25-40 × 15-25 μm) ( Pierce 1902). Secondary conidiophores of the A. xinyangensis isolates were significantly shorter than those of A. cinerariae CBS 612.72 (ex-epitype) (5.3-16.0 × 2.8-4.1 μm vs. 80-159 × 5-9 μm) ( Nishikawa and Nakashima 2020). Conidia in chains of the A. xinyangensis isolates were less than those of A. kikuchiana CBS 107.53 (ex-type) (2-7 conidia vs. 6-9 conidia) ( Nishikawa and Nakashima 2019). In conclusion, the phylogenetic and morphological evidence supports this fungus as being a new species within the Alternaria alternata species complex.

Figures

Figure 1. Phylogenetic relationships of 116 isolates of the Alternaria species complex with related taxa with concatenated sequences of the SSU, LSU, ITS, GAPDH, RPB 2, TEF 1, Alt a 1, endoPG and OPA 10 - 2 loci using Bayesian inference (BI) and Maximum-likelihood (ML) methods. Bootstrap support values from ML ≥ 70 % and BI posterior values ≥ 0.9 are shown at nodes (ML / BI). Alternaria alternantherae CBS 124392 was the outgroup. * and red font indicates strains of this study. T indicates the ex-type strains, ET indicates the ex-epitype strains, HT indicates the ex-holotype strains.

Figure 2. Splitgraphs showing the results of the pairwise homoplasy index (PHI) test of newly described taxa and closely-related species using both LogDet transformation and splits decomposition A the PHI of Alternaria xinyangensis sp. nov. and A. dongshanqiaoensis sp. nov. with their phylogenetically related isolates or species B the PHI of A. shandongensis sp. nov., A. kunyuensis sp. nov., A. hunanensis sp. nov. and A. longqiaoensis sp. nov. with their phylogenetically related isolates or species C the PHI of A. cunninghamiicola sp. nov. with their phylogenetically-related isolates or species. PHI test value (Φw) <0.05 indicate significant recombination within a dataset. * indicates strains of this study. T indicates the ex-type strains, ET indicates the ex-epitype strains, HT indicates the ex-holotype strains.

Figure 9. Alternaria xinyangensis (ZLS 1) A colony on PCA after 6 days at 25 ° C in the dark B, C sporulation patterns D conidiophores and conidiogenouse cells E conidium. Scale bars: 50 μm (B, C); 10 μm (D, E).