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

Fig. 7

Holotype.

China, Hunan Province, Yiyang City, Longqiao Town, 28°27'24"N, 112°29'7"E, isolated from leaf spots of Cunninghamia lanceolata , May 2017, Wen-Li Cui, (holotype: CFCC 59357). Holotype specimen is a living specimen being maintained via lyophilisation at the China Forestry Culture Collection Center (CFCC). Ex-type (HN43-14) is maintained at the Forest Pathology Laboratory, Nanjing Forestry University.

Etymology.

Epithet is after Longqiao Town, Yiyang City, Hunan Province where the type specimen was collected.

Host/distribution.

from C. lanceolata in Longqiao Town, Yiyang City, Hunan Province, China.

Description.

Mycelium superficial on the PCA medium, composed of septate, branched, smooth, thin-walled, pale brown to brown hyphae. Conidiophores macronematous, mononematous, solitary, subcylindrical, unbranched or barely branched, straight or geniculate, 2-4 septa, (4.7-) 19.6-51.0 (-66.3) × (2.9-)3.3-4.2(-4.8) μm, (mean ± SD = 35.3 ± 15.7 × 3.8 ± 0.5 μm, n = 39). Each conidiogenous locus bears a primary chain of 4-8 conidia; each chain usually has 1-3 secondary chains of 3-4 conidia. Conidiogenous cells apical or subapical, cylindrical, light brown, smooth, (2.8-)4.3-9.6(-17.4) × (2.3-)2.9-4.5(-5.8) μm, (mean ± SD = 7.0 ± 2.7 × 3.7 ± 0.8 μm, n = 45), mono- or polytretic. Conidia pale brown to brown, ovoid or ellipsoid to long-ellipsoid, pyriform, smooth or verruculose. Conidial bodies (11.0-)16.0-28.2(-40.2) × (6.1-)7.0-12.6(-20.8) μm, (mean ± SD = 22.1 ± 6.1 × 9.8 ± 2.8 μm, n = 48), with 1-5 transverse and 0-2 longitudinal septate. Secondary conidia commonly produced via a short lateral secondary conidiophore, but rarely by conidia through an inconspicuous apical conidiogenous locus. Apically or laterally formed secondary conidiophores (false beaks) with one or several conidiogenous loci, short, mostly single-celled, (3.5-)3.3-11.6(-19.7) × (2.8-)2.9-3.9(-4.8) μm, (mean ± SD = 7.5 ± 4.2 × 3.4 ± 0.5 μm, n = 33). 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 8.3 ± 0.4 mm/d; aerial hypha cottony, dark green to black, with pale green margins; reverse centre black with pale grey margins; sporulation abundant; diffusible pigment absent.

Additional materials examined.

China, Hunan Province, Yiyang City, Longqiao Town , 28°27'24"N, 112°29'7"E, isolated from leaf spots of Cunninghamia lanceolata , May 2017, Wen-Li Cui, HN 43-14-1, HN43-14-2, HN43-14-3 .

Notes.

The isolates of A. longqiaoensis were phylogenetically close to A. vaccinii (ex-type, CBS 118818), A. platycodonis (ex-type, CBS 121348), A. rhadina (ex-type, CBS 595.93), A. citriarbusti (ex-type, CBS 102598) and A. tomaticola (ex-type, CBS 118814) (Fig. 2 ). Between A. longqiaoensis isolates and A. vaccinii CBS 118818 (ex-type), there were 4/453 differences in Alt a1, 2/499 in GAPDH, 4/510 in ITS, 1/401 in endoPG, 2/757 in RPB2 and 18/996 in SSU. Between A. longqiaoensis isolates and ex-type of A. platycodonis CBS 121348, there were 1/453 differences in Alt a1, 2/499 in GAPDH, 4/510 in ITS, 2/757 in RPB2 and 18/996 in SSU. Between A. longqiaoensis isolates and A. rhadina CBS 595.93 (ex-type), there were 1/453 differences in Alt a1, 2/499 in GAPDH, 4/510 in ITS, 2/757 in RPB2 and 18/996 in SSU. Between A. longqiaoensis isolates and A. citriarbusti CBS 102598 (ex-type), there were 1/453 differences in Alt a1, 4/510 in ITS, 2/757 in RPB2 and 18/996 in SSU. Between A. longqiaoensis isolates and A. tomaticola CBS 118814 (ex-type), there were 3/453 differences in Alt a1, 4/510 in ITS, 2/757 in RPB2 and 18/996 in SSU. The PHI analysis showed that there was no significant recombination between A. longqiaoensis isolates and its related species (Φw = 0.3502) (Fig. 2B ). Distinguishing characteristics of this new species and other morphologically-related species of Alternaria spp. are shown in Table 2 . Morphologically, conidia in chains of the A. longqiaoensis isolates were less than those of A. vaccinii CBS 118818 (ex-type) (4-8 conidia vs. 8-10 conidia) ( Simmons 2007), A. platycodonis CBS 121348 (ex-type) (4-8 conidia vs. 8-10 conidia) ( Zhang 2003) A. rhadina CBS 595.93 (ex-type) (4-8 conidia vs. 9-15 conidia) ( Simmons 1993) and A. tomaticola CBS 118814 (ex-type) (4-8 conidia vs. 10-15 conidia) ( Simmons 2007). Transverse septa of conidia of the A. longqiaoensis isolates were less than those of A. citriarbusti CBS 102598 (ex-type) (1-5 vs. 6-11 transverse septa) ( Simmons 1999). Thus, the phylogenetic and morphological evidence supports this fungus as being a new species within the Alternaria alternata species complex.

Figures

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 7. Alternaria longqiaoensis (HN 43 - 14) A colony on PCA after 6 days at 25 ° C in the dark B, C sporulation patterns D, E conidiophore and conidiogenous cells F conidium. Scale bars: 50 μm (B, C); 10 μm (D-F).