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

Fig. 3

Holotype.

China, Jiangsu Province, Nanjing City, Dongshanqiao Forest Farm, 31°51'11"N, 118°46'12"E, isolated from leaf spots of Cunninghamia lanceolata , May 2017, Wen-Li Cui, (holotype: CFCC 59358). Holotype specimen is a living specimen being maintained via lyophilisation at the China Forestry Culture Collection Center (CFCC). Ex-type (DSQ3-2) is maintained at the Forest Pathology Laboratory, Nanjing Forestry University.

Etymology.

The specific epithet refers to the genus of the host plant ( Cunninghamia lanceolata ).

Host/distribution.

From C. lanceolata in Dongshanqiao Forest Farm, Nanjing City, Jiangsu Province, China.

Description.

Mycelium superficial on the PCA, composed of septate, branched, smooth, thin-walled, pale white to grey hyphae. Conidiophores macronematous, mononematous, solitary, subcylindrical, branched or unbranched, straight or geniculate, thin-walled, 2-10 septate, (18.3-)25.3-68.4(-93.8) × (3.0-)3.3-4.2(-4.8) μm, (mean ± SD = 46.9 ± 21.6 × 3.7 ± 0.5 μm, n = 32), arising mostly at right angles from undifferentiated hyphae, with conspicuous scars after conidia have seceded. Conidiogenous cells apical or subapical, cylindrical, light brown, smooth, (5.2-)7.3-14.0(-18.1) × (2.5-)3.0-4.2(-5.0) μm, (mean ± SD = 10.7 ± 3.3 × 3.6 ± 0.6 μm, n = 45), mono- or polytretic, with conspicuous scars at the loci of sporulating after conidia have seceded. Each conidiogenous locus bears a primary chain of 3-5 conidia with rarely lateral branches or occasionally a sole secondary conidium. Conidia pale brown to brown, shape varied, ovoid or ellipsoid, pyriform or obclavate, usually smooth; conidial bodies (12.2-)18.1-35.4(-51.6) × (7.5-)10.4-15.5(-18.7) μm, (mean ± SD = 26.6 ± 8.6 × 12.9 ± 2.6 μm, n = 53), with 1-5 transverse and 0-2 longitudinal septate. Secondary conidia directly (but rarely) produced by conidia through an inconspicuous apical conidiogenous locus or (commonly) by means of a short apical or lateral secondary conidiophore with 1-2 cells in length. Secondary conidiophores (false beaks) with one or a few conidiogenous loci, (4.5-)5.2-22.5(-32.7) × (2.7-)3.2-4.2(-4.7) μm, (mean ± SD = 13.8 ± 8.7 × 3.7 ± 0.5 μm, n = 31). Beakless conidia 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 9.3 ± 0.1 mm/d; aerial hypha cottony, white to pale grey; reverse centre dark green to black; sporulation sparse; diffusible pigment absent.

Additional materials examined.

China, Jiangsu Province, Nanjing City, Dongshanqiao Forest Farm, 31°51'11"N, 118°46'12"E, isolated from leaf spots of Cunninghamia lanceolata , May 2017, Wen-Li Cui, DSQ3-2-1, DSQ3-2-2, DSQ3-2-3, DSQ3-2-4 .

Notes.

The isolates of A. cunninghamiicola were phylogenetically close to A. broussonetiae (ex-type, CBS 121455), A. yali-inficiens (ex-type, CBS 121547), A. seleniiphila (ex-type, CBS 127671) and A. lini (ex-type, CBS 106.34) (Fig. 2 ). Between A. cunninghamiicola isolates and A. broussonetiae (ex-type, CBS 121455), there were 1/453 differences in Alt a1, 4/510 in ITS and 1/664 in OPA10-2. Between A. cunninghamiicola isolates and A. yali-inficiens (ex-type, CBS 121547), there were 1/453 differences in Alt a1, 2/499 in GAPDH, 3/510 in ITS and 1/401 in endoPG. Between A. cunninghamiicola isolates and A. seleniiphila (ex-type, CBS 127671), there were 1/453 differences in Alt a1, 2/499 in GAPDH, 3/510 in ITS, 1/401 in endoPG and 6/757 in RPB2. Between A. cunninghamiicola isolates and A. lini (ex-type, CBS 106.34), there were 1/453 differences in Alt a1, 2/499 in GAPDH, 4/510 in ITS, 1/887 in LSU, 1/664 in OPA10-2 and 6/757 in RPB2. The PHI analysis showed that there was no significant recombination between A. cunninghamiicola isolates and its related species (Φw = 0.2087) (Fig. 2C ). Distinguishing characteristics of this new species and other related species of Alternaria spp. are shown in Table 2 . Morphologically, conidia in chains of the A. cunninghamiicola isolates were less than those of A. broussonetiae CBS 121455 (ex-type) (3-5 vs. 8-15 conidia) ( Zhang et al. 1999) and A. yali-inficiens CBS 121547 (ex-type) (3-5 vs. 8-18 conidia) ( Roberts 2005). Conidiophores of the A. cunninghamiicola isolates were shorter than those of A. seleniiphila CBS 127671 (ex-type) (25.3-68.4 × 3.3-4.2 μm vs. 80-250 × 4-5 μm) ( Wangeline and Reeves 2007). Conidia of the A. cunninghamiicola isolates were shorter and wider than those of A. lini CBS 106.34 (ex-type) (18.1-35.4 × 10.4-15.5 μm vs. 42-60 × 3-7 μm) ( Dey 1933). Thus, the phylogenetic and morphological evidence support this fungus 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 3. Alternaria cunninghamiicola (DSQ 3 - 2) A colony on PCA after 6 days at 25 ° C in the dark B sporulation patterns C, D conidiophores and conidiogenous cell E, F conidium. Scale bars: 50 μm (B); 10 μm (C-F).