Apiospora hongheensis X. Zhang & Tibpromma, sp. nov.

Index Fungorum number: IF 901411; Mycobank number: MB 901411; Facesoffungi number: FoF 15837; Fig. 1

Etymology – Named after Honghe City in China, where the fungus was first discovered.

Holotype – MHZU 23-0100

Saprobic on dead culms of unidentified branches. Sexual morph: Not observed. Asexual morph: Colonies on natural substrate surface, powdery, dark brown to black, gregarious, dull with conidia readily liberated when disturbed. Conidiophores reduced to conidiogenous cells. Conidiogenous cells 10–30×4–7 µm (x̄=21×5 µm, n=30), cylindrical, hyaline, smooth-walled, unbranched, erect or slightly curved. Conidia 15–25 × 10–15 µm (x̄= 19 × 12.5 µm, n = 40), subglobose to ellipsoidal, hyaline when immature, brown to dark brown when mature, smooth-walled to finely roughened, guttulate, lacking germ-slit.

Culture characteristics – Conidia germinated on PDA within 24 h. Colonies on PDA at 25–28 ℃ after one month, irregular, flat, undulate edge with white to gray at the margin, the center is black, wrinkled in above, the reverse is white in the middle and gray the margin. Sporulation after two months.

Material examined – China, Yunnan Province, Honghe City, on dead culms of an unidentified plant,17 July 2021, HH03 (holotype, MHZU 23-0100); ex-type, ZHKUCC 23-0792=ZHKUCC 23-0793.

GenBank numbers – ZHKUCC 23-0792=ITS: OR936320, LSU: OR936322, tef1-α: PP778354, tub2: PP778365; ZHKUCC 23-0793=ITS: OR936321, LSU: OR936323, tef1-α: PP778355, tub2: PP778366.

Notes – In the present phylogenetic analyses, Apiospora hongheensis (ZHKUCC 23-0792, 23-0793) forms a separate lineage within Apiospora with 86% ML statistical support and is sister to A. malaysiana (CBS 102053) and A. euphorbiae (IMI 285638b). In morphology, A. hongheensis is distinct from A. malaysiana (CBS 102053) and A. euphorbiae (IMI 285638b) by the morphology of colonies, conidiogenous cells, and conidia. Conidiogenous cells of A. malaysiana aggregate in clusters on hyphae, hyaline to pale brown, doliiform to clavate to ampulliform, conidia globose in surface view, lenticular inside view, with pale equatorial slit (Ellis, 1963, 1965; Crous et al. 2013), while conidiogenous cells of A. hongheensis are cylindrical, hyaline, erect, or slightly curved; conidia are subglobose to ellipsoidal and thin-walled. Based on nucleotide comparisons, A. malaysiana is slightly different from A. hongheensis in 70/605 bp (11.67%) of the ITS, 19/831 (2.29%) of the LSU, 12/549 bp (2.19%) of tub2 and 10/393 bp (2.54%) of tef1-α. Based on nucleotide comparisons, A. euphorbiae is slightly different from A. hongheensis in 10/605 bp (1.65%) of the ITS, 12/831 (1.44%) of the LSU, and 13/549 bp (2.37%) of tub2. Additionally, colonies of A. euphorbiae are effused,
and conidiophores are erect or ascending, simple, flexuous, cylindrical, colourless, except for the numerous brown transverse septa, smooth-walled, thick lenticular conidia, while colonies of A. hongheensis are powdery, dark brown to black, gregarious, dull with conidia readily liberated when disturbed, conidiophores reduced to conidiogenous cells, and conidia are subglobose to ellipsoidal, thin-walled.

Figure 1 – Apiospora hongheensis (ZHKU 23–0100, holotype). a–c Appearance of the fungus on dead culms of an unidentified plant. d–e Conidia with conidiophores. f–h Conidiogenous cells bearing conidia. i–k Conidia. l Germinated conidium. m, q Colony on PDA media (m reversed, q forward). n Sporulation on PDA. o Conidia. p Conidiogenous cells and conidia. Scale bars: d, e=40 μm; f–k, p=20 μm; l, o=50 μm