Diplodia acerigena L.W. Li & Jian K. Liu, 2023

Li, Wen-Li, Liang, Rui-Ru, Dissanayake, Asha J. & Liu, Jian-Kui, 2023, Botryosphaerialean fungi associated with woody oil plants cultivated in Sichuan Province, China, MycoKeys 97, pp. 71-116 : 71

Diplodia acerigena L.W. Li & Jian K. Liu sp. nov.

Figs 7 , 8

Etymology.

The epithet ‘‘acerigena’’ refers to the host genus Acer , on which the holotype was collected.

Holotype.

HKAS 125891.

Description.

Saprobic on decaying branches of Acer truncatum . Sexual morph: Ascomata 304.5-321 × 217-260 (x̄ = 313 × 238.5 μm, n = 20), more or less subglobose, solitary or gregarious, semi-immersed, medium brown to dark brown, unilocular, papillate, ostiolate. Ostiole 101-115 μm diam., conical or circular, central, papillate, periphysate. Peridium 23-29 μm wide, composed of 3-5 layers of dark brown cells of textura angularis. Pseudoparaphyses 3.5-5 μm wide, hyaline, branched, septate. Asci 98-120 × 24-32.5 μm (x̄ = 109 × 28 μm, n = 30), (4-)8-spored, clavate, stipitate, irregularly bitunicate, apex rounded with an ocular chamber. Ascospores 24.5-31.5 × 13.5-16 μm (x̄ = 28 × 14.5 μm, n = 30), L/W ratio = 2, biseriate, broadly fusiform to oval, widest in the middle, both ends obtuse, hyaline, moderately thick-walled, smooth, becoming brown and 2-septate when aged. Asexual morph: Coelomycetous, pycnidia produced on mycelium in PDA. Conidiomata stromatic, mostly solitary, gray to black, globose to subglobose. Paraphyses 2-3.5 μm wide, hyaline, subcylindrical, branched, septate. Conidiophores absent. Conidiogenous cells 9-12 × 3.5-5 μm (x̄ = 10.5 × 4.5 μm, n = 20), holoblastic, hyaline, cylindrical. Conidia 21-24 × 10-11 μm (x̄ = 22.5 × 10.5 μm, n = 30), L/W ratio = 2, aseptate, thick-walled, wall externally smooth, roughened on the inner surface, initially hyaline becoming dark brown, obovoid to ellipsoid, both ends broadly rounded. Spermatogenous cells 7-9.5 × 2.5-3.5 μm (x̄ = 8 × 3 μm, n = 20), discrete or integrated, hyaline, smooth, cylindrical, holoblastic or proliferating via. determinate phialides with periclinal thickening. Spermatia 7-11.5 × 3-4 μm (x̄ = 9 × 3.5 μm, n = 30), hyaline, smooth, aseptate, rod-shaped with rounded ends.

Culture characteristics.

Ascospores germinating on PDA within 12 h. Colonies growing on PDA, reaching a diam. of 4 cm after five days at 25 °C, effuse, velvety, with entire to slightly undulate edge. Surface initially white and later turning dark olivaceous from the surrounding of the colony and dark gray in reverse.

Material examined.

China, Sichuan Province, Chengdu City, Pidu District , 30°19'57"N, 103°59'47"E, elevation 442 m, on dead branches of Acer truncatum ( Anacardiaceae ), 19th March 2021, W.L Li, YBF 96 (HKAS 125891, holotype), ex-type living culture UESTCC 22.0073 = CGMCC 3.24157; ibid., YBF103 (HUEST 22.0075, paratype), living culture UESTCC 22.0074. Additional sequences: LSU: OQ164827 (CGMCC 3.24157), OQ164828 (UESTCC 22.0074) .

Notes.

Three isolates of Diplodia acerigena clustered closer to Di. pseudoseriata (CBS 124906) with high bootstrap support (ML/BI 100%/1). The asexual morph of Diplodia pseudoseriata was introduced by Pérez et al. (2010), collected and isolated from the Blepharocalyx salicifolius in Uruguay and its sexual morph has not been reported. The asexual morph of Diplodia acerigena differs from Di. pseudoseriata in having conidia which become 1-septate when aged. Diplodia acerigena shares similar sexual morph characters as of other Diplodia species by having immersed to semi-immersed pseudothecia, clavate asci, broadly fusiform to ovoid and hyaline ascospores. However, conidia of Diplodia acerigena become brown and septate when aged, which is rarely observed in any other sexual morph species of this genus.

Figures

Figure 7. The sexual morph of Diplodia acerigena (HKAS 125891, holotype) a, b appearance of ascomata on natural substrate c vertical section of ascoma d ostiole e section of peridium f-h asci with hyaline ascospores i asci with brown 2 - sepatate ascospores j, k hyaline immature aseptate ascospores l-n mature brown 2 - septate ascospores o germinated ascospore p upper view of the colony on PDA after 14 d q reverse view of the colony on PDA after 14 d. Scale bars: 100 μm (c); 10 μm (d, e, j-o); 20 μm (f-i).

Figure 8. The asexual morph of Diplodia acerigena (HKAS 125891, holotype) a-d appearance of conidiomata on PDA e-i conidiogenous cells and developing conidia j, k hyaline immature conidia l-o mature brown aseptate conidia p-t Spermatogenous cells and Spermatia. Scale bars: 10 μm (e-o, t); 5 μm (p-s).