Jennwenomyces guizhouensis D. Xiong & Y.Y. Chen, 2025

Xiong, Dan, Ou, Jing & Chen, Ya-Ya, 2025, Jennwenomyces guizhouensis sp. nov. from a freshwater habitat in Guizhou, China, Phytotaxa 694 (1), pp. 46-56 : 50

Jennwenomyces guizhouensis D. Xiong & Y.Y. Chen , sp. nov. FIGURE 2

Index Fungorum number: IF 903259

Etymology: The specific epithet ‘ guizhouensis ’ refers to the locality “ Guizhou Province ”, from where the holotype was collected.

Holotype: GZAAS 24-0074

Saprobic on decaying wood in a freshwater habitat. Sexual morph Undetermined. Asexual morph: Hyphomycetous. Colonies on natural substrate superficial, effuse, solitary, scattered or gregarious, golden brown, shining. Mycelium mostly immersed (partly superficial), composed of branched, septate, pale brown to brown hyphae. Conidiophores 105–158.5 × 3.5–5.5 μm (x̅ = 129 × 4.5 μm, n = 20), macronematous, mononematous, solitary, unbranched, cylindrical, uneven in width, straight or flexuous, 4–7-septate, pale brown to brown, paler towards the apex, smooth, thick-walled. Conidiogenous cells 17–40 × 3–4.5 μm (x̅ = 30 × 3.7 μm, n = 20), holoblastic, mono- or polyblastic, integrated, terminal, determinate or sometimes with cylindrical, enteroblastic percurrent extension, subcylindrical to cylindrical, pale brown to brown, smooth-walled. Conidia 32.5–51.5 × 7–10.5 μm (x̅ = 40.5 × 8.5 μm, n = 40), acrogenous, solitary, dry, 2–4-euseptate, guttulate, smooth-walled, pale brown to orange brown, with the end cells paler, straight or sometimes slightly bent, navicular or obclavate to cylindro-clavate, obtusely conic or rounded at the apex, obconic at the base.

Culture characteristics: Conidia germinating on PDA within 10 h and germ tubes arising from the terminal end of the conidium. Colonies reached 23 mm diam. after 32 days of incubation at 25 ℃, circular, with flat, grayish white to pale brown mycelium on the surface, reverse brown to black brown with entire margin.

Material examined: China, Guizhou Province, Qiannan Buyei and Miao Autonomous Prefecture , Dushan County, Zilin Mountain National Forest Park , on submerged decaying wood in freshwater habitat, 6 November 2024, Dan Xiong, ZLS8 (GZAAS 24-0074, holotype), ex-type living culture GZCC 24-0171 ; Ibid., ZJS10 (GZAAS 24-0075, paratype), living culture GZCC 24-0172.

Notes: The phylogenetic tree ( Fig. 1 ) showed that the two isolates of Jennwenomyces guizhouensis (GZCC 24- 0171 and GZCC 24-0172) form a highly supported clade, sister to J. navicularis (BCRC FU30873). A comparison of LSU and ITS sequences between J. guizhouensis (GZCC 24-0171) and J. navicularis (BCRC FU30873) reveals their nucleotide differences of 1/741 bp (0.1%, without gap) and 16/494 bp (3.2%, including two gaps), respectively, indicating that they are distinct species. Morphologically, Jennwenomyces guizhouensis can be distinguished from J. navicularis ( Goh & Kuo 2020) by its larger conidiophores (105–158.5 × 3.5–5.5 μm vs. 70–86.5 × 3.5–4.5 μm wide), and broader conidia (7–10.5 μm vs. 5–9 μm) with fewer septa (2–4 vs. 4–6). Moreover, the conidiogenous cells of Jennwenomyces navicularis are annellate at the apex, which are absent in J. guizhouensis ( Goh & Kuo 2020) . Based on these morphological differences and the results of phylogenetic analyses, Jennwenomyces guizhouensis was introduced as a new species.

Figures

FIGURE 1. Phylogenetic tree generated from the RAxML analysis based on the combined dataset of LSU and ITS sequences. The Maximum Likelihood (ML) and Bayesian Inference (BI) analyses yielded similar tree topologies. Bootstrap support values for ML (≥ 75%) and PP (≥ 0.95) are indicated near their respective nodes. The tree is rooted with Diluviicola aquatica (MFLUCC 15-0986) and Pseudoproboscispora thailandensis (MFLUCC 15-0989). Ex-type strains are denoted with “T” and newly obtained isolates are in bold black fonts.

FIGURE 2. Jennwenomyces guizhouensis (GZAAS 24-0074, holotype). a, b Colonies on the natural substrate. c–f Conidiophores and conidiogenous cells. g–j Conidiogenous cells and attachment of conidia. m–p Conidia. q Germinating conidium. k, l Colonies on PDA from above and below. Scale bars: c–f = 40 µm, q = 20 µm, g–j, m–p = 10 µm.