Acrogenospora taiwanica Roland Kirschner, Taiwania 70 (1): 125–131 (2025)

Fig. 4

Description.

Saprobic on rotting wood in freshwater. Sexual morph: Undetermined. Asexual morph: Hyphomycetous. Colonies on natural substrate, hairy, sparse, black. Mycelium mostly submerged, 1.5–3 µm wide, composed of hyaline to brown septate hyphae. Conidiophores 92.5–417 × 5–7.5 µm (x ̄ = 235.5 × 6, n = 30), solitary, straight or slightly curved, septate, unbranched, cylindrical, dark brown, paler to the apex, smooth. Conidiogenous cells monoblastic, integrated, initially terminal, later becoming intercalary, cylindrical, smooth, brown. Conidia 21–32.5 µm (x ̄ = 27, n = 50) diam., solitary, terminal or lateral, globose or subglobose, hyaline when young, dark brown when mature, smooth, thick-walled, aseptate, sometimes with a large guttule, base truncate.

Cultural characteristics.

Conidia germinating on PDA within 24 hours and germ tubes produced from the conidial base. Colonies cultivated on PDA exhibited slow growth, attaining a diameter of 23 mm over 24 days at 25 ° C under natural light. The spore exhibited a round and hairy morphology, with a dense aerial mycelium covering the surface. The margins of the regular mycelium appear slightly dispersed, while both the anterior and posterior surfaces are consistently rounded and exhibit a black coloration.

Material examined.

China • Jiangxi Province, Jiujiang City, Yongxiu County, Yunjushan Mountain, 29.23°N, 115.59°E, at an altitude of 672.5 m, on decaying wood submerged in a freshwater stream, 28 April 2020, Z. J. Zhai, YJS- 30 (HFJAU 10105), living culture JAUCC 5524; 4 May 2021, Z. J. Zhai, YJS 66 (HFJAU 10229), living culture JAUCC 5528.

Notes.

Phylogenetic analysis revealed that our new isolates (JAUCC 5524 and JAUCC 5528) clustered together (100 % ML, 1.00 PP; Fig. 1) with Acrogenospora taiwanica (BCRC FU 3153 and TNM 5903). At the ITS locus, the newly isolated strains JAUCC 5524 and JAUCC 5528 showed four and six nucleotide differences (excluding gaps), respectively, compared to the holotype of A. taiwanica TNM 5903, while exhibiting only two and four (excluding gaps) differences relative to A. taiwanica BCRC FU 3153 (Kirschner 2025). Furthermore, our two strains showed no variation in their LSU sequences and were identical to A. taiwanica BCRC FU 3153. Morphologically, our new collections resemble the holotype of A. taiwanica, except for the slightly larger (21–32.5 μm vs. 21.5–25 μm) conidia (Kirschner 2025). The difference in conidial size might be due to factors such as habitat and incubation time (Yang et al. 2018; Zhang et al. 2022). Acrogenospora taiwanica was previously found on dead terrestrial wood from Taiwan Province, China, and our new collections were collected from submerged, decaying wood in Jiangxi Province, which is a new discovery in freshwater habitats in mainland China.