Neohelicosporium acrogenisporum Y.Z. Lu, J.C. Kang & K.D. Hyde
Index Fungorum number: IF 554868; Facesoffungi number: FoF 04736
Holotype: MFLU 17–1103
Etymology: “acrogenisporum” referring to acrogenous helicoid conidia of this fungus.
Saprobic on decaying wood in a freshwater stream. Sexual morph: Undetermined. Asexual morph: Hyphomycetous, helicosporous. Colonies on the substratum superficial, effuse, gregarious, white. Mycelium composed of partly immersed, partly superficial, hyaline to pale brown, septate, branched hyphae, with masses of crowded, glistening conidia. Conidiophores macronematous, mononematous, cylindrical, mostly unbranched, occasionally branched, septate, 45–150 μm long, 6–7 μm wide, brown, smooth-walled. Conidiogenous cells holoblastic, mono- to polyblastic, integrated, sympodial, terminal, cylindrical, with denticles, 12–15 μm long, 4–6 μm wide, hyaline to pale brown, smooth-walled. Conidia solitary, acrogenous, helicoid, rounded at tip, 45–60 μm diam. and conidial filament 4.5–7.5 μm wide (x̄ = 52 × 6 μm, n = 20), 345–470 μm long, coiled 2½–3½ times, becoming loosely coiled in water, indistinctly multi-septate, indistinctly multi-septate, guttulate, hyaline, smooth-walled. (Description from Lu et al. 2018)
Culture characteristics: Conidia germinating on water agar and germ tubes produced from conidia within 12 h. Colonies growing on MEA, circular, with flat surface, edge filiform, reaching 15 mm in 4 weeks at 28 °C, brown to dark brown in MEA medium. Mycelium superficial and partially immersed, branched, septate, hyaline to pale brown, smooth.
Material examined: THAILAND, Chiang Rai, Muang, Ban Nang Lae Nai, on submerged decaying wood in a freshwater stream, 31 December 2016, Yong-Zhong Lu, CR20 (MFLU 17–1103, holotype; HKAS 100773, isotype), ex-type living cultures, MFLUCC 17–2019, TBRC 8908.
Notes: Morphologically, Neohelicosporium acrogenisporum is distinct from other Neohelicosporium species by its larger acrogenous conidia and longer conidial filaments. Phylogenetically, N. acrogenisporum shares a sister relationship to N. ellipsoideum with good bootstrap support and support that they are distinct species. (Notes from Lu et al. 2018)
Freshwater distribution: Thailand (Lu et al. 2018)