Neohelicomyces brevis L. J. Zhang, Y. Z. Lu & X. J. Xiao sp. nov.
Fig. 3
Etymology.
Referring to the short conidiophores of holotype.
Holotype.
GZAAS 25-07822.
Description.
Saprobic on decaying wood in a freshwater habitat. Sexual morph: Undetermined. Asexual morph: Hyphomycetous, helicosporous. Colonies on natural substrate superficial, white, gregarious, glistening. Mycelium partly superficial, partly immersed, branched, aseptate, smooth, pale brown to brown, glistening conidia. Conidiophores, micronematous. Conidiogenous cells 6–12 × 2–5 µm (x ̄ = 10 × 3.5 μm, n = 20), holoblastic, monoblastic or polyblastic, integrated, cylindrical, smooth-walled, hyaline, denticulate, truncate at apex after conidial secession. Conidia 113–186 × 2–4 µm (x ̄ = 145 × 3 μm, n = 30), helicoid, solitary, rounded at tip, 18–26 μm diam, tightly coiled 2 1 / 2–3 1 / 3 times, becoming loosely coiled in water, indistinctly multiseptate, guttulate, smooth-walled, hyaline.
Cultural characteristics.
Conidia germinated on PDA within 12 h, and germ tube produced from conidia. Colonies on PDA medium reaching to 35 mm diam. after 70 days at 25 ° C under natural light, dry, dense, with irregular shape, raised surface, and filamentous margin. The outermost mycelium was immersed in the medium, brown to pale brown. The reverse is pale brown to dark brown, becoming paler near the center. No diffusible pigment was observed.
Material examined.
China • Qiannan Buyei and Miao Autonomous Prefecture, Libo County, Guizhou Maolan National Nature Reserve, 25°17'6"N, 108°4'27"E, altitude 470 m, on submerged decaying wood in a stream, 31 May 2025, Xingjuan Xiao, QLS 2 (GZAAS 25-07822, holotype), ex-type culture GZCC 25-27621; ibid. QLS 2 b (GZAAS 25-07823, isotype), ex-isotype culture, GZCC 25-27622.
Notes.
Phylogenetically, the two new strains GZCC 25-27621 and GZCC 25-27622 clustered into a distinct monophyletic clade, forming a sister clade to Neohelicomyces qixingyaensis (CGMCC 3.25569), with support values of 95 % ML / 0.97 BYPP (Fig. 1). Pairwise nucleotide comparisons revealed that N. brevis (GZCC 25-27621, ex-type) and N. qixingyaensis (CGMCC 3.25569, ex-type) shared 402 / 424 bp (95 %) similarity in the ITS region, 787 / 788 bp (99 %) in the LSU region, 915 / 948 bp (97 %) in the rpb 2 region, and 853 / 855 bp (98 %) in the LSU 1 - α region, excluding gaps. Morphologically, N. qixingyaensis (HKAS 128928, holotype) possesses developed macronematous, mononematous conidiophores (94.5–187 × 3.5–6 μm), monoblastic or polyblastic, integrated conidiogenous cells with denticles (7–18 × 3–5.5 μm), and helicoid, aseptate conidia that do not become loose in water (98–147 μm × 1.5–3 μm) (Ma et al. 2024 b). In contrast, our new isolate has micronematous conidiophores and produces conidia that become loosely coiled in water, are septate, and are longer than N. qixingyaensis (113–186 × 2–4 µm vs. 98–147 μm × 1.5–3 μm) (Ma et al. 2024 b). The two species differ ecologically, with N. brevis being saprobic in freshwater habitats, whereas N. qixingyaensis occurs in terrestrial habitats (Ma et al. 2024 b). Based on both molecular and morphological evidence, the new species Neohelicomyces brevis is herein proposed.
Publication Date: 2026-06-17