Neohelicosporium parvisporum Y.Z. Lu, J.C. Kang & K.D. Hyde, Mycol. Progr. 17(5): 637 (2017)

Index Fungorum number: IF 822056; MycoBank number: MB 822056; Facesoffungi number: FoF 03571; Fig. 1

Saprobic on submerged decaying wood. Sexual morph Undetermined. Asexual morph Hyphomycetous, helicosporous. Colonies on the substrate superficial, effuse, gregarious, white to light pink. Mycelium composed of partly immersed, partly superficial, hyaline to pale brown, septate, abundantly branched hyphae, with masses of crowded, glistening conidia. Conidiophores up to 400 μm long, 4–6 μm wide, micronematous, mononematous, flexuous, cylindrical, branched, septate, pale brown, smooth-walled. Conidiogenous cells 8–12 μm long, 2.5–5 μm wide, holoblastic, monoto polyblastic, integrated, intercalary, cylindrical, with denticles, pale brown, smooth-walled. Conidia 13.5–33 μm diam., conidial filament 2–4 μm wide, 100–150 μm long, tightly coiled 3–4 times, becoming loosely coiled in water, rounded at the tip, multi-septate, verrucose, guttulate, hyaline.

Culture characteristics – Conidia germinating on MEA and producing germ tubes within 12 h. Colonies growing on PDA, circular, umbonate, surface rough and wrinkled, edge entire, reaching 10–15 mm in 2 weeks at 25 °C, pale brown to brown, mycelium superficial and partially immersed, branched, septate, hyaline to pale brown, smooth.

Material examined – THAILAND, Chiang Mai Province, Mushroom Research Center, on submerged decaying wood in a freshwater stream, 29 January 2019, S. Boonmee, SB18-3 (MFLU 21-0123, new record), living culture, MFLUCC 21-0107.

GenBank numbers – ITS=MT864353, LSU=MT860431.

Notes – Neohelicosporium parvisporum was introduced by Lu et al. (2018a), which was collected from a freshwater habitat. Based on phylogenetic analysis of combined ITS, LSU and TEF1-α sequence data showed that our isolate (MFLUCC 21-0107) clusters among isolates N. parvisporum without statistical support (Fig. 2). Our isolate has similar conidial and conidiophore morphology to N. parvisporum (MFLUCC 17-1523). However, our isolate has smaller conidiogenous cells (8–12×2.5–5 vs. 14.5–22.5×3.5–4.5 μm) and larger conidia (13.5–33×14–24.5 μm) (Fig. 1). A comparison of the ITS nucleotides of N. parvisporum (MFLUCC 17-1523= GZCC 16-0088) and the new strain (MFLUCC 21-0107) revealed 9/550 (1.64%) nucleotide differences.

Figure 1 –  Neohelicosporium parvisporum (MFLU 21-0123, new record). a Substrate. b, c Colony on decaying wood. d–f Conidiophores with conidia. g–i Conidiogenous cells. j–m Conidia. Scale bars: a=20 mm, b, c=500 μm, d=100 μm; e–m=20 μm

Figure 2 – Maximum likelihood phylogenetic tree based on a combined ITS, LSU and TEF1-α sequence data of Neohelicosporium taxa and related genera in Tubeufiaceae. Forty-five taxa are included in the combined analyses which comprise a total of 2348 characters. Neochlamydotubeufia fusiformis (MFLUCC 16-0016) is selected as the outgroup taxon. The best RAxML tree with a final likelihood value of − 5971.586719 is presented. RAxML analysis yielded 343 distinct alignment patterns and 12.46% of undetermined characters or gaps. Estimated base frequencies were as follows: A=0.230669, C=0.271979, G=0.266714, T=0.230637, with substitution rates AC=0.718733, AG=2.140841, AT=1.942223, CG=0.669931, CT=13.341832, GT=1.000000; gamma distribution shape parameter alpha=0.020000. Bootstrap support values for maximum likelihood (MLBS, left) equal to or greater than 70% is given above the nodes. Bayesian posterior probabilities (BYPP, right) equal to or greater than 0.95 are given above the nodes. Ex-type strains are in bold and newly generated sequences are in blue