Neohelicosporium irregulare Y.Z. Lu, J.C. Kang & K.D. Hyde, Fungal Diversity 92: 235 (2018)
Index Fungorum number: IF 554871; MycoBank number: MB 554871; Facesoffungi number: FoF 04739; Figs. 1, 2
Saprobic on submerged decaying wood. Sexual morph Undetermined. Asexual morph Hyphomycetous, helicosporous. Colonies effuse, white, shiny, with crowded by conidial masses. Mycelium composed of superficial and partly immersed, branched, anastomosing, septate, brown hyphae, smooth-walled. Conidiophores 116–229.5×6–8 µm, micronematous, mononematous, arising from repent mycelium, tapering toward narrow at apex, widest at base, branched, septate, brown, smooth-walled. Conidiogenous cells holoblastic, mono- to polyblastic, terminal or intercalary, integrated, subhyaline, bearing lateral minute denticles each with single conidium. Conidia 36–53 µm diam., with conidial filament 3–4.5 µm wide, with 190.5–236 µm long, loosely coiled 1–3 times, becoming loosely uncoiled in water, rounded at apical ends, indistinctly multi-septate, not constricted at the septa, hyaline, with granular contents.
Culture characteristics – Conidium germinating on MEA within 24 h and many germ tubes produced from conidium cells. Colonies growing on MEA, reaching greater than 10 mm diam. in 7 days at room temperature, irregular, slightly raised, with edge undulate to fimbriate, dark brown. Mycelium developing superficial, partly immersed, composed of branched, septate, light brown to dark brown hyphal filaments, conidial spores formed on hyphae in culture at 60 days. Conidia 29–49 µm diam., conidial filament 4–5.5 µm wide, 167–208 µm long, loosely coiled 1–3½ times, becoming loosely uncoiled in water, rounded at apical ends, indistinctly multi-septate, not constricted at the septa, hyaline to brown, with granular contents.
Material examined – THAILAND, Chiang Rai Province, Muang, Mae Yao, Huay Mae Sai, on submerged decaying wood in a small freshwater stream, 17 March 2016, S. Boonmee, HMS03 (MFLU 21-0097), living culture, MFLUCC 16-0721; HMS04 (MFLU 21-0098, new record) living culture, MFLUCC 16-0722; HMS05 (MFLU 21-0099), living culture, MFLUCC 16-0723; HMS17 (MFLU 21-0102), living culture, MFLUCC 16-0758.
GenBank numbers – HMS03 – ITS = MZ538516, LSU = MZ538550, TEF1-α = MZ567093; HMS04: ITS=MZ538517, LSU=MZ538551, TEF1-α=MZ567094; HMS05: ITS = MZ538518, LSU = MZ538552, TEF1-α = MZ567095; HMS17: ITS = MZ538519, LSU=MZ538553, TEF1-α=MZ567096.
Notes – Four new collections of Neohelicosporium irregulare (MFLUCC 16-0721, MFLUCC 16-0722, MFLUCC 16-0722 and MFLUCC 16-0758) were recovered from submerged decaying wood from Chiang Rai Province. They can be identified as Neohelicosporium since they formed typical effuse colonies, erect conidiophores and long filamentous, multi-septate with hyaline to light pigmented helicospores (Figs. 1 and 2). They share a close phylogenetic affinity to the ex-type strain Neohelicosporium irregulare (MFLUCC 17-1796) in the combined LSU, ITS and TEF1-α sequenced data, which confirmed that they are the same species (Fig. 3).
Figure 1 – Neohelicosporium irregulare (MFLU 21-0098, new record). a Colony on decaying wood. b, c Conidiophores with lateral minute polyblastic denticles and attached conidia. d–i Conidia. Scale bars: a=100 µm, b–i=20 µm
Figure 2 – Neohelicosporium irregulare sporulation in culture (MFLUCC 16-0722). a Germinated conidium. b, c Culture on MEA from surface and reverse. d–f Mycelium and development of conidia in culture. g–l Conidia. Scale bars: a, e–l=20 µm, d=100 µm
Figure 3 – 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