Tubeufiales » Tubeufiaceae » Neohelicosporium

Neohelicosporium ellipsoideum

Neohelicosporium ellipsoideum Y.Z. Lu, J.C. Kang & K.D. Hyde

Index Fungorum number: IF 554870; Facesoffungi number: FoF 04738

Holotype: MFLU 17–1180

Etymology: “ellipsoideum” referring to the ovoid ascomata of this fungus.

 

Saprobic on decaying wood in a freshwater stream. Sexual morph: Ascomata 200–320 μm high × 150–290 μm diam., superficial, seated on a subiculum, solitary, scattered, ellipsoidal to subglobose, upper part pale brown, under part dark brown, coriaceous, with a central ostiole. Ostiole single, central. Peridium 25–35 μm wide, composed of cells of textura angularis, brown. Hamathecium comprising numerous, filiform, septate, branched pseudoparaphyses. Asci 110–140 × 15–18 μm (x̄ = 125 × 16 μm, n = 20), 8-spored, bitunicate, cylindrical, pedicellate, apically rounded. Ascospores 50–65 × 5–7 μm (x̄ = 58 × 6 μm, n = 20), 2–3-seriate, fusiform, tapering towards rounded ends, slightly curved, guttulate, 7–9-septate, hyaline, smooth-walled. Asexual morph: Hyphomycetous, helicosporous. Conidiophores macronematous, mononematous, cylindrical, branched or unbranched, septate, 50–230 μm long, 5–6 μm wide, brown, smooth-walled. Conidiogenous cells holoblastic, mono- to polyblastic, integrated, sympodial, terminal or intercalary, cylindrical, with denticles, 15–25 μm long, 5–6 μm wide, pale brown, smooth-walled. Conidia solitary, acropleurogenous, helicoid, rounded at tip, 20–30 μm diam. and conidial filament 5.5–7 μm wide in the broadest part (x̄ = 25 × 6 μm, n = 20), tapering to 3–4 μm wide at apex and base, 85–115 μm long, tightly coiled 2–2½ times, not becoming loose in water, 14–15-septate, guttulate, hyaline, smooth-walled. (Description from Lu et al. 2018)

 

Culture characteristics: Ascospores germinating on water agar and germ tubes produced from ascospores within 12 h. Colonies growing on MEA, circular, with slightly umbonate surface, edge entire, reaching 11 mm in 2 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, Krabi, Plai Praya, Khao To, Ban Bang Thao Mae, on decaying wood in flowing freshwater stream, 17 December 2015, Saranyaphat Boonmee, BTM01–4 (MFLU 17–1180, holotype; HKAS 100757, isotype), living culture, MFLUCC 16–0229.

 

Notes: Neohelicosporium ellipsoideum is the second sexual morph in the genus Neohelicosporium. Neohelicosporium ellipsoideum is distinct from N. fusisporum by its shorter ascomata (200–320 μm vs. 340–400 μm), wider asci (15–18 μm vs. 9–12 μm) and wider ascospores (5–7 μm vs. 1.6–4.6 μm). The asexual morph of N. ellipsoideum was found from the culture obtained from sexual morph by single spore isolation. The most similar asexual morph species to this taxon in the genus Neohelicosporium is N. aquaticum. Both of them have wide conidial filament and conidia do not become loose in water. However, N. ellipsoideum differs from N. aquaticum by its wider (5.5–7 μm vs. 4–5.5 μm) and shorter (85–115 μm vs. 150–185 μm) conidial filaments. Phylogenetically, Neohelicosporium ellipsoideum is sister to N. acrogenisporum with good bootstrap support. We compared their nucleotides and noted that there are 9, 2, 23 and 16 noticeable nucleotide differences in ITS, LSU, RPB2 and TEF1α sequence data respectively between N. ellipsoideum (MFLUCC 16–0229) and N. acrogenisporum (MFLUCC 17–2019), which indicates that they are distinct species. Therefore, based on both morphological and phylogenetic evidence, N. ellipsoideum is identified as a new species of Neohelicosporium. (Notes from Luo et al. 2018)

 

Freshwater distribution: Thailand (Lu et al. 2018)

 

Fig 1 The sexual morph of Neohelicosporium ellipsoideum (MFLU 17–1180, holotype). a Superficial ascomata on substrate. b Ascoma. c Peridium. d Ostiole. e Subiculum. f Hamathecium. g–k Asci. l–r Ascospores. Scale bars: a = 200 µm, b = 100 µm, c, e, f, l–r = 20 µm, d, g–k = 50 µm (Lu et al. 2018)

 

Fig 2 The asexual morph of Neohelicosporium ellipsoideum (from asexual morph’s cultures). a, b Colonies on MEA from above and below. c–f Conidiogenous cell with attached conidia. g–i Conidiogenous cells. j–l Conidia. Scale bars: c–g, j–l = 20 µm, h, i = 10 µm (Lu et al. 2018)

 

References

Lu YZ, Liu JK (Jack), Hyde KD, Jeewon R, Kang JC, Fan C, Boonmee S, Bhat DJ, Luo ZL, Lin CG, Eungwanichayapant PD (2018) A taxonomic reassessment of Tubeufiales based on multi-locus phylogeny and morphology. Fungal Divers 92:131–344. https://doi.org/10.1007/s13225-018-0411-y

 

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