Helicosporium luteosporum Y.Z. Lu, Boonmee & K.D. Hyde, 2017

Lu, Yong-Zhong, Boonmee, Saranyaphat, Bhat, D. Jayarama, Hyde, Kevin D. & Kang, Ji-Chuan, 2017, Helicosporium luteosporum sp. nov. and Acanthohelicospora aurea (Tubeufiaceae, Tubeufiales) from terrestrial habitats, Phytotaxa 319 (3), pp. 241-253 : 248-250

Helicosporium luteosporum Y.Z. Lu, Boonmee & K.D. Hyde , sp. nov. FIGURES 4–5

Index Fungorum number: IF 552663; Facesoffungi number: FoF 02763

Etymology: ‘ luteosporum ’ referring to yellow colonies with masses of helicospores in natural woody substrate.

Saprobic on decaying wood, in terrestrial habitat. Colonies effuse, yellow, with masses of crowded conidia in natural habitat. Asexual morph: helicosporous hyphomycetes. Conidiophores 68–103 (–135) μm long × 2.5–4.0 μm wide (x = 87 × 3.5 μm, n = 20), macronematous, mononematous, erect, straight or slightly flexuous, septate, unbranched, tapering toward narrow subacute apex, brown, smooth-walled, arising directly on substrate. Conidiogenous cells holoblastic, monoblastic to polyblastic, each with tooth-like protuberance. Conidia 17–24.5 μm diam., with conidial filament 1.5–2.5 μm wide (x = 20 × 2 μm, n = 50), loosely coiled 1½–3 times, becoming loosely uncoiled in water, rounded at apical ends, multi-septate, guttulate, hyaline, becoming yellowish brown when aged, smooth-walled. Sexual morph: not observed.

Culture characteristics:— Conidia germinating in water agar (WA) within 24 h and germ tubes produced from conidium cells. Colonies growing slowly on malt extract agar (MEA), irregular, with rough surface, with undulate edge, reaching 10 mm in 2 weeks at 28 °C, initially brown and becoming dark brown when aged. Mycelium superficial and partly immersed, branched, septate, pale brown to brown, smooth-walled. Asexual sporulation on MEA, with erect, septate, brown conidiophores and helicosporous conidia occurring on tooth-like protuberant conidiogenous cells ( FIG. 5 ).

Material examined:— THAILAND, Krabi, Watthumsua, on decaying wood in terrestrial habitat on a mountain, 15 December 2015, Saowaluck Tibpromma , KST02 ( MFLU 16–2871 , holotype; GZAAS 16–0152 , isotype) ; ex-type living culture, MFLUCC 16–0226 , GZCC 16–0115 .

Notes:— Helicosporium is characterized by macronematous conidiophores, with intercalary, lateral, minute, denticulate conidiogenous cells and tightly to loosely coiled, multi-septate, holoblastic conidia. Morphologically, H. luteosporum shares common characters with H. murinum and the representative type species, H. vegetum ( Zhao et al. 2007, Boonmee et al. 2014), but it is distinct from these species in having different sized conidiophores and conidia. The conidiophores of H. luteosporum is shorter than those of H. vegetum (68–103 μm vs. 107–220 μm) and conidia diameter (17–24.5 μm diam.) is larger than H. murinum (10–15 μm diam.) and H. vegetum (10–15 μm diam.). Moreover, the conidia of H. luteosporum will become yellow colored when matured while other two will not. Phylogenetically H. luteosporum formed a distinct clade from H. vegetum which also indicate this taxon is a new species.

Figures

FIGURE 4. Helicosporium luteosporum (MFLU 16–2871, holotype). a Conidia arising directly from hyphal cells on natural substrate. b–d Conidiophores with conidia. e Conidiophores with conidiogenous cells. f–j Conidium. Scale bars: a = 200 μm, b–c = 50 μm, d–j = 10 μm.

FIGURE 5. Helicosporium luteosporum. Colonies on MEA. a Germinating conidium. b–c Colonies on MEA from above and below. d Conidia growing on MEA at sex months. e–f Conidiophores with conidia. g–h Conidiophores and conidiogenous cells. i–m Conidium. Scale bars: a, e–g = 20 μm, b–c = 20 mm, d = 100 μm, h–m = 10 μm.