Tubeufiales » Tubeufiaceae » Helicoarctatus

Helicoarctatus thailandicus

Helicoarctatus thailandicus D.F. Bao, Z.L. Luo, K.D. Hyde & H.Y. Su, sp. nov. Index Fungorum number: IF556259; Facesoffungi number: FoF 05831;


Sexual morph: Undetermined. Asexual morph: Colonies on the substratum superficial, effuse, gregarious, velvety, white to pale brown, shiny. Mycelium composed of partly immersed, partly superficial, brown to dark brown, septate, branched hyphae. Conidiophores 302–536 μm long, 6–11 μm wide (x̄ = 415.3 × 9.4 μm, n = 30), macronematous, mononematous, erect, cylindrical, straight or slightly flexuous, unbranched, tapering towards apex, with red to purple appendage near apex, septate, brown to reddish brown, smooth-walled. Conidiogenous cells 3–6.9 μm long, 2.5–4.5 μm wide, holoblastic, monoblastic, determinate, denticulate, arising laterally from lower portion of the conidiophores as tiny tooth-like protrusions, with each bearing 1 tiny sporogenous conidiogenous loci, hyaline, smooth-walled. Conidia 44–62 μm diam, 417–524 μm long, 3.7–6.8 μm wide (x̄= 460 × 51 μm, n = 30), solitary, helicoid, rounded at both of ends, muriform, with small guttule, aseptate, tightly coiled 4 times, becoming loosely coiled in water, hyaline, smooth-walled.

Culture characteristics: Conidia germinating on PDA within 24 h. Colonies on MEA at room temperature reaching 2.3 cm diam in 3 weeks, mycelium pale brown to greyish brown after 3 weeks, composed of brown to dark brown, septate, smooth or verrucose hyphae.

Material examined: THAILAND, Khwaeng Bang Chak, Khet Phra Khanong Krung Thep Maha Nakhon, on submerged decaying wood, October 2017, Z.L. Luo, B site 3–2–1. (MFLU 19–0555, holotype), ex-type culture, MFLUCC 18–0332.

GenBank Accession No: LSU: MK559869; SSU: MK559780;TEF1-α: MK541685.


Notes: In our phylogenetic analyses, Helicoarctatus thailandicus clustered with H. aquaticus but was separate in a distinct lineage with full support (100 ML/1.00 PP). Morphologically, H. thailandicus resembles H.aquaticus in having unbranched, septate, and wide at bottom, tapering at apex conidiophores, holoblastic, determinate, discrete, denticulate, hyaline conidiogenous cells and helicoid, hyaline conidia. However, H. thailandicus differs from H. aquaticus in its conidiophores with a red to purple appendage near the apex and aseptate conidia, rounded at both of ends, and becoming loosely coiled in water. The conidiophores of H. aquaticus are without an appendant and the conidia are not rounded at the tip and do not become loosely coiled in water.