Tubeufia laxispora Y.Z. Lu, Boonmee & K.D. Hyde
Index Fungorum number: IF 818987; Facesoffungi number: FoF 02694
Etymology: ‘laxispora’ referring to loosely coiled helicospores.
Holotype: MFLU 16-2663
Saprobic on submerged wood in a stream. Mycelium partly immersed, partly superficial, pale brown, septate, sparsely branched hyphae, with masses of crowded conidia. Sexual morph: Undetermined. Asexual morph: Conidiophores 30.5–73 μm long, 3.5–5 μm wide, pale brown at the base, gradually paler upwards, becoming hyaline, macronematous, erect, short, smooth-walled. Conidiogenous cells monoblastic, holoblastic, integrated, each with single conidium. Conidia 17.5–40 μm diam. and conidial filament 2–4 μm wide (x̄ = 26.5 × 3 μm, n = 20), with 111–182 μm long, loosely coiled 1–3.5 times, rounded at the apical end, multi-septate, slightly constricted at septa, hyaline, smooth-walled. (Lu et al. 2017)
Culture characteristics: Conidia germinating on water agar (WA) within 12 h and germ tubes produced from conidia. Colonies growing on malt extract agar (MEA), circular, edge entire, reaching 12 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-walled.
Materials examined: THAILAND, Krabi, Plai Praya, Khao To, Ban Bang Thao Mae, on decaying wood in a freshwater stream, 17 December 2015, Saranyaphat Boonmee, BTM06-1 (MFLU 16-2663, holotype; GZAAS 16-0145, isotype); ex-type living culture, MFLUCC 16-0232 = GZCC 16-0108; Krabi, Muang, Nongtalay, Khao Hang Nak, on decaying wood in a freshwater stream, 16 December 2015, Saranyaphat Boonmee, HN02-2 (MFLU 16-2662; GZAAS 16-0144); living culture, MFLUCC 16-0219 = GZCC 16-0107.
Notes: Tubeufia laxispora formed an asexual morph on the natural substrate and is morphologically similar to T. tectonae and T. hyalospora. Their colonies on natural substrates are hyaline to white and conidiophores are pale brown at the base; however, these taxa differ in conidia size. The conidia (17.5–40 μm diam.) of T. laxispora are distinctly smaller than T. tectonae (32–55 μm diam.), slightly larger than T. hyalospora (16–33 μm diam.), but the conidial filament is similar in size. Furthermore, T. laxispora shares similar characters to Helicomyces denticulatus in the conidia shape and size. However, the conidiophores of H. denticulatus (5–13 × 3–4.5 μm) are distinctly shorter than T. laxispora (30.5–73 × 3.5–5 μm) and the conidia of H. denticulatus coiled 3.5–3.75 times (Zhao et al. 2007) differs from T. laxispora (conidia coiled 1–3.5 times). Phylogenetically, T. laxispora formed a single clade with high support (91% BS, 1.00 PP) within Tubeufia. Therefore, we introduced it as a novel species. (Lu et al. 2017)
Freshwater distribution: Thailand (Lu et al. 2017, 2018)