Tubeufia krabiensis Y.Z. Lu, Boonmee & K.D. Hyde
Index Fungorum number: IF 554905; Facesoffungi number: FoF 04760
Etymology: “krabiensis” referring to collecting site.
Holotype: MFLU 17–1174
Saprobic on decaying wood in a freshwater stream. Sexual morph Undetermined. Asexual morph Hyphomycetous, helicosporous. Colonies on the substratum superficial, effuse, gregarious, white. Mycelium composed of partly immersed, partly superficial, hyaline to pale brown, septate, branched hyphae, with masses of crowded, glistening conidia. Conidiophores macronematous, mononematous, cylindrical, branched, septate, 35–116 μm long, 5–6.5 μm wide, the lower part brown and the upper part hyaline to pale brown, smooth-walled. Conidiogenous cells holoblastic, mono- to polyblastic, integrated, sympodial, terminal, cylindrical, repeatedly geniculate, truncate at apex after conidial secession, 8.5–21 μm long, 4–5.5 μm wide, hyaline to pale brown, smooth-walled. Conidia solitary, acropleurogenous, helicoid, rounded at tip, 35–45 μm diam. and conidial filament 5.5–8 μm wide (x¯ = 39 × 6.5 μm, n = 20), 180–260 μm long, tightly coiled 2½–3¾ times, not becoming loose in water, 27–28-septate, guttulate, hyaline. (Lu et al. 2018)
Culture characteristics: Conidia germinating on water agar and germ tubes produced from conidia within 12 h. Colonies growing on MEA, circular, with flat surface, edge entire, reaching 28 mm in 3 weeks at 28 °C, pale brown to 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, BTM01–3 (MFLU 17–1174, holotype; HKAS 100756, isotype), ex-type living culture, MFLUCC 16–0228.
Notes: Tubeufia krabiensis is morphologically similar to T. sympodiophora and T. mackenziei in conidia characters but can be distinguished by conidiophore and conidial size. Tubeufia krabiensis differs from T. sympodiophora and T. mackenziei by its conidiogenous cells which appear on the end cells of conidiophores. Besides, the conidiogenous cells of T. mackenziei have characteristic denticulate protrusions while T. krabiensis is repeatedly geniculate and truncate at apex after conidial secession. Furthermore, the conidiophores of T. krabiensis are shorter but wider than T. sympodiophora (35–116 × 5–6.5 μm vs. 120–300 × 4–5 μm). The conidia of T. krabiensis (35–45 μm) are larger than T. sympodiophora (22–33 μm) and T. mackenziei (26.5–32.5 μm) (Matsushima 1993; Lu et al. 2017). Phylogenetically, T. krabiensis shares a sister relationship to T. hyalospora with high bootstrap support (Lu et al. 2018). Tubeufia krabiensis differs from T. hyalospora in features of conidiophores and conidiogenous cells as well as conidia (Hyde et al. 2016). The conidiogenous cells of T. krabiensis are repeatedly geniculate and truncate at apex after conidial secession in the end cells of conidiophores, while T. hyalospora has denticulate protrusions along the whole conidiophores. The conidia of T. krabiensis are larger than T. hyalospora (35–45 × 5.5–8 μm vs. 16–33 × 3–5 μm). (Lu et al. 2018)
Freshwater distribution: Thailand (Lu et al. 2018)