Tubeufia longihelicospora Boonmee, Promputtha & K.D. Hyde, sp. nov.

Index Fungorum number: IF 558543; MycoBank number: MB 558543; Facesoffungi number: FoF 09195; Figs. 1, 2

Etymology – ‘longihelicospora’ referring to the asexual characters with long filamentous helicoid conidia.

Holotype – MFLU 21-0100

Saprobic on submerged decaying wood. Sexual morph Undetermined. Asexual morph Hyphomycetous, helicosporous. Colonies on natural substrate effuse, superficial, shiny, hairy, hyaline to white of crowded conidiospore masses. Mycelium composed of superficial and partly immersed, branched at the base, septate, hyaline to brown hyphae. Conidiophores macronematous, thick-walled, branched at the base, septate, pale brown to brown, smooth-walled. Conidiogenous cells monoblastic, terminal or intercalary, integrated, subhyaline, bearing lateral minute denticles. Conidia 36–52 µm diam., with conidial filament 4–5.5 µm wide, 252–360 µm long, loosely coiled 1–3½ times, becoming loosely uncoiled in water, rounded at apical ends, multi-septate, 33–45-septate, slightly constricted at the septa, hyaline to subhyaline, with granular contents.

Culture characteristics – Conidium germinating on MEA within 24 h and many germ tubes produced from conidium cells. Colonies growing on MEA, reaching greater than 10 mm diam. in 7 days at room temperature, effuse, sparsely hairy, radially striate, slightly fimbriate edge, dark brown, with yellow brown pigmented in the medium after 30 days. Mycelium superficial, partly immersed, branched, septate, hyaline, brown to dark brown hyphal filaments, asexual conidia not formed at 60 days.

Material examined – THAILAND, Chiang Rai Province, Muang, Mae Yao, Huay Mae Sai, on submerged decaying wood in a small freshwater stream, 17 March 2016, S. Boonmee, HMS07 (MFLU 21-0100, holotype), ex-type living culture, MFLUCC 16-0753.

GenBank numbers – ITS=MZ538531, LSU=MZ538565, TEF1-α=MZ567106.

Notes – Tubeufia longihelicospora is introduced as a new species based on morphological characters and phylogenetic evidence. Our new taxon forms a separate lineage basal to T. brunnea, T. hechiensis and T. taiwanensis with 100% MLBS, 1.00 BYPP support (Fig. 3). Tubeufia longihelicospora shares similar characteristics with T. hechiensis in having white colonies on natural woody substrates and multi-septate, hyaline, loosely coil conidia, but it differs in conidiophore and conidiogenous cell characters (Figs. 1 and 2). Furthermore, T. longihelicospora is distinguished from T. brunnea and T. taiwanensis by its macronematous, thick-walled, conidiophores and smaller, cylindrical filamentous conidia. A comparison of ITS nucleotide bases shows that T. longihelicospora differs from T. brunnea in 29/584 bp (5.3%), T. hechiensis in 28/546 bp (5.1%) and T. taiwanensis in 28/546 bp (5.1%) following the guidelines of Jeewon and Hyde (2016).

Figure 1 – Tubeufia longihelicospora (MFLU 21-0100, holotype). a Colony on decaying wood. b, c Conidiophores and lateral minute denticles. d–h Conidia. Scale bars: a=200 µm, b, c=10 µm, d–h=20 µm

Figure 2 – Tubeufia longihelicospora (MFLUCC 16-0753, ex-type). a Germinated conidium. b, c Culture on MEA from surface and reverse after 1 month. d–f Mycelium and development on culture (Note: the formation of chlamydospores). Scale bars: a, d–f=20 µm

Figure 3 –  Maximum likelihood phylogenetic tree based on a combined LSU, ITS and TEF1-α sequence dataset of Tubeufia taxa and related genera in Tubeufiaceae. Eighty-four strains are included in the combined analyses which comprise a total of 2395 characters. Pseudohelicomyces talbotii (MFLUCC 17-2021) is selected as the outgroup taxon. The best RAxML tree with a final likelihood value of − 11543.960875 is presented. RAxML analysis yielded 680 distinct alignment patterns and 15.58% of undetermined characters or gaps. Estimated base frequencies were as follows: A=0.238955, C=0.251270, G=0.256785, T=0.229079, with substitution rates AC=0.670086, AG=4.164732, AT=3.398524, CG=0.528840, CT=7.628422, GT=1.000000; gamma distribution shape parameter alpha=0.148685. Bootstrap support values for maximum likelihood (MLBS, left) equal to or greater than 70% is given above the nodes. Bayesian posterior probabilities (BYPP, right) equal to or greater than 0.95 are given above the nodes. Ex-type strains are in bold and newly generated sequences are in blue