Torula lancangjiangensis H.W. Shen, S. Boonmee, Z.L. Luo & K.D. Hyde, sp. nov.

Index Fungorum number: IF 558159; MycoBank number: MB 558159; Facesoffungi number: FoF 09753; Fig. 1

Etymology – Referring to the collecting site from the Langcangjiang River in China.

Holotype – HKAS 112709

Saprobic on submerged wood in a freshwater habitat. Sexual morph Undetermined. Asexual morph Colonies sparse, hairy, dry, velvety, dark brown to black on substrate. Mycelium partly immersed to superficial on the substrate, septate, branched, light brown to brown hyphae. Conidiophores 5–15×3–4 μm (x̅=10×3 μm, n=25), macronematous to semi- macronematous, mononematous, erect, straight or slightly flexuous, without apical branches, light brown to brown, ellipsoid to subcylindrical, smooth-walled, 0–2-septate, with 1–2 doliiform to globose cells. Conidiogenous cells 5–7×5–6 μm (x̅=6×5 μm, n=25), polyblastic, integrated, terminal or intercalary, doliiform to subglobose, brown to dark brown, smooth to verrucose, thick-walled. Conidia (24–)45–74(–100) × 6–7(–8) μm (x̅=60 × 7 μm, n=40), acrogenous, catenated, composed of moniliform cells, brown to dark brown, 5–19-septate, constricted at the septa, doliiform to globose, most circular–drum form, with 1–2 cells black at the apex. Conidial secession schizolytic.

Culture characteristics – Conidia germinated on PDA within 24 h, and germ tube produced from the conidial cells at both ends or in the middle. Colonies grow on the PDA, and after incubating at room temperature for 1 month, the diameter reaches to 3.5 cm. Hyphae are initially light gray, turning dark grey at maturity, raised in the middle, flocculent, velvety, white, with edges smooth, light grey to light brown. Reverse light grey in the middle light gray to dark grey, smooth edges.

Material examined – CHINA, Yunnan Province, Xishuangbanna, (100°42′04″ E 22°05′19″ N, 680 msl), on submerged wood, 4 May 2018, H.W. Shen, Q.S. Zhou and Z.L. Luo, S-2043 (HKAS 112709, holotype, MFLU 21-0112, isotype), ex-type living culture, DLUCC 2043; THAILAND, Chiang Rai, Muang, Thasud, Mae Fah Lung University, Botanical garden, on dead twigs, 15 November 2018, Boonmee, B03 (MFLU 21-0076), living culture, MFLUCC 21-0099.

GenBank numbers – DLUCC 2043: ITS= MW723059, LSU = MW879526, SSU = MW774582, RPB2 = MW729780, TEF1-α = MW729785; B03: ITS=MZ538529, LSU=MZ538563, TEF1-α=MZ567104.

Notes – In a NCBI BLASTn search based on RPB2 sequences, the closest match of Torula lancangjiangensis was T. camporesii (KUMCC 19-0112; GenBank no. MN507404) with 97.67% similarity. A comparison of RPB2 nucleotide bases indicated that T. lancangensis differs from T. camporesii in 50/1055 bp (4.7%). In addition, multigene phylogenetic analysis of a combined dataset of the LSU, SSU, TEF1-α, RPB2, and ITS showed that T. lancangjiangensis and T. camporesii are close relatives with 95% MLBS, 1.00 BYPP support (Fig. 2). Torula lancangjiangensis resembles T. camporesii in having ellipsoid to subcylindrical, multi-septate conidia; and doliiform to subglobose, brown to dark brown conidiogenous cells (Fig. 1). However, conidial cells of T. camporesii are wide in the middle and small at the ends, while the cells of T. lancangjiangensis are more uniform. Therefore, Torula lancangjiangensis is introduced as a new species.

Figure 1 – Torula lancangjiangensis (HKAS 112709, holotype). a, b Colonies on submerged wood. c–f Conidiophores with conidiogenous cells. g, h Conidiophores, conidiogenous cells with conidia. i–k Conidia. l Conidia in chain. m Germinated conidium. n Culture on PDA from surface and reverse. Scale bars: c–m=20 μm

Figure 2 – Phylogram generated from maximum likelihood analysis based on combined LSU, SSU, TEF1-α, RPB2 and ITS sequence dataset representing genera of Torulaceae and other related families in Pleosporales. The updated sequence dataset was derived from Hyde et al. (2020b) and Li et al. (2020a). Forty-seven strains are included in the combined analyses which comprise a total of 4193 characters. Paeadictyoarthrinium diffractun MFLUCC 13-0466 and P. hydei MFLUCC 17-2512 are selected as the outgroup taxa. The best RAxML tree with a final likelihood value of − 20632.568415 is presented. RAxML analysis yielded 1256 distinct alignment patterns and 34.11% of undetermined characters or gaps. Estimated base frequencies were as follows: A=0.246275, C=0.259573, G=0.270969, T=0.223183, with substitution rates AC=1.544243, AG=3.270041, AT=1.437706, CG=0.944551, CT=7.854806, GT=1.000000; gamma distribution shape parameter alpha=0.178530. 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