Kirschsteiniothelia dujuanhuensis H.W. Shen & Z.L. Luo, sp. nov.

Index Fungorum number: IF 557949; Mycobank number: MB 557949; Facesoffungi number: FoF 09289; Fig. 1

Etymology – Name reflects the location Dujuanhu Lake, Yunnan Province, China, from where the holotype was collected.

Holotype – KUN-HKAS 129177

Saprobic on unknown submerged wood in a freshwater lake. Sexual morph not observed. Asexual morph Hyphomycetous. Colonies scattered, effuse, brown to dark brown, glistening, hairy on natural substrate. Conidiophores 29–74(–119) × 9–11 μm (x̄= 51 × 10 µm, n = 15), macronematous, mononematous, darkbrown to dark, solitary, erect, cylindrical, straight or slightlycurved, slightly narrower towards the apex, unbranched, septate. Conidiogenous cells 8–10×7–8 μm (x̄=9×7 µm, n=15), monoblastic, cylindrical, integrated, terminal, brown to dark brown. Conidia (114–)122–155(–170)×10–13(–16) μm (x̄=138×12 µm, SD =17×2, n=15), brown to dark brown, obclavate, subcylindrical, solitary, straight, acrogenous, 6–15-distoseptate, constricted at septum, truncate at base, tapering towards apex, smooth-walled, with a spherical transparent mucilaginous sheath at the apex.

Culture characteristics – Conidia germinated on PDA within 24 h from single-spore isolation, germ tubes from both ends. Colony on PDA reaching 2.6 cm after 10 days at room temperature in dark, circular, brown on the surface rough, with dense, velvety mycelium, brown to dark brown from below.

Material examined – China, Yunnan Province, Puer City, Jingdong Yi Autonomous County, Dujuanhu Lake, 24° 32.53ʹ N, 101° 1.63ʹ E, on submerged decaying wood, 25 February 2022, H.W. Shen, YJ 30-51-1(KUN-KHAS 129177, holotype), ex-type KUNCC 22 12 671.

GenBank numbers – ITS = OQ874971, LSU = OQ732682, SSU = OQ875039.

Notes – Phylogenetic analysis combining LSU, SSU and ITS sequence data shows that Kirschsteiniothelia dujuanhuensis clustered as a sister clade with K. bulbosapicalis (GZCC 23-0732, unpublished data) with 100% ML and 1.00 PP (Fig. 2). Morphologically, K. dujuanhuensis differs from K. bulbosapicalis in having longer conidia (122–155 μm vs. 58.5 –128 μm) but shorter conidiophores (29–74 μm vs. 118–236.5 μm). Comparison of the ITS, LSU and SSU sequence data between K. dujuanhuensis and K. bulbosapicalis revealed 8.9% (55/508 bp, including 10 gaps), 1.2% (13/810 bp, including 3 gaps), and 0.2% (2/1003 bp) base differences, respectively. Here in we introduce K. dujuanhuensis as a new species, based on morphological and phylogenetic evidence.

Figure 1 – Kirschsteiniothelia dujuanhuensis (KUN-HKAS 129177, holotype) a, b Colonies on natural substrates. c–e, i Conidiophores with conidia. f, g Conidiogenous cells with conidia and sheath. h Conidium with sheath. j Germinated conidium. k, l Culture, k from above, l from reverse. Scale bars: c–e, h, i=30 µm, f, g=20 µm, j=40 µm

Figure 2 – Phylogram generated from maximum likelihood analysis based on combined LSU, SSU and ITS sequence datasets representing Kirschsteiniotheliales and other related families. The updated sequence dataset was derived from Sun et al. (2021). Forty-one strains are included in the combined analyses which comprise 2175 characters including gaps (814 characters for LSU, 874 characters for SSU, and 487 characters for ITS). Pseudorobillarda phragmitis (CBS:398.61) and P. eucalypti (MFLUCC 12–0422) were selected as the outgroup taxa. Phylogenetic trees generated from maximum likelihood and Bayesian inference analyses were similar in overall topologies. The best scoring RAxML tree with a final likelihood value of−16,923.208917 is presented. The matrix had 1079 distinct alignment patterns, with 28.13% undetermined characters or gaps. Estimated base frequencies were as follows: A=0.235516, C=0.242244, G=0.301606, T=0.220634; substitution rates AC=0.932755, AG=2.403934, AT=0.957895, CG=1.206625, CT=5.593191, GT=1.000000; Tree-Length=2.712710; gamma distribution shape parameter α=0.375105. Bayesian posterior probabilities (BYPP) from MCMC were evaluated with a final average standard deviation of split frequencies less than 0.01. Bootstrap support values for maximum likelihood (ML) equal to or greater than 70% and Bayesian posterior probabilities (BYPP) equal to or greater than 0.97 are defined above the nodes as ML/BYPP. The type strains are indicated in bold and newly generated sequence are shown in blue