Helicogermslita kunmingensis Y. Gao & H. Gui, sp. nov.

Index Fungorum number: IF 902400; Mycobank number: MB 902400; Facesoffungi number: FoF 15063; Fig. 1

Etymology – The specific epithet “kunmingensis” refers to Kunming City where the holotype was collected.

Holotype – HKAS 125556.

Saproubic on dead woody twigs. Sexual morph: Ascomata 570–950 μm diam×430–830 μm high (x̅=822×629 μm, n = 15), scattered, immersed, globose to subglobose or irregular, ostiolate. Peridium 72–100 μm wide, (x̅=86 μm, n=25), comprising an outer, brown, thick-walled, stratum of cells of textura angularis and inner, hyaline, thick-walled, stratum of textura irregularis cells. Hamathecium 3.5 –6 μm wide, (x̅=4.6 μm, n=20), septate, hyaline, unbranched, broad at base, tapering upwards. Asci 146–185×17–23 μm (x̅=160×19 μm, n=30), 8-spored, cylindrical, cylindricclavate, unitunicate, short pedicellate with foot-like pedicel, thick-walled at the apex, with apical apparatus tubular, bluing in Melzer’s reagent. Ascospores 20–29×11–13 μm (x̅=24×12 μm, n=30), initially hyaline, becoming dark brown at maturity, guttulate, fusiform or ellipsoid-inequilateral, with narrowly rounded ends, aseptate, spiral germ slit extending over the full length. Asexual morph: Not observed.

Culture characteristics – Ascospores germinated on PDA within 20 h and germ tube initially produced from both ends of the ascospores. Colonies on PDA reaching 20 mm in 4 weeks at room temperature (25–27 °C), failamentous, mycelium grows on the surface of PDA, white, Asexual spores and sexual spores were not formed on PDA within 60 days.

Material examined – China, Yunnan Province, Kunming City (25° 8′ 19″ N, 102° 44′ 25″ E), On dead woody twigs, 20 June 2021, Ying Gao, CCSG11 (HKAS 125556, holotype), ex-type, KUNCC 22-12535.

GenBank numbers – ITS: PQ036918, ITS: OP912879, rpb2: OP918020

Note – Based on our phylogenetic analysis of the combined LSU, ITS, rpb2 and tub sequence data, our novel species, Helicogermslita kunmingensis, is closely related to the strain of Helicogermslita clypeata with BYPP bootstrap supports (Fig. 2). Helicogermslita clypeata was introduced by Samarakoon et al. (2022), which have detailed morphological analysis and can be compared with our species Helicogermslita kunmingensis in peridium (29–45 μm vs. 72–100 μm), asci (115–145×9–11.5 μm vs. 146–185×17–23 μm), ascospores (13–18.5×5.7–7.5 μm, broadly ellipsoidal vs. 20–29×11–13 μm, fusiform or ellipsoid-inequilateral). and, a nucleotide pairwise comparison showed that Helicogermslita kunmingensis differs from Helicogermslita clypeata (MFLU 18–0852) in 75/545 bp of ITS (13.76%, with 19 gaps), 179/1042 bp of rpb2 (17.18%, with 6 gaps), 24/858 bp of LSU (2.8%, without gaps), Therefore, Helicogermslita kunmingensis is introduced here as a novel taxon based on the phylogeny with the guidelines for species delineation described in Chethana et al. (2021a, b) and Maharachchikumbura et al. (2021).

Figure 1 – Helicogermslita kunmingensis (HKAS 125556, holotype). a, b. Ascomata on dead woody twigs. c, d. Vertical section of the ascoma. e. Ostiole. f. Peridium. g. Hermathecium. h–k. Asci. l, m. Tubular ascalapical apparati in Melzer’s reagent. n–q. Ascospores. r. Germinatingascospore. s. Front colony on PDA. t. Reverse colony on PDA. Scale bars: d=200 μm. e=100 μm. f=30 μm. g=40 μm. h–k=30 μm. l–q=10 μm. r=30 μm

Figure 2 – The phylogenetic tree obtained inferred from a combined LSU, ITS, tub, and rpb2 sequence dataset representing the species of Xylariaceae strains were included in the combined analyses. Bootstrap support values for ML equal to or greater than 70%. The best RAxML tree with a final likelihood value of − 140614.819024 is presented. The matrix had 2627 distinct alignment patterns, with 40.86% of undetermined characters or gaps. Estimated base frequencies were as follows: A =0.237758, C =0.272136, G =0.249814, T =0.240293; substitution rates AC =1.293484, AG =4.807374, AT =1.149005, CG =1.072288, CT =7.777795, GT =1.000000; gamma distribution shape parameter α =0.776984. The tree is rooted to Hypoxylon fragiforme (HAST 383). The ex-type strains are in bold, and the new isolate of this study is in blue. Bar =0.06 estimated number of nucleotide substitutions per site per branch

Figure 2 – (continued)