Distoseptispora bambusicola X. Tang, Jayaward, J.C Kang & K.D. Hyde sp. nov.

Index Fungorum number: IF 558533; MycoBank number: MB 558533; Facesoffungi number: FoF 09940; Fig. 1

Etymology – Named after the host bamboo from which the holotype was found.

Holotypus – GZAAS21-0379.

Saprobic on decaying stems of bamboo submerged in a freshwater stream habitat. Sexual morph: Not observed. Asexual morph: Colonies effuse, scattered, hairy, brown to dark brown. Mycelium mostly immersed, composed of branched, septate, brown, smooth hyphae. Conidiophores macronematous, mononematous, pale brown to brown, solitary, 4–7-septate, erect, straight or flexuous, unbranched, slightly constricted at septa, smooth, cylindrical, 64–116 μm×4–7 μm (x̄ =90.5×5.5 μm, n=30), truncate at the apex. Conidiogenous cells holoblastic, monoblastic, integrated, terminal, determinate, brown, cylindrical. Conidia 72–193 μm×7.5–14.5 μm (x̄ =126×14 μm, n=30) acrogenous, solitary, obclavate or lanceolate, rostrate, straight or slightly curved, multi-distoseptate, up to 16-distoseptate, guttulate, pale brown, tapering towards the rounded apex, truncate at the base, slightly constricted at septa, smooth-walled, rounded at apex, with a truncate base and faintly to heavily pigmented scar.

Culture characters – Colony grown on PDA in room temperature, circular, fluffy, white, dense in the center, but sparse, slightly olivaceous in the outside. In reverse, deeply olivaceous in the center, slightly yellow at the entire margin. Refer to the pigment produced on PDA and OA, purpure.

Material examined – China, Guizhou Province, Zunyi City, on decaying stems of bamboo submerged in a freshwater stream, 21 February 2021, Xia Tang, K1 (GZAAS21- 0379, holotype), ex-type living culture, GZCC21-0667.

GenBank numbers – MZ474873 (ITS), MZ474872 (LSU), MZ474866 (SSU), OM272845 (tef1).

Notes – Distoseptispora bambusicola clustered with D. hydei, D. obpyriformis and D. rostrata with a 100%ML, 99%MP and 1.00 BYPP support. According to the morphological comparisons (Fig. 2), our novel species can be distinguished from closely related species. Distoseptispora bambusicola differs from D. rostrata by its smaller conidiophores (64–116 μm ×4–7 μm vs 82–126 μm ×5–7 μm), larger conidia (72–193 μm × 7.5–14.5 μm vs 115–155 μm × 9–11 μm) and less distosepta (16-distosepta vs 23-distosepta). Distoseptispora bambusicola shares similar morphological characteristics with D. obpyriformis in the size, shape, color of conidiophores, but differ in conidial size (72–193 μm × 7.5–14.5 μm vs 53–71 μm×12–16 μm). Distoseptispora bambusicola differs from D. obpyriformis by having obclavate or lanceolate, longer conidia. Distoseptispora bambusicola can be distinct from Distoseptispora hydei by conidal shape and size (72–193 μm×7.5–14.5 μm vs 32–58 μm×10–15 μm; obclavate or lanceolate vs obpyriform to fusiform). Distoseptispora hydei is characterized with a gelatinous sheath around the tip of conidia, while D. bambusicola lacks this character. According to the comparisons of our novel species with other phylogenetically related taxa based on a pairwise nucleotide comparison of ITS (Jeewon and Hyde 2016), D. bambusicola differs from D. rostrata in 13/ 517 bp (2.5%), D. hydei in 8/ 395 bp (2.0%) and differs from D. obpyriformis in 25/571 bp (4.0%). Pairwise nucleotide comparison of LSU and tef1 also showed that D. bambusicola differs from D. rostrata in 10/ 826 bp (1.2%) for LSU and 42/ 857 bp (4.9%) for tef1, differs from D. hydei in 7/ 848 bp (0.8%) for LSU, and differs from D. obpyriformis in 6/ 790 bp (0.7%) for LSU and 40/ 838 bp (4.7%) for tef1. Thus, we consider D. bambusicola as a novel species in Distoseptispora.

Figure 1 – Distoseptispora bambusicola (GZAAS21-0379, holotype). a, b Colonies on dead wood c–e Conidiophores f Cnidiogenous cell g–n Conidia o Germinated conidia p, q Colony on PDA (up-front, down-reverse). Scale bars: c–j=20 μm, k–o=50 μm

Figure 2 – Phylogram generated from parsimony analysis based on combined ITS, LSU, SSU, rpb2 and tef1 sequence data of Distoseptispora. The ML and MP bootstrap support values≥70% are and branches with BYPP≥0.95 are given above the nodes. The ex-types (reference strains) are in bold; the new isolates are in blue bold. The tree is rooted with Aquapteridospora fusiformis (MFLU 18–1601), Aquapteridospora lignicola (MFLUCC 15–0377) and Aquapteridospora aquatica MFLUCC 17–2371)