Distoseptispora chiangraiensis R.J. Xu, Q. Zhao & K.D. Hyde sp. nov.

Index Fungorum number: IF 902394; Mycobank number: MB 902394; Facesoffungi number: FoF 16060 Fig. 1

Etymology – Referring to the collection site from Chiang Rai Province in Thailand.

Holotype – MFLU 21-0105

Saprobic on submerged decaying wood in a freshwater stream. Sexual morph: Not observed. Asexual morph: Colonies effuse, olivaceous or dark brown, hairy or velvety, glistening. Mycelium partly superficial, partly immersed in the substrate, consisting of branched, septate, smooth, subhyaline to pale brown hyphae. Conidiophores 35–64×4.0–6 μm (x̅ = 51×5 μm, n=16), macronematous, mononematous, unbranched, single or in groups of 2 or 3, erect, cylindrical, straight, or slightly flexuous, brown to olivaceous, 3–4-septate, smooth, truncate at the apex. Conidiogenous cells monoblastic, integrated, terminal, olivaceous or brown, cylindrical, sometimes with percurrent proliferation. Conidia 68–172×6.5–11 μm (x̅ = 114×9 μm, n=25), acrogenous, solitary, elongate, tapering towards at the apex, obclavate, rostrate, truncate at base, rounded at apex, 15–25-distoseptate, slightly constricted at septa, thick-walled, olivaceous to dark brown, pale brown to subhyaline towards the apex, smooth, guttulate, sometimes with percurrent proliferation which forms another conidium from the conidial apex.

Culture characteristics – Conidia germinated on MEA within 48 h and germ tubes from both ends. Colony reached 26 mm at 28 °C for 3 weeks, on MEA media, circular, flat, surface villiform, dense, dark brown mycelium in the center, celadon to grey from above, atrovirens from below, becoming sparse and paler at the entire margin, edge entire.

Material examined – Thailand, Chiang Rai Province, Nang Lae, Mueang, (99° 52′ 52.93″ E, 20° 3′ 2.52″ N), saprobic on decaying bamboo culms, submerged in a freshwater stream, 18 July 2020, R.J Xu, MD-70C (MFLU 21-0105, holotype), ex-type living culture (T20-1126). saprobic submerged decaying wood of an unidentified plant in a freshwater stream, 18 July 2020, R.J Xu, MD-70D (HKAS 115808, isotype), living culture, MFLUCC 24-0112, KUNCC 10443.

GenBank numbers – MFLU 21-0105: ITS= MZ890145, LSU=MZ890139, SSU=MZ890181, tef1-α=MZ892970. KUNCC 10443: ITS = MZ890146, LSU = MZ890140, SSU=MZ890182, tef1-α=MZ892971

Notes – In the phylogenetic analyses, our isolates developed a sister clade with D. bangkokensis (MFLUCC 18-0262) with 98% ML bootstrap and 1.00 BYPP statistical support. Morphologically, D. chiangraiensis resembles D. bambusae and D. obclavata in having macronematous, cylindrical, brown to olivaceous, septate conidiophores and obclavate, olivaceous or brown conidia (Sun et al. 2020; Luo et al. 2019). However, D. chiangraiensis can be distinguished from D. bambusae in having elongate, longer conidia (68–172 μm vs. 45–74 μm). Distoseptispora chiangraiensis differs from D. obclavata in having shorter conidiophores (35–64×4.0–6 μm vs. 117.5–162.5×5–7 μm), and longer conidia (68–172 × 6.5–11 μm vs. 46–66 × 9–11 μm) (Luo et al. 2019; Sun et al. 2020; Sheng et al. 2021). Distoseptispora chiangraiensis resembles D. bangkokensis in having macronematous, mononematous, cylindrical conidiophores, terminal, monoblastic, cylindrical conidiogenous cells, and acrogenous, solitary, elongate, multidistoseptate conidia (Shen et al. 2021). However, it differs in having shorter conidia (68–172 × 6.5–11 μm vs. 400–568 × 13–16 μm). Additionally, comparisons of ITS sequences demonstrate a 2.9% (15/522 bp, excluding gaps) difference between D. chiangraiensis and D. bangkokensis Jeewon and Hyde (2016). Therefore, D. chiangraiensis was identified as a new species supported by both morphological and phylogenetic evidences.