Distoseptispora aquisubtropica J Ma, K. D. Hyde & Y.Z. Lu, sp. nov. (Figure 4).
MycoBank number: MB; Index Fungorum number: IF; Facesoffungi number: FoF 11334;
Etymology: ‘aquisubtropica’ from subtropical meaning climate type and aqui referring to its presence in water.
Saprobic on decaying wood submerged in freshwater habitats. Sexual morph: Undetermined. Asexual morph: hyphomycetous. Colonies on natural substrate superficial, effuse, gregarious, smooth, septate, hairy, brown or dark brown. Mycelium mostly immersed, composed of branched, septate, smooth, pale brown to brown hyphae. Conidiophores 15.6–83 μm × 4.8–11 μm (x̅ = 51 × 8 μm, n = 25), macronematous, mononematous, cylindrical, erect, simple, straight or slightly flexuous, unbranched, Smooth, thick-walled, smooth-walled, solitary, brown at the base, pale brown or subhyaline towards the apex, 2-5-septate. Conidiogenous cells 3.2–10.5 × 3.2–6.9 μm (x̅ = 6.0 × 5.3 μm, n = 25), holoblastic, monoblastic, terminal, integrated, cylindrical, pale brown or brown, smooth. Conidia 42.5–278 × 11.1–19 μm (x̅ = 14.6 × 140.6 μm, n = 38), acrogenous, solitary, multi-distoseptate, obclavate or lanceolate, rostrate, straight or slightly curved, verruculose, guttulate, thick-walled, smooth-walled, pale brown or dark brown, olivaceous, 16-31-distoseptate, usually paler towards apex, with conspicuous hyphae attachment conidium, rounded at apex, with a truncate base.
Culture characteristics: Conidia germinating on PDA within 12 h. and germ tubes produced from conidia. Colonies growing on PDA, reaching 34 mm diam. in 25 days at 25°C, circular, flat, with dense, dark gray, fluffy, break in the center, from below olivaceous brown at the center, yellow at the entire margin.
Material examined: China, Guizhou Province, Zhenyuan, on decaying wood submerged in a freshwater stream, 01 May 2021, Jian Ma, XXJ11-3 (GZAAS22-0080, holotype), ex-type living culture, GZCC22-0075.
GenBank accession numbers: (LSU), (ITS), (TEF1α) ON, (RPB2) ON.
Notes: D. martinii has monoblastic, integrated, smooth, terminal, cylindrical, with 0-2 percurrent extensions, subhyaline to pale brown conidiogenous cells and solitary, dry, transversal ellipsoid, oblate or subglobose conidia. The morphology of Distoseptispora aquisubtropica is not similar to D. martinii in size and shape of conidia. However, the phylogenetic results show that our new collection (D. aquisubtropica) forms a sister clade to D. martinii with relatively well-supported values (83% ML and 1 BYPP). In a BLASTn search on NCBI GenBank, the closest match of the ITS and SSU sequence of our new isolate (D. aquisubtropica) were 92.95% similarity across 85% of the query sequence and 99.6% similarity across 86% of the query sequence to D. martinii and D. aquisubtropica, respectively. Based on a pairwise nucleotide comparison of ITS and LSU, D. aquisubtropica differs D. martinii in 24/453bp (5.3%) for ITS, and 5/515 bp (0.97%) for LSU, respectively, Therefore, we identified D. as the novel species following the guidelines for species delineation proposed by Jeewon and Hyde.
Figure 4. Distoseptispora aquisubtropica (GZAAS22-0080, holotype) a–b Colonies on natural substrate. c–g Conidiophores, conidiogenous cells bearing conidia. h–k Conidia. l Germinating conidium. m, n Culture on PDA from above and reverse. Scale bars: c–l = 20 μm