Distoseptispora motuoensis J.N. Li, R.J. Xu, Q. Zhao

Li, Jia-Ning, Xu, Rong-Ju, Xu, Ke, Zhao, Qi & Zhu, Ying-An, 2024, Distoseptispora motuoensis (Distoseptisporaceae), a new freshwater hyphomycetous species from Xizang Autonomous Prefecture, China, Phytotaxa 675 (2), pp. 122-134 : 129

Distoseptispora motuoensis J.N. Li, R.J. Xu, Q. Zhao & Y.A. Zhu, sp. nov. ( FIGURE. 2 )

Index Fungorum number: IF902004; Facesoffungi number: FOF 16023

Etymology: — The species epithet refers to Motuo County, where the holotype was collected.

Holotype:— HKAS 133193 .

Saprobic on submerged decaying wood in a freshwater stream. Sexual morph: Undetermined. Asexual morph: Hyphomycetous. Colonies effuse, olivaceous to brown, hairy or velvety. Mycelium partly superficial, partly immersed in the substrates, consisting of branched, septate, smooth, subhyaline to pale brown or greyish hyphae. Conidiophores 85–174 × 6–9 μm (= 132 × 7 μm, n = 20), macronematous, mononematous, unbranched, single or in groups, straight or slightly flexuous, cylindrical, olivaceous to brown, 4–7-septate, smooth. Conidiogenous cells 7–19 × 5–7 μm (= 10 × 6 μm, n = 20), monoblastic, integrated, terminal, monophialidic, determinate, olivaceous or dark brown, cylindrical. Conidia 39–88 × 9–15 μm (= 62 × 11 μm, n = 25), acrogenous, solitary, 7–12-distoseptate, elongate, obclavate, thick-walled, pale brown or olive-green, straight or slightly flexuous, tapering towards the rounded apex, truncate at base, slightly constricted at septa, smooth, sometimes with percurrent proliferation which forms another conidium from the conidial apex.

Culture characteristics: Conidia germinated on PDA within 48 h. Colonies on PDA growing up to 20 mm in diameter after two weeks at room temperature in natural light, colonies on PDA irregular, circular, flat, surface villiform, dense, dark brown mycelium in the center, celadon to grey from above, atrovirens from reverse, becoming sparse and paler at the entire margin, edge entire, not producing pigmentation on PDA.

Material examined: CHINA, Xizang Autonomous Prefecture, Motuo County, Dexing Town (29.354159°N, 95.148109°E), on submerged decaying wood in a freshwater stream, 10 August 2023, S.C. He, LJN-50 ( HKAS 133193 , holotype) ; ex-type living culture, KUNCC 24–17627 ; ibid LJN-65 ( HKAS 133194 , isotype), living culture, KUNCC 24–17628 .

Notes: Morphologically, Distoseptispora motuoensis resembles D.tectonae and D. mengsongensis in having effuse, hairy or velvety colonies, consisting of branched, septate, smooth, subhyaline to pale brown hyphae, macronematous, mononematous, cylindrical, brown conidiophores, and obclavate, olivaceous or brown, septate, rarely or slightly proliferating conidia ( Hyde et al. 2016, Luo et al. 2018, Liu et al. 2023). However, D. motuoensis can be distinguished from D. tectonae and D. mengsongensis in having longer (85–174 μm vs. 55–73 μm vs. 17–54 μm) conidiophores, shorter (39–88 μm vs. 190–255 μm vs. 86–200 μm) conidia and fewer septa (7–12-distoseptate vs. 20–28-distoseptate vs. 15–31-distoseptate) ( Hyde et al. 2016, Luo et al. 2018, Liu et al. 2023). Phylogenetic analysis showed that D. motuoensis clustered as a sister group with D. fluminicola with good support value (84% ML /0.81 PP). However, the latter species has more conidial septa (17–34-distoseptate vs. 7–12-distoseptate) and shorter conidiophores (21–33 × 5.5–6.5 μm vs. 85–174 × 6–9 μm). Moreover, D. fluminicola lacks proliferating conidia ( Su et al. 2016). Comparisons of sequence data between D. motuoensis ( KUNCC 24–17627) and D. fluminicola ( DLUCC 0999) showed 24/537 bp of ITS (4.5%, excluding gap), 2/705 bp of LSU (0.3%, excluding gap) and 20/875 bp of tef 1-α (2.3%, excluding gap) nucleotide differences in ITS, LSU, and tef 1-α regions, respectively. Therefore, the new species, D. motuoensis was proposed based on phylogenetic and morphological analyses ( Jeewon and Hyde 2016, Chethana et al. 2021).

Figures

FIGURE 2. Distoseptispora motuoensis (HKAS 133193, holotype). a Colonies on the substrate. b–e Conidiophores with conidia. f–k Conidia. l Germinated conidium. m, n Cultures on PDA. The arrow shows monophialidic conidiogenous cells. Scale bars: b–d = 50 μm, e = 100 μm, f– j = 20 μm, k, l = 50 μm.