Distoseptispora septata Jian Ma & Y. Z. Lu

Résumé fourni par la source

Distoseptispora septata Jian Ma & Y. Z. Lu, J. Fungi 8 (no. 1202): 15 (2022) Fig. 5 Description. Saprobic on submerged decaying wood in freshwater habitat. Sexual morph: Undetermined. Asexual morph: Colonies superficial, effuse, gregarious, brown or dark brown, hairy. Mycelium mostly immersed, composed of branched, septate, smooth, pale brown to brown hyphae. Conidiophores up to 20 μm, macronematous, mononematous, brown to dark brown, solitary, 2–3 - septate, erect, straight or flexuous, unbranched, single or in groups of 2, smooth, cylindrical, truncate at the apex, slightly constricted at septa. Conidiogenous cells holoblastic, monoblastic, integrated, terminal, determinate, smooth, cylindrical. Conidia 129–220 × 9–15 μm (x ¯ = 159.5 × 12.4 μm, n = 30) acrogenous, solitary, dry, obclavate, cylindrical or rostrate, elongated, smooth-walled, straight or slightly curved, up to 46 - distoseptate, guttulate, olivaceous to dark brown, mostly slightly constricted at septa, tapering towards the rounded apex, truncate at the base. Conidial secession schizolytic. Culture characteristics. Conidia germinated on potato dextrose agar and produced germ tubes within 24 h. Colonies grown on PDA, circular, mycelium flat, dense, reaching 30–40 mm diam. after 30 days of incubation at 25 ° C, grey or brown, reverse-side dark brown. Material examined. Philippines, Iloilo, Calinog, on submerged decaying wood in a freshwater stream, 3 October 2023, James Ariel Nim, CALINOG-004-03-001 (UPVMI 25–0088), living culture UPVMICC 25–0088. GenBank accession numbers. ITS = PZ 203856, LSU = PZ 208526, RPB 2 = PZ 221686, TEF 1 - α = PZ 221696. Notes. Distoseptispora septata was introduced by Ma et al. (2022) from submerged decaying wood in a freshwater stream in China. Both strains, GZCC 22-0078 (holotype) and UPVMICC 25–0088, were collected as saprobes on submerged woody substrates in freshwater habitats and conform well to the generic circumscription of Distoseptispora. Distoseptispora septata GZCC 22-0078 possesses longer conidiophores (23–86 μm, up to 6 - septate) and comparatively shorter conidia (22–179 × 10–16 μm, mean 89 × 13 μm) with up to 25 distosepta and reportedly verrucose conidial walls (Ma et al. 2022). In contrast, UPVMICC 25–0088 is characterised by shorter conidiophores (≤ 20 μm, 2–3 - septate) and markedly longer conidia (129–220 × 9–15 μm, mean 159.5 × 12.4 μm) bearing up to 46 distosepta. Phylogenetically, UPVMICC 25–0088 clusters with the holotype strain GZCC 22–0078 with maximal statistical support (100 % MLBS, 1.00 BYPP). Nucleotide comparisons reveal no differences in the ITS and RPB 2 loci, while minor variation is observed in LSU (3 / 821 bp; 0.37 %) and TEF 1 - α (2 / 915 bp; 0.22 %). Although differences were observed in conidiophore and conidial dimensions, species delimitation in Distoseptispora is based on the integration of morphological characteristics and multilocus phylogenetic evidence and morphological variation amongst conspecific collections has been documented within the genus (Hyde et al. 2020; Yang et al. 2021). Therefore, the strong phylogenetic support and low sequence divergence across multiple loci confirm that UPVMICC 25–0088 and GZCC 22–0078 represent conspecific isolates of D. septata, with the observed morphological differences falling within the species’ phenotypic range. This study represents a new geographic record of D. septata.

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