Distoseptispora antiqueana Bagacay, E. B. G. Jones & M. S. Calabon 2026, sp. nov.

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Distoseptispora antiqueana Bagacay, E. B. G. Jones & M. S. Calabon sp. nov. Fig. 2 Etymology. Named after Antique Province, Philippines, where the fungus was first observed. Holotype. UPVMI 25–0078. Description. Saprobic on submerged decaying wood in intertidal 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 12–35 × 7–11 μm (x ¯ = 21.5 × 8.9 μm, n = 15), macronematous, mononematous, brown to dark brown, solitary, 2–4 - septate, erect, straight, or flexuous, unbranched, single or in groups of 2 or 3, smooth, cylindrical, truncate at the apex, slightly constricted at septa. Conidiogenous cells holoblastic, monoblastic, integrated, terminal, determinate, smooth, cylindrical. Conidia 139–268 × 9–16 (x ¯ = 201.6 × 12.9 μm, n = 30) acrogenous, solitary, dry, obclavate, cylindrical or rostrate, elongated, smooth-walled, straight or slightly curved, up to 39 - distosepta, 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 supplemented with sea water and produced germ tubes within 24 h. Colonies grown on PDA, circular, mycelium flat, dense, reaching 30–35 mm diam. after 30 days of incubation at 25 ° C, grey or brown, reverse-side dark brown. Material examined. Philippines, Antique, Anini-y, Nogas Island, on submerged wood from the intertidal zone, 30 September 2023, Jan Felnesh Exe Bagacay, NOG-005 (UPVMI 25–0078), living culture UPVMICC 25–0078. GenBank accession numbers. ITS = PZ 203859, RPB 2 = PZ 221688, TEF 1 - α = PZ 221699. Notes. In the multi-locus phylogenetic analyses, Distoseptispora antiqueana UPVMICC 25–0078 formed a well-supported, distinct lineage basal to a strongly-supported clade comprising D. thailandica (MFLUCC 16-0270), D. phangngaensis (MFLUCC 16-0857), D. hainanensis (GZCC 22-2047), D. multiseptata (MFLUCC 15-0609), and other closely-related taxa (100 MLBS, 1.00 BYPP; Fig. 1). BLASTn comparisons further support its phylogenetic distinction. The ITS sequence shows highest similarity to D. phangngaensis MFLUCC 16-0857 (99.15 %). However, protein-coding loci reveal lower similarity values: RPB 2 shows 96.88 % similarity to D. nanpingensis (HJAUP C 2517) and TEF 1 - α shows 94.69 % similarity to D. jinghongensis (HJAUP C 2120). Pairwise nucleotide comparisons further support the recognition of Distoseptispora antiqueana as a distinct species, differing from D. phangngaensis by 0.34 % (2 / 588 bp, ITS) and 7.56 % (73 / 965 bp, TEF 1 - α) sequence divergence. The introduction of Distoseptispora antiqueana, as with all novel taxa described in this study, follows the integrative species delimitation approach of Jeewon and Hyde (2016), whereby species are recognised, based on concordant phylogenetic evidence, nucleotide differences across informative loci and diagnostic morphological characters. Distoseptispora antiqueana differs from D. phangngaensis by having shorter, but wider conidiophores (12–35 × 7–11 μm vs. 18–30 (– 40) × 4.3–6.5 μm), shorter and narrower conidia (139–268 × 9–16 μm vs. 165–350 × 14–19 μm) (Yang et al. 2018). The observed interspecific divergence in the protein-coding genes, together with its independent phylogenetic position and morphological differences support its designation as a distinct species. This represents the second confirmed record of Distoseptispora from a marine habitat, isolated from submerged decaying wood in a mangrove ecosystem; the first such record is D. mangrovei reported from China (Li et al. 2026). Members of the genus are predominantly reported from freshwater and terrestrial environments; thus, this finding expands the known ecological range of the genus into marine-associated substrates (Calabon et al. 2022; Ma et al. 2022; Hu et al. 2023; Shen et al. 2024; Liao et al. 2025).

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