Phaeoisaria filiformis D.F. Bao, Z.L. Luo, K.D. Hyde & H.Y. Su

Bagacay, Jan Felnesh Exe, Canto, Carr Marlo, Opiña, Lilcah Angelique, Nim, James Ariel, Velo, Jasmine, Lopez, Thomas Angelo, Ferriols, Victor Marco Emmanuel N., Sadaba, Resurreccion B. & Calabon, Mark S., 2025, Pleurotheciaceae in Philippine freshwater ecosystems: new records, asexual morph report of Phaeoisaria filiformis, and phylogenetic assessment, Phytotaxa 682 (2), pp. 121-137 : 127

Phaeoisaria filiformis D.F. Bao, Z.L. Luo, K.D. Hyde & H.Y. Su , Fungal Diversity 99: 564 (2019), FIGURE 2

Saprobic on submerged decaying wood. Sexual morph: see Luo et al. (2019). Asexual morph: Synnemata 285–850 × 8.7–32 μm (x̄ = 530 × 17.5 μm, n = 10), scattered, erect, rigid, dark brown to black, velvety, smooth. Conidiophores macronematous, synnematous, septate, cylindrical, branched, brown to dark brown, smooth. Conidiogenous cells 4.5– 34.5 × 1.3–3.3 μm (x̄ = 18.5 × 2.5 μm, n = 20), polyblastic, integrated, terminal, subhyaline to pale brown, smooth, denticulate, sympodial, each with several denticulate conidiogenous loci. Conidia 12.5–39.5 × 1.9–2.4 µm (x̄ = 20.7 × 2.1 µm, n = 20) solitary, fusiform to needle-shaped, straight or slightly curved, obtuse and tapering towards base, subhyaline to light brown, 3–4 septate, guttulate, smooth-walled.

Cultural characteristics:— Conidia germinating on PDA within 24 h. Colonies on PDA at room temperature reaching 30–35 mm diam. in three weeks at 25 °C, circular, slightly raised, entire, dry, surface rough, with sparse mycelium after four weeks, grayish brown in top view, reverse black, composed brown to dark brown, septate, smooth hyphae. Sporulation observed after 2 months in culture. Conidiophores macronematous, mononematous, cylindrical, straight or slightly flexuous, solitary, septate, unbranched, brown, paler towards the apex, denticulate conidiogenous cells. Conidiogenous cells polyblastic, integrated, terminal and intercalary, cylindrical, subhyaline to pale brown denticulate. Conidia 14–42.5 × 2–3.5 µm (x̄ = 22.3 × 3.3 µm, n = 40), solitary, fusiform to needle-shaped, straight, obtuse and tapering towards base, subhyaline to light brown, 3–4 septate, guttulate, smooth-walled.

Material examined:— Philippines, Bohol, Loon, Danicop-Ticugan Spring , on decaying wood submerged in a freshwater stream, 08 August 2023, T.A. R. Lopez, BHL-010-02-2 ( UPVMI 24–0006 ), living culture UPVMICC 24– 0006 ; Philippines, Bohol, Loon, Danicop-Ticugan Spring , on decaying wood submerged in a freshwater stream, 08 August 2023, T.A. R. Lopez, BHL-010-02-3 ( UPVMI 24–0007 ) .

Notes:—The isolate UPVMICC 24-0007 conforms to the asexual generic description of Phaeoisaria , characterized by indeterminate synnemata with septate or aseptate, ellipsoidal, obovoidal, fusiform-cylindrical, or falcate conidia ( Hyde et al. 2020). An ITS BLASTn search revealed the closest known species to the isolate are Phaeoisaria sp. ( HGUP-R 587), P. synnematica ( AMH:10055), and Phaeoisaria sp. ( CBS 143235). A multi-locus phylogenetic analysis revealed that the isolate grouped with P. filiformis strains, including the holotype MFLUCC 18-0124 and KUNCC:23- 13723 ( FIGURE 1 ). Phaeoisaria filiformis is closely related to P. synnematica ( FIGURE 1 ), but differs in conidiophore structure (solitary vs. compact, parallel appressed) and conidial morphology (filiform to needle-shaped, 3–4 septate vs. clavate to ellipsoidal, 0–1 septate) ( Boonmee et al. 2021). In this study, the new collection is identified as P. filiformis based on both morphological and phylogenetic analyses. This study presents the first report of P. filiformis from freshwater habitats in the Philippines and provides the first documented description of its asexual morph.

Figures

FIGURE 1. Phylogenetic tree generated from maximum likelihood (ML) analysis based on ITS, RPB2, and TUB2 sequence data for the species from Pleurotheciaceae. Bootstrap support values for maximum likelihood (ML) higher than 75% and Bayesian posterior probabilities (BYPP) greater than 0.90 are indicated above the nodes in this order. The new isolates are represented in blue. The ex-type strains are indicated in bold. The tree is rooted to Conioscypha hoehnelii (FMR 11592) and C. pleiomorpha (FMR 13134). Bar = 0.09 estimated number of nucleotide substitutions per site per branch.

FIGURE 2 Phaeoisaria filiformis (UPVMI 24–0006).(a) Host.(b, c) Colonies on naturalsubstrate.(d) Conidiophores.(e, f) Conidiogenous cells. (g, h) Conidiogenous cells and conidia. (i) Conidia. (j) Colony of mycelium on PDA. Microscopic characteristics on PDA: (k–n) Conidiophores, conidiogenous cells, and conidia. (o) Conidia. Scale bars for: b–d = 200 μm; e-h, k–n = 20 μm; i,o = 10 μm.