Phaeoacremonium philippinense M.S. Calabon, Bagacay, Nim, Sadaba & E.B.G. Jones

Calabon, Mark S., Bagacay, Jan Felnesh Exe, Nim, James Ariel, Sadaba, Resurreccion B., Ferriols, Victor Marco Emmanuel N., Concha, Michael Jee, Velo, Jasmine & Jones, E. B. Gareth, 2024, Phaeoacremonium philippinense (Togniniales, Sordariomycetes), a novel freshwater fungus from the Philippines, Phytotaxa 644 (3), pp. 177-189 : 183-185

Phaeoacremonium philippinense M.S. Calabon, Bagacay, Nim, Sadaba & E.B.G. Jones sp. nov.,

FIGURE 2 Mycobank number: MB 852555

Etymology:—in reference to Philippines, from where the holotype was collected.

Holotype:—UPVMI 23-0001

Saprobic on decaying wood submerged in freshwater. Sexual morph: Undetermined. Asexual morph: Hyphomycetous. Aerial structures in vitro on PDA: Mycelium 1.5–3 μm wide, consisting of branched, septate hyphae that occur singly or in bundles of up to six; hyaline to subhyaline, and smooth. Conidiophores 21–52 × 1.2–1.5 μm (x = 34.9 × 1.4 µm, n = 40), mostly of medium length, usually unbranched, arising from aerial or submerged hyphae, mostly erect, up to 4-septate, often ending in a single terminal phialide, hyaline to subhyaline, smooth. Phialides 1.5–3 × 1–1.5 μm, terminal or lateral, mostly monophialidic, smooth, hyaline to subhyaline, collarettes; type I phialides 3–16 × 0.9–3 µm (x = 8 × 1.4 µm, n = 30), predominate, mostly cylindrical to subcylindrical; type II phialides 8–14 × 1–3 µm (x = 10.7 × 1.8 µm, n = 30), mostly cylindrical, some navicular; type III phialides 18–24 × 1–2.5 µm (20.5 × 2.3 µm, n = 30), cylindrical, subulate. Conidia 2.5–4 × 0.7–1.2 µm (x = 3.6 × 1.1 µm, n = 30) hyaline, oblong-ellipsoidal or oblong, some allantoid. On surface or submerged in the agar: phialides 1.5–19 × 0.9–2.5 µm (7.1 × 2 µm, n = 30), hyaline, mostly cylindrical to subcylindrical. Conidia 2–4 × 0.5–1.2 µm (x = 3.2 × 0.9 µm, n = 30) hyaline, oblong-ellipsoidal to oblong.

Cultural characteristics:—Conidia germinating on PDA within 24 hours. Colonies on PDA reaching 35–40 mm diameter after 25 days at 25˚C. Mycelia superficial, circular, with filiform margin, flat, smooth, transparent, spare, from above gray to dark brown at the center then becoming white to brown at the margin; reverse, grayish brown at the center then becoming light brown to dark brown at the margin.

Material examined:— Philippines. Miagao, Iloilo, Tinagong Dagat lake, on submerged decaying wood of an unidentified plant, 11 March 2023, M.J. Concha, 01-OV-07 ( UPVMI 23-0001 , holotype), ex-living culture UPVMICC 23-0001 . Philippines. Miagao, Iloilo, Tinagong Dagat lake, on submerged decaying wood of an unidentified plant, 11 March 2023, M.J. Concha, 01-OV-08 ( UPVMI 23-0002 , paratype), ex-paratype living culture UPVMICC 23-0002 .

Notes:—Currently, there are four reported species of Phaeoacremonium in freshwater habitats: P. aquaticum ( Hu et al. 2012) , P. ovale ( Huang et al. 2018) , P. philippinense (in this study) and P. thailandense ( Calabon et al. 2021) . Phaeoacremonium philippinense shares the same morphology with other members of the genus, with short, usually unbranched conidiophores, presence of three types of phialides, and oblong-ellipsoidal to oblong conidia. The generic closest match of the sequences based on nucleotide BLAST searches in GenBank is Phaeoacremonium . Phaeoacremonium krajdenii (NCCPF No. 600006) is the closest species based on BLAST result of ITS region with 98.88% similarity. The actin sequence was 98.33% similar to Phaeoacremonium krajdenii (CBS 423.73), while tef1- α sequence was 96.82% similar to Phaeoacremonium minimum (UCRPA7). The multi-locus phylogenetic analyses show that P. philippinense is a distinct species and a sister taxon to P. thailandense with high bootstrap support (100% ML, 1.00 BYPP). Based on the ITS, act, and tef1-α sequence data, P. philippinense differs by 49 (8.06%, 608 bp), 65 (27.54%, 236 bp), and 62 (6.97%, 890 bp) base pairs with P. thailandense , respectively.

Figures

FIGURE 2. Phaeoacremonium philippinense (UPVMI 23–0001, holotype). Twenty-five-day old colonies on PDA, obverse (a), reverse (b). c–e Conidiophores, conidiogenous cells, and conidia. f, g Type I phialide. h–j Type II phialide. k, l Type III phialide. n Conidia. m, o–r Scanning electron micrograph (arrow: basal septum). Scale bar: c–r = 10 µm.