Wongia flava W.P. Wang, H.W. Shen, K.D. Hyde & Z.L. Luo, in Wang, Hyde, Bao, Wanasinghe, Lin, Shen, Lu, Zhang, Su, Li, Al-Otibi, Yang & Luo, Mycosphere 15(1): 6622 (2024)

Index Fungorum number: IF902437; MycoBank number: MB902437; Facesoffungi number: FoF16121

Etymology – flava = yellow, referring to the yellow colonies of this fungus.

Holotype – HKAS 131375

Saprobic on submerged decaying wood. Asexual morph: Colonies superficial, effuse, hairy, gathered, with yellow conidia located at the apex of the dark brown to black conidiophores. Mycelium partly immersed, partly superficial, composed of branched, septate, smooth-walled, pale brown hyphae. Conidiophores (67–) 100–160 × 4.7–6.1 µm (x̅ = 115.3 × 5.3 µm, n = 15), macronematous, mononematous, solitary, septate, erect, straight, brown to dark brown, paler towards the apex, smooth to slightly verrucose, thick-walled, occasionally branched at the apex or middle. Conidiogenous cells polyblastic, sympodially proliferating, finely denticulate, terminal, pale brown to brown. Conidia 18–24 × 5.3–7.9 µm, (x̅ = 21.5 × 6.9 µm, n = 30), acropleurogenous, solitary, fusiform or clavate, straight, 1–3 inconspicuous septate, slightly constricted in the middle septum, multiple guttulate, pale brown to brown. Sexual morph: Undetermined.

Culture characteristics – Conidia germinating on PDA within 12 h, and germ tubes produced at the both ends. Colonies on PDA reaching 35 mm diameter after 4 weeks at room temperature. Mycelium dense, dry, colonies on the surface of PDA, rugged surface, with irregular edges, dark green, and surface is covered with a layer of white hyphae. Reverse dark green, smooth, creak.

Material examined – China, Yunnan Province, Wenshan Zhuang and Miao Autonomous Prefecture, Bamei Town, on submerged decaying wood, 28 February 2023, W.P. Wang, S-4353 (HKAS 131375, holotype), ex-type living cultures CGMCC 3.25434 = KUNCC 23–13715.

Notes – Wongia flava was the fourth species of Wongia collected from a freshwater habitat and is clearly distinguishable from W. aquatica, W. fusiformis, and W. suae. Wongia flava has longer conidiophores ((67–) 100–160 vs. 70–105 µm) and larger conidia (18–24 × 5.3–7.9 vs. 13–18 × 4–5 µm) than those of W. fusiformis (Bao et al. 2021). Wongia flava differs from W. aquatica by its conidiogenous cells lacking pale brown scars, and the conidia is constricted at the central septum (Luo et al. 2019). Furthermore, W. flava has fusiform, larger conidia (18–24.2 × 5.3–7.9 vs. 8–11 × 3–4 µm) than W. suae, and the conidia are constricted in the middle septum (Zhang et al. 2023c). Comparison of the ITS sequences of W. flava (CGMCC 3.25434) with W. aquatica (MFLUCC 18– 1607), W. fusiformis (MFLUCC 21–0032), and W. suae (CGMCC 3.24295) revealed 10.31% (56/543 bp, 28 gaps), 5.96% (32/537 bp, ten gaps), and 5.93% (31/523 bp, eleven gaps) differences, respectively. Therefore, based on morphological characters and phylogenetic analysis, we introduce W. flava as a new species.

Figure 1 – Wongia flava (HKAS 131375, holotype). a Colonies on the substratum. b, d Conidiophores with conidia. c, e, f Conidiophores. g Conidiogenous cells. h Conidiogenous cell with conidium. i−l conidia. m Germinating conidium. n, o Colonies on PDA from surface and reverse. Scale bars: b−f = 20 µm, g, h, m = 10 µm, i−l = 5 µm.

Figure 2 – RAxML tree based on analysis of Papulosaceae that combined LSU, ITS, SSU, tef1-α, and rpb2 dataset. The combined analyses include 42 strains with 4024 characters including gaps (LSU: 798 bp, ITS: 524 bp, SSU: 914 bp, tef1-α: 850 bp, and rpb2: 938 bp). Bootstrap support values for maximum likelihood (ML) greater than 75% and Bayesian posterior probabilities greater than 0.95 are indicated above branches as ML/PP. The tree is rooted with Barbatosphaeria barbirostris (AFTOL-ID 967). The new collections are indicated in red. Ex-type strains are indicated with “T” after the strain number.