Hongkongmyces kokensis Boonmee, Chandrasiri, Huanraluek & K.D. Hyde, sp. nov.
Index Fungorum number: IF 558535; MycoBank number: MB 558535; Facesoffungi number: FoF 09946; Fig. 1
Etymology – The specific epithet “kokensis” refers to the Kok river.
Holotype – MFLU 21-0056
Saprobic on submerged decaying wood in the river. Sexual morph Undetermined. Asexual morph Coelomycetous. Conidiomata 261–347 μm high, 264–417 μm diam., pycnidial, scattered, semi-immersed or erumpent, subglobose or ellipsoidal, dark brown to black, coriaceous, ostiolate. Conidiomata wall 13–38 μm thick, composed of several layers of dark brown cells of textura angularis, difficult to distinguish from conidiogenous cells. Conidiophores reduced to conidiogenous cells. Conidiogenous cells 7–21×3–12 μm (x̅= 12 × 6 μm, n = 10), phialidic, determinate, cylindrical to subcylindrical, hyaline, thin-walled. Conidia 10–15×8–14 μm (x̅=12×10 μm, n=20), subglobose to obovoid, hyaline, aseptate, large guttule present when immature, lacking a mucilaginous sheath, smooth-walled.
Culture characteristics – Conidia germinated on PDA within 24 h. Colonies on PDA reaching 3.5 cm diam. after 3 weeks at room temperature, circular, entire to slightly undulate edge, raised effuse, olivaceous brown to brown from the center towards margin, surrounded by light brown at the margin, dark brown at the reverse with surrounded by light brown at the margin, superficial and velvety mycelia.
Material examined – THAILAND, Chiang Rai Province, Muang, Mae Yao, Kok river, on submerged decaying wood in the river shore, 4 December 2019, S. Boonmee and K.S.U. Chandrasiri, N-KR4 (MFLU 21-0056, holotype), ex-type living culture, MFLUCC 21-0079; Chiang Rai Province, Wiang Pa Pao, Lao River, on submerged decaying wood in the river shore, 11 December 2019, S. Boonmee and K.S.U. Chandrasiri, LR4 (MFLU 21-0057), living culture, MFLUCC 21-0080; Phrae, Pong, Yom River, on submerged decaying wood in the river shore, 18 December 2019, S. Boonmee and K.S.U. Chandrasiri, YR21 (MFLU 21-0058), living culture, MFLUCC 21-0081.
GenBank number – LR4: ITS = MZ538507, LSU = MZ538541, TEF1-α = MZ567085; N-KR4: ITS=MZ538506, LSU=MZ538540, TEF1-α=MZ567084; YR21: ITS = MZ538508, LSU = MZ538542, TEF1-α=MZ567086.
Notes – Multigene phylogenetic analysis of a combined LSU, ITS and TEF1-α sequence dataset indicated that Hongkongmyces kokensis forms a sister clade with the sexual species H. thailandica with 97% MLBS and 1.00 BYPP support (Fig. 2). A comparison of LSU and ITS base pair shows that H. kokensis differs from H. thailandica with by 14/788 bp (1.77%) of LSU and 86/994 bp (8.65%) with 21 gaps of ITS. Furthermore, the morphological characters of H. kokensis and H. thailandica could not be directly compared as they represent as different morphs (Hyde et al. 2017). Hongkongmyces kokensis also shares some morphological features of conidiomata and conidia with H. aquaticus (Dong et al. 2020b), but they differ in shape and size of conidiomata and conidia (Fig. 1). However, phylogenetic analysis indicates that H. kokensis is a distinct species from H. aquaticus and H. thailandica. We therefore, introduce Hongkongmyces kokensis as a new species following the guidelines of Jeewon and Hyde (2016). The addition of protein coding gene data would likely strengthen the distinction of the new taxa.
Figure 1 – Hongkongmyces kokensis (MFLU 21-0056, holotype). a, b Appearance of conidiomata on submerged decaying wood substrate. c, d Section through conidiomata. e Section of conidioma wall. f–h Conidiogenous cells and conidia. i, j Conidia. k Germinated conidium. l, m Culture on PDA (l=from above, m=from below). Scale bars: c=50 µm, d=200 µm, e, g, h=20 µm, f, i, k=10 µm, j=5 µm
Figure 2 – Phylogram generated from maximum likelihood analysis based on combined LSU, SSU, ITS, and TEF1-α sequence data of new species and new genus in Lindgomycetaceae. Astrosphaeriella neofusispora MFLUCC 11-0161 and A. fusispora MFLUCC 10-0555 are selected as the outgroup taxa. Bootstrap support values for maximum likelihood (MLBS, left) equal to or greater than 70% is given above the nodes. Bayesian posterior probabilities (BYPP, right) equal to or greater than 0.95 are given above the nodes. Ex-type strains are in bold and newly generated sequences are in blue