Hermatomyces sphaericoides Koukol & G. Delgado, IMA Fungus 9(1): 122 (2018)
Index Fungorum number: IF 824248; MycoBank number: MB 824248; Facesoffungi number: FoF 09190; Fig. 1
Saprobic on decaying wood. Sexual morph Undetermined. Asexual morph Hyphomycetous. Colonies on the natural substrate superficial, dry, scattered to partly grouped, black. Mycelium 2–3 μm wide, superficial and partly immersed, composed of branched, septate, pale brown or brown, sparsely network hyphae. Conidiophores micronematous, mononematous, flexuous, inconspicuous, septate, hyaline to pale brown. Conidiogenous cells 4–6×2–3 μm, holoblastic, monoblastic, integrated, terminal, determinate, cylindrical, pale brown. Conidia 25.5–32 × 21–27.5 μm (x̅=28.5×25 μm, n=20), solitary, acrogenous, cheiroid, globose to subglobose, inwardly curved at the apex, arising from a basal cell, consisting 4–5 rows, row digitate, each row composed of 4–5(–6) cells, multi-septate, constricted at the septa, dark brown to black, smooth-walled.
Culture characteristics – Conidium germinating on PDA within 24 h and germ tubes arising from terminal end of conidium. Colonies on PDA, fast growing, reaching 30 mm diam. after 2 weeks at room temperature, flat, with slightly crenated to radially striated with lobate margin, with white–grey mycelium, pastel grey in middle towards dark brown, greenish brown at margin, dark green to brown in reverse view, not sporulating in cultures after 2 months.
Material examined – THAILAND, Phetchabun Province, Lom Sak, on decaying wood, 25 July 2019, S. Boonmee, LSP01 (MFLU 21-0054, new record), living culture, MFLUCC 21-0077.
GenBank numbers – ITS=MZ538505, LSU=MZ538539, TEF1-α=MZ567083.
Notes – Hermatomyces sphaericoides was described on dry rotten twig of an unidentified tree in Panama and shares similar conidial features with H. sphaericus, but it differs in conidial characteristic details in having dark brown to blackish brown and finely verruculose with an outer ring of peripheral cells (Koukol et al. 2018). Furthermore, phylogenetic analyses indicate that H. sphaericoides and H. sphaericus are distinct species. Our strain MFLUCC 21-0077 shows some similarities with H. sphaericoides in terms of conidial characteristics (Koukol et al. 2018). Multi-gene phylogenetic analysis of a combined ITS, LSU and TEF1-α dataset indicated that our isolate MFLUCC 21-0077 clustered together with H. sphaericoides isolates (CCF 5896, CCF 5907, CCF 5908 (ex-type) and KZP 470) with 100% MLBS, 1.00 BYPP support (Fig. 2), whereas CCF 5895 forms a basal lineage. Therefore, we identify our collection as H. sphaericoides (Fig. 1) and it is reported here as a new geographical record from Thailand.
Figure 1 – Hermatomyces sphaericoides (MFLU 21-0054, new record). a, b Colonies on the natural substrate. c–e Conidiogenous cells. f–i Conidia. j Germinated conidium. k, l Culture on PDA from surface and reverse at 1 month. Scale bars: c–e, j=20 μm, f–i=10 μm
Figure 2 – Phylogram generated from maximum likelihood analysis based on combined ITS, LSU and TEF1-α sequence data of Hermatomyces taxa (Hermatomycetaceae) and closely related families Aquasubmersaceae and Anteagloniaceae. Elsinoecentrolobi CBS 222.50 and E. veneta CBS 150.27 are selected as the outgroup taxa. Bootstrap support values for maximum likelihood (MLBS, left) equal to or greater than 70% is given above or below 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