Acrocalymma fici Crous & Trakun., IMA Fungus 5(2): 405 (2014)
Index Fungorum number: IF 810838; MycoBank number: MB 810838; Facesoffungi number: FoF 09155; Fig. 1
Saprobic on submerged decaying wood. Sexual morph Undetermined. Asexual morph Conidiomata 80–200×40–120 μm (x̅=110×85 µm, n=10), pycnidial, globose to subglobose, erumpent, separate but aggregated in clusters, sub-hyaline with dark brown to black region around ostiole. Pycnidial wall 41–55 μm diam., 3–6 layers of hyaline to subhyaline cells of textura angularis. Conidiophores reduced to conidiogenous cells. Conidiogenous cells 4–15×2–5 µm (x̅=7×3 µm, n=20), ampulliform to doliiform, hyaline, smooth, 5–12 × 3–5 μm, with inconspicuous percurrent proliferation visible at apex. Conidia 12–15×2–3 µm (x̅=13×3 µm), hyaline, smooth, guttulate, cylindrical, with subobtuse at the apex, acutely tapered at base to a small flattened central scar, 0–1-septate, not constricted at septum, with flaring mucoid apical appendage, 2–5 μm wide, visible in water mounts.
Culture characters – Conidia germinated on MEA within 24 h. Colonies on MEA reaching 4–5 cm after 4 weeks at room temperature, colonies irregular, medium dense, flat with smooth and filiform margins; white to smoke-grey in top view, reverse yellowish orange in center and yellowish in the outer region.
Material examined – THAILAND, Kanchanaburi Province, Sangkhla Buri, Liwo, on submerged decaying wood in a stream, 27 June 2019, N. Chaiwan, TFW5 (MFLU 21-0124, new habitat and geographical record), living culture, MFLUCC 21-0103.
GenBank numbers – ITS=MT864351, LSU=MT860429.
Notes – Acrocalymma fici, introduced by Trakunyingcharoen et al. (2014), was collected from Ficus sp. in a terrestrial habitat. Based on phylogenetic analysis of combined LSU and ITS sequence data, our isolate MFLUCC 21-0103 clustered with the ex-type strain of Acrocalymma fici (CBS 317.76) with 96% MLBS and 97% MPBS bootstrap support (Fig. 2). Our isolate resembles A. fici in shape and size of the conidiomata, conidiogenous cells and conidia (Fig. 1). Moreover, there are no base pair differences of the ITS nucleotides. However, Acrocalymma fici strain CBS 317.76 was isolated from a terrestrial host, Ficus sp., while our isolate was collected from a freshwater habitat. Therefore, we report this isolate as a new record of A. fici from a freshwater habitat.
Figure 1 – Acrocalymma fici (MFLU 21-0124, new habitat and geographical record). a, b Appearance of erumpent fruiting bodies on host substrate. c Section through conidioma. d Section through pycnidial wall. e, f Immature and mature conidia attached to conidiogenous cells. g–j Conidium. k Germinated conidium l, m Culture on MEA (upper and lower view). Scale bars: a=500 μm, b=200 μm, c=100 μm, d, f, h–k=10 μm, e=5 μm, g=20 μm
Figure 2 – Phylogenetic tree generated from maximum likelihood (ML) analysis based on combined LSU and ITS sequence data for the species from Acrocalymmaceae. Boeremia exigua (CBS 431.74) and Boeremia foveata (CBS 341.67) are used as the outgroup taxa. The dataset comprised 1997 characters after alignment including gaps (LSU=1308 bp and ITS=689 bp). The RAxML analysis of the combined dataset yielded a best scoring tree with a final ML optimization likelihood value of − 4737.006546. The matrix had 316 distinct alignment patterns, with 31.82% of undetermined characters or gaps. Estimated base frequencies were as follows: A=0.245559, C=0.218996, G=0.276710, T=0.258736; substitution rates: AC=1.502433, AG=1.688434, AT=1.833814, CG=0.473416, CT=4.863789, GT=1.000000; gamma distribution shape parameter
α=0.020000. The MP analysis resulted a single most parsimonious tree (TL=391, CI=0.831, RI=0.875, RC=0.727, HI=0.169). Bootstrap support values for MLBS and MPBS equal to or greater than 75% BYPP equal to or greater than 0.95 are given above the nodes. Ex-type strains are in bold and newly generated sequence is in blue