Coniothyrioides thailandica Wijes., M.S. Calabon, E.B.G Jones & K.D. Hyde, in Wijesinghe, Calabon, Xiao, Jones & Hyde, Stud. Fung. 9(no. 6): 11 (2023)

Index Fungorum number: IF 555050, MycoBank number: MB 555050, Facesoffungi number: FoF 13902

Etymology – The name reflects the county Thailand, from where the species was isolated.

Saprobic on a submerged and decaying woody substrate. Sexual morph: Undermined. Asexual morph: Coelomycetous. Conidiomata 150–200 µm high, 100–150 µm diam. (x̄ = 160 × 130 µm), pycnidial, semi-immersed, erumpent through the host substrate, globose to subglobose, solitary, scattered to aggregated, uni-loculate, ostiolate, covered by setae, rigid when dehydrated, black. Setae 3–5 µm wide, originating from the outermost layers of conidiomatal wall, divergent, brown, with hyaline apex, septate, smooth-walled, uniformly wide from base to apex. Conidiomatal wall 15–20 µm wide, equally thickened, composed of several layers, outermost layers dark brown to black, towards inside pale brown to hyaline cells of textura angularis, surrounded by setae. Conidiophores reduced to conidiogenous cells. Conidiogenous cells 4–5 µm long × 2.5–3.5 µm wide, lining the inner cavity, doliiform to subcylindrical, smooth-walled, hyaline, enteroblastic, phialidic conidiogenesis with periclinal thickening at the apex. Conidia 3–5 × 2.5–3 µm (x̄ = 4.5 × 2.7 µm, n = 20), solitary, ellipsoidal to obovoid, rounded at the apex, aseptate, initially hyaline, becoming pale to dark brown at maturity, smooth-walled, sometimes finely verruculose, with smaller guttules at young and indistinct at maturity.

Culture characteristics – On MEA, colony circular with a filamentous margin, reaching 40–45 mm diam. in 25 d at 25 °C, light gray from above, brown from center becoming light gray in the margin below, surface rough, dry, flat, with dense mycelia, edge filiform.

Material examined – Thailand, Pranburi Province, on a submerged decaying wood, 23 March 2021, Mark S. Calabon, SPAR26 (MFLU 22-0276, holotype), ex-type living cultures, MFLUCC 22-0193.

GenBank accession numbers – ITS = OQ023276, LSU = OQ023277, SSU = OQ025050.

Notes – Coniothyrioides thailandica sp. nov. shares morphological characters with other representatives in Coniothyriaceae in having pycnidial, globose, uni-locular conidioma with a central ostiole, peridial wall with the cells of textura angularis, and doliiform to subcylindrical conidiogenous cells, and phialidic conidiogenesis with a periclinal thickening at the apex. The synopsis of asexual morphological characters for the generic types of the family, including their hosts and localities, is presented in Table 3 (refer to Wijesinghe et al. 2023). Based on the presence of conidiomatal setae, our species (MFLU 22-0276) resembles Neoconiothyrium [24]. In addition, our species resembles Foliophoma camporesii (MFLU 17-1006) in having hyaline to brown and aseptate conidia but differs in having larger conidiomata (150–200 × 100–150 vs 40–47 × 40–69 µm) and the presence of setae on the wall (Table 3, refer to Wijesinghe et al. 2023). Phylogenetically, our strain (MFLUCC 22-0193) formed an independent lineage within Coniothyriaceae with 94% ML and 0.99 BI statistical support (Fig. 1). The base pair differences between our stain and the strains represent type species of other genera in Coniothyriaceae are listed (Table 4, refer to Wijesinghe et al. 2023). Thus, based on both morphology and phylogeny, we establish Coniothyrioides as a new genus in Coniothyriaceae, with C. thailandica as the type species.

Figure 1 – Coniothyrioides thailandica sp. nov. (MFLU 22-0276, holotype). (a) & (b) Appearance of conidiomata on a submerged decaying woody substrate. (c) Longitudinal section of conidioma. (d) Conidiomatal wall. (e) The appearance of setae. (f) & (g) Conidiogenous cells with developing conidia. (h) Conidia. Scale bars: a = 200 µm, b = 100 µm, c = 50 µm, d = 20 µm, e, h = 10 µm, f, g = 5 µm.