Coniothyrioides Wijes., M.S. Calabon, E.B.G. Jones & K.D. Hyde, in Wijesinghe, Calabon, Xiao, Jones & Hyde, Stud. Fung.9(no. 6): 10 (2023)

Index Fungorum number: IF 555045, MycoBank number: MB 555045, Facesoffungi number: FoF 13901

Etymology – Resembling Coniothyrium taxa

Saprobic on a submerged decaying wood in salt marsh ecosystems. Sexual morph: Undermined. Asexual morph: Coelomycetous. Forming conspicuous, round to irregular, black pycnidia. Conidiomata semi-immersed, erumpent through the host substrate, globose to subglobose, solitary, scattered to aggregated, uni-loculate, ostiolate, covered in setae, rigid when dehydrated, black. Setae originated from the outermost layers of conidiomatal wall, divergent, brown, with hyaline apex, septate, smooth-walled, uniformly wide from base to apex. Conidiomatal wall composed of several layers, from outer to inner layers black, dark brown, pale brown to hyaline cells of textura angularis. Conidiophores reduced to conidiogenous cells. Conidiogenous cells lining the inner cavity, doliiform to subcylindrical, smooth-walled, hyaline, enteroblastic, phialidic conidiogenesis with periclinal thickening at the apex. Conidia 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. (refer to Wijesinghe et al. 2023)

Type species – Coniothyrioides thailandica

Note – Coniothyrioides gen. nov. is a monotypic genus associated with decaying woody substrates in salt marsh habitats in central Thailand. This genus is characterized by having pycnidial conidiomata with the cells of textura angularis wall surrounded by distinct setae, doliiform to subcylindrical, hyaline conidiogenous cells, and ellipsoidal to obovoid, aseptate and hyaline to brown conidia. Based on some conidial characteristics, such as aseptate, hyaline to brown conidia, the genus shares similar morphologies to coniothyrium-like taxa [19], by ellipsoidal to subcylindrical conidia sharing similar characteristics to Coniothyrium and Neoconiothyrium [9,16,20,24]. However, other accepted genera in Coniothyriaceae differ from this genus in conidial morphologies: Foliophoma has only hyaline conidia except for F. camporesii D. Pem & K.D. Hyde; Hazslinszkyomyces has muriformly septate conidia [27]; Ochrocladosporium has cladosporium-like conidia [35].

Moreover, phylogenetically Coniothyrioides forms a distinct lineage within Coniothyriaceae (Fig. 1). Coniothyrium carteri (Gruyter & Boerema) Verkley & Gruyter (LG1401_MS6E) was the closest species based on BLAST result of ITS (94.33% similarity) and C. telephii (Allesch.) Verkley & Gruyter (UTHSC:DI16-189) was the closest species LSU sequence data (99.31% similarity) and sequences are lacking for SSU in the GenBank. The genus is known from its asexual morph and the sexual morphology was not observed. In our phylogenetic analyses, Foliophoma species were grouped outside of Coniothyriaceae with closer to Libertasomycetaceae and Pleosporaceae species. Foliophoma was introduced by Crous & Groenewald[27] to accommodate F. fallens (Sacc.) Crous, in Coniothyriaceae based on the parsimony analyses of single LSU and ITS sequence data. Foliophoma camporesii was later introduced based on morphology and maximum likelihood analyses of LSU-SSU- ITS sequence data by Hyde et al.[25]. Based on morphology, Foliophoma species share similar characteristics to the species of Coniothyriaceae in having dark brown conidiomata, conidial wall with textura angularis cells, phialidic conidiogenesis sometimes with periclinal thickening or percurrent proliferation, and mainly ellipsoidal shaped conidia. However, the type species of the genus, F. fallens differs from other Coniothyriaceae taxa in having eustromatic conidiomata. Based on this taxonomic uncertainty, more fresh collections with additional coding genes are required to clarify the accurate placement of Foliophoma.

Figure 1 – Phylogram generated from maximum likelihood analysis based on combined LSU, SSU, and ITS sequenced data. Fifty-eight strains were included in the combined sequence analyses, which comprised 2251 characters with gaps (LSU = 800, SSU = 948, ITS = 503). Single gene analyses were also performed, and topology and clade stability were compared from the combined gene analyses. Ascochyta pisi Lib. (CBS 126.54) and Didymella azollae E. Shams, F. Dehghanizadeh, A. Pordel & M. Javan-Nikkhah (A1) were used as the outgroup taxa. The final ML optimization likelihood is -10163.644. The matrix included 494 distinct alignment patterns, including undetermined characters. Estimated base frequencies were obtained as follows: A = 0.245, C = 0.219, G = 0.274, T= 0.262; substitution rates AC = 2.73290, AG = 3.93954, AT = 2.73290, CG = 1.0, CT = 7.93321, GT = 1.0 and the gamma distribution shape parameter α = 0.439534. Bootstrap support values for ML (first set) equal to or greater than 75% and BYPP equal to or greater than 0.95 are given above or below the nodes. The strains from the current study are in red bold and the type strains are in black bold. The scale bar represents the expected number of nucleotide substitutions per site