Fungalpedia – Note 3250, Pseudothailandiomyces
Pseudothailandiomyces S.N. Zhang, E.B.G. Jones & K.D. Hyde.
Citation when using this data: Zhang SN et al. 2024 – Fungalpedia.
Index Fungorum, Faceoffungi, MycoBank, GenBank, Fig 1.
Classification: Tirisporellaceae, Tirisporellales, Incertae sedis, Dothideomycetes, Pezizomycotina, Ascomycota, Fungi.
Etymology: The prefix pseudo- (Gr., false); “Pseudothailandiomyces” refers to its close affinity with the genus “Thailandiomyces”.
Saprobic on submerged petiole of mangrove palm. Sexual morph Ascomata superficial, solitary to gregarious, subglobose to globose, with a short to long ostiolar neck, base flattened, black, erumpent through the host plant epidermis, usually with ruptured host tissue around the ascomata. Ostiole periphysate. Peridium thick, melanized, in thin section visible as hyaline or pale brown inner layer with cells of elongate textura angularis, and outer layer with reddish brown cells of textura intricata to textura epidermoidea. Paraphyses present but deliquescent. Asci 8-spored, unitunicate, cylindrical, sessile. Ascospores overlapping biseriate, ellipsoidal to sub-cylindrical, hyaline to brown, 1-septate, constricted at the septum, guttulate, smooth-walled. Asexual morph Hyphomycetous, craspedodidymum-like. Conidiophores macronematous, mononematous. Conidiogenous cells integrated, terminal, enteroblastic, monophialidic. Conidia obovoid, oval or ellipsoidal, hyaline to brown, aseptate.
Notes: We introduce a new genus Pseudothailandiomyces, as in phylogenetic analyses it forms an independent branch and is distinct from other genera in Tirisporellaceae. The comparison of molecular data showed that 1.92% (16/833) nucleotide differences and 0.72% (6/833) gaps in the LSU gene region between Pseudothialandiomyces and Thailandiomyces, which is less than the difference between Pseudothailandiomyces and other genera. Morphologically, Pseudothialandiomyces resembles Thailandiomyces with a craspedodidymum-like asexual morph. However, it differs from the latter in ascospore morphology (ellipsoidal to sub-cylindrical vs. fusoid), color (hyaline to brown vs. hyaline), and appendages (without appendages vs. with bipolar spine-like appendages).
Type species: Pseudothailandiomyces nypae S.N. Zhang, E.B.G. Jones & K.D. Hyde.
Other accepted species: Species Fungorum – search Pseudothailandiomyces.
Figure 1 – Pseudothailandiomyces nypae (SNT108, holotype) a, b Ascomata on substrate. c Vertical section of an ascoma. d Peridium of ostiole. e Peridium side section. f Ostiole with periphyses. g–i Asci. j Ascus apex with a J- subapical ring. k Paraphyses (along with an ascospore in the same view). l–o Ascospores. p Germinating ascospore. q, r Colony on PDA, above (q), below (r). s Sporulation in culture. t–w Conidia. Scale bars: a = 1 mm; b = 500 μm; c = 200 μm; d–f = 50 μm; g–i = 20 μm; j–p, s–w = 10 μm.
Entry by
Sheng-Nan Zhang, School of Life Science and Technology, Center for Informational Biology, University of Electronic Science and Technology of China, Chengdu 611731, P.R. China., Department of Entomology and Plant Pathology, Faculty of Agriculture, Chiang Mai University, Chiang Mai 50200, Thailand., Center of Excellence in Fungal Research, Mae Fah Luang University, Chiang Rai 57100, Thailand.
Published online 18 September 2026