Fungalpedia – Note 3316, Cystobasidiomycetes
Cystobasidiomycetes R. Bauer, Begerow, J.P. Samp., M. Weiss & Oberw., Mycol. Progr. 5(1): 46 (2006).
Citation when using this data: Wijayawardene NN et al. 2024 – Fungalpedia.
Index Fungorum, Faceoffungi, MycoBank, GenBank.
Classification: Pucciniomycotina, Basidiomycota, Dikarya, Fungi.
The class Cystobasidiomycetes was proposed by Bauer et al. (2006) and comprises six orders (Buckleyzymales, Cyphobasidiales, Cystobasidiales, Erythrobasidiales, Naohideales, and Sakagushiales), eight families (Buckleyzymaceae, Cyphobasidiaceae, Cystobasidiaceae, Erythrobasidiaceae, Microsporomycetaceae, Naohideaceae, Sakaguchiaceae, and Symmetrosporaceae), 16 genera, and over 100 species (Wang et al. 2015c; Begerow et al. 2018; He et al. 2019; Li et al. 2020). At the ultrastructural level, Cystobasidiomycetes have simple septal pores which are surrounded by cylindrical organelles with a reticulate surface, called cystosomes.
The cystosome seems to be synapomorphic for this class, but they were only reported from a few dimorphic representatives. However, the cystosome was not found in the septal pores of Naohideales. Cell walls of Cystobasidiomycetes lack fucose in the sugar composition (Takashima et al. 2000; Bauer et al. 2006). The vast majority of Cystobasidiomycetes is exclusively known from a yeast morph, although it is likely that most of them have dimorphic life cycles. The filamentous morphs of Cystobasidiomycetes are usually characterised by transversally septate basidia, often subtended by a thick-walled probasidium. Reproductive structures in Bannoa and Erythrobasidium are single-celled, but it remains unclear whether it concerns conidiophores or real basidia (Bauer et al. 2006; Oberwinkler 2017; Begerow et al. 2018). Dimorphic species are found in Bannoa, Cystobasidium, Naohidea, Occultifur, and Sakaguchia. Several species were assigned to genera in Cystobasidiomycetes based on morphological resemblances, such as the (thick-walled) probasidium in combination with transversally septate basidia. However, their assignment to this class remains to be confirmed by molecular data. Basidiospore germination is either with hyphae, secondary spore formation, or yeast budding. Yeast colonies are usually orange-pinkish pigmented, except in Nahoideale which is characterised by whitish yeast colonies.
Life modes and distribution: Cystobasidiomycetes have been discovered and isolated from various substrates in terrestrial and marine habitats, including air, freshwater aquatic environments, soil, beetle guts, mammals, sea sponges, other fungi, and plants (Libkind et al. 2010, Oberwinkler 2017, Begerow et al. 2018). Several species in this class are (intrahymenial) mycoparasites characterised by haustorial cells and interact with nanometer fusionpores, establishing cytoplasmic contact between host and mycoparasite (Bauer 2004; Bauer et al. 2006; Oberwinkler 2017). Occultifur and Cyphobasidium mycoparasites produce typical tremelloid haustorial cells, the haustoria of Naohidea sebacea invaginates host cells. Cyphobasidium species are found in association with lichen thalli, but it is unclear what the nature of this association is (Millanes et al. 2016, Diederich et al. 2022).
Notes: The class Cystobasidiomycetes was introduced by Bauer et al. (2006) to include fungi without fucose in their cell walls, and spindle pole bodies that are intranuclear during the metaphase.
Type order: Cystobasidiales R. Bauer, Begerow, J.P. Samp., M. Weiss & Oberw., Mycol. Progr. 5(1): 46 (2006).
Type family: Cystobasidiaceae Gäum., Vergl. Morph. Pilze (Jena): 411 (1926).
Type genus: Cystobasidium (Lagerh.) Neuhoff, Bot. Arch. 8: 272 (1924).
Type species: Cystobasidium lasioboli (Lagerh.) Neuhoff, Bot. Arch.: 273 (1924).
Other accepted species: Species Fungorum – search Cystobasidiomycetes.
References
Begerow D, McTaggart A, Agerer R. 2018 – 1/3 Basidiomycota and Entorrhizomycota In: Frey, W. (Ed.) A. Engler’s Syllabus der Pflanzenfamilien. Germany: Bontraeger Science Publishers.
Oberwinkler F. 2017 – Yeasts in Pucciniomycotina. Mycol Prog 16:831–856.
Entry by
Nalin N. Wijayawardene, Center for Yunnan Plateau Biological Resources Protection and Utilization, College of Biological Resource and Food Engineering, Qujing Normal University, Qujing, Yunnan 655011, P.R. China, Tropical Microbiology Research Foundation, 96/N/10, Meemanagoda Road, 10230 Pannipitiya, Sri Lanka, Department of Bioprocess Technology, Faculty of Technology, Rajarata University, Sri Lanka
Published online 2 October 2026