Fungalpedia – Note 568, Mixia
Mixia C.L. Kramer
Citation when using this data: Zhang et al. 2025 (in prep.) – Fungalpedia, Basidiomycota.
Index Fungorum, Facesoffungi, MycoBank, GenBank, Fig. 1
Classification: Mixiaceae, Mixiales, Incertae sedis, Mixiomycetes, Pucciniomycotina, Basidiomycota, Fungi
Mixia was introduced by Kramer (1958) to accommodate a new combination, M. osmundae, which was first described as Taphrina osmundae. Mixia was previously placed in the families Protomycetaceae or Mixiaceae within Ascomycota (Kramer 1958, 1987). Later, Mixia was placed in Mixiomycetes within Basidiomycota (Schell et al. 2011, Aime et al. 2014, Toome et al. 2014, Wang et al. 2015), and was considered to occupy a rather basal position among basidiomycetes based on the phylogeny and morphological characters (Nishida et al. 1995; Wang et al. 2015; Kirschner et al. 2019). The latest studies place the genus in Mixiaceae, Mixiales, Mixiomycetes (He et al. 2024; Hyde et al 2024c) Currently, only one species, M. osmundae, is accepted in this genus. It is an intracellular parasite on Osmunda species, including O. cinnamomea, O. japonica, and O. regalis var. japonica, found in China, Japan, and the United States (Sawada 1929; Kramer 1958; Toome et al. 2014). Mixia osmundae is a unique fungus due to its host preference for Osmunda spp. (Osmundaceae), its sporogenous structure, and its manner of spore formation. It is characterized by having small, yellow or brown lesions that develop a powdery white layer of spores; exogenous and simultaneous spores are produced on the surface of a large sac-like cell that forms from an enlarged swelling within the host epidermal cell wall (Sawada 1929; Mix 1947; Sugiyama and Katumoto 2008; Toome et al. 2014). Studies on the genome of Mixia osmundae have been provided (Nishida et al. 2011; Toome et al. 2014). The peculiar and enigmatic genus Mixia has been intensively studied, and is considered a “primitive” fungus that grows on “primitive” hosts (Nishida et al. 2012; Sugiyama et al. 2018). A systematic review of Mixia osmundae, including its historical background, distributional data, phylogeny, and phylogenomics was provided by Sugiyama et al. (2018).
= Phytoceratiomyxa Sawada, Trans. Nat. Hist. Soc. Formosa 19: 31 (1929).
Type species: Mixia osmundae (Nishida) C.L. Kramer.
≡ Taphrina osmundae Nishida.
≡ Phytoceratiomyxa osmundae Sawada, Transactions of the Natural History Society of Formosa 19: 31 (1929).
Other accepted species: Species Fungorum – search Mixia.
Figure 1 – Mixia osmundae. a Early stage of fructification formation. b Formation of endogenous spores. c Formation of endogenous spores and microspores. d Fructification after endogenous spore abscission. e Endogenous spores. f Microspores. g Microspore germination from endogenous spores. h Sporogenous cells after endogenous spore abscission. i Early stage of endogenous spore formation. j Formation of endogenous spores. k Fructification after spore abscission. Redrawn from Sugiyama and Katumoto (2008).
References
Hyde KD, et al. 2024c – The 2024 outline of fungi and fungus-like taxa. Mycosphere (in press).
Kramer C 1958 – A new genus in the Protomycetaceae. Mycologia 50:916–926.
Kramer C 1987 – The Taphrinales. Stud Mycol 30:151–166.
Mix AJ 1947 – Taphrina osmundae Nishida and Taphrina higginsii sp. nov. Mycologia 39:71–76.
Sawada K 1929 – Fungi from Taiwan (no. 27). Trans Nat Hist Soc Formosa 19:31–39.
Entry by
Jing-Yi Zhang, School of Food and Pharmaceutical Engineering, Guizhou Institute of Technology, Guiyang, 550025, People’s Republic of China, Center of Excellence in Fungal Research, Mae Fah Luang University, Chiang Rai, 57100, Thailand, School of Science, Mae Fah Luang University, Chiang Rai, 57100, Thailand, Guizhou Key Laboratory of Agricultural Microbiology, Guizhou Academy of Agricultural Sciences, Guiyang, 550009, People’s Republic of China.
Published online 11 June 2025