Fungalpedia – Note 3309, Bartheletiomycetes
Bartheletiomycetes Thines, Mycological Progress 17 (3): 340 (2017).
Citation when using this data: Wijayawardene NN et al. 2024 – Fungalpedia.
Index Fungorum, Faceoffungi, MycoBank, GenBank, Fig 1b.
Classification: Agaricomycotina, Basidiomycota, Dikarya, Fungi.
Asexual morph: The sori produce copious conidia (slimy, hyaline 1-celled), which germinate readily to infect other newly fallen leaves. Conidiophores branched, hyaline, finely verruculose in the apical parts, originating from a ± compact base of irregularly interwoven, hyaline to pale brown intramatrical hyphae. Conidiogenesis holoblastic. Conidiogenous cells are mostly long, terminal, or intercalary with one or two conidiogenous branches, unilocal with percurrent proliferation and rather dense annellations, and/or multilocal with distichous sympodial proliferation and densely stacked secession scars. Conidia hyaline, one-celled, straight, cylindrical-bacilliform or sometimes slightly broader below the middle with a short attenuate base and minutely truncate scar, uninucleate with the nuclear area in the middle, with minute guttules, finely verruculose. The conidiophores are soon replaced by teliospores originating from the same basal cushion of intramatrical hyphae (Scheuer et al. 2008). Sexual morph: thick-walled, dark brown Teliospores either single, immersed in the leaf tissues and ± evenly dispersed (most conspicuous in the epidermis), or conglutinated in compact, erumpent, and finally ± superficial telia. Telia (similar to those of rust fungi) are single or arranged in ± circular groups. Telia often develop from conidial sori, hemispherical or cushion-like to ±spherical. After a year of dormancy, teliospores germinate with stipitate, longitudinally septate, statismosporic phragmobasidia and produce basidiospores on each sporogenous locus (Scheuer et al. 2008).
Life modes and distribution: Bartheletia paradoxa is apparently saprotrophic rather than endophyte, strictly host-specific and widely distributed fungal companion of Ginkgo biloba. Most probably, just like its host plant, the fungus is also a living fossil (Scheuer et al. 2008). Its biology is unclear. Kirschner and Okuda (2013) showed that the fungus is a pioneer colonizer in the initial stage of decomposition of Ginkgo litter. According to available information, although Ginkgo is grown worldwide, the global distribution of B. paradoxa is uneven. The species are generally distributed in Europe (Austria, Czech Republic, Denmark, France, Germany, Sweden, Netherlands, and the United Kingdom), Russia, Ukraine, and Asia (Japan and Korea) (Hayova and Tykhonenko 2017).
Note: The family Bartheletiaceae was proposed to accommodate B. paradoxa, which was discovered on ginkgo leaf litter and remained unknown for a long time (Scheuer et al. 2008). The first valid information on this fungus was included only by Scheuer et al. 2008 (Hayova and Tykhonenko 2017). The position of B. paradoxa was not resolved in the initial nrSSU DNA sequence analysis, but Mishra et al. (2018) took a more phylogenetic approach using a large set of conserved genes and offered a perfect solution. The new study used 67 highly conserved orthologous loci for network analysis. New data excluding negative genes strongly (but not conclusively) support that this organism is at the base of the Agaricomycetes and is the sister of all other members of the sub-phylum and separate from the Ustilaginomycotina and Pucciniomycotina, which together create a sister group to the whole of the Agaricomycotina. The new class and order Bartheletiomycetes and Bartheletiales, were introduced by Mishra et al. (2018).
According to Wijayawardene et al. (2020a), the class Bartheletiomycetes consists of a single order Bartheletiales, single family Bartheletiaceae, and single genus Bartheletia. B. paradoxa is the only species within this genus (Scheuer et al. 2008). Bartheletiomycetes paradoxa reproduces sexually only on ginkgo leaves and can survive in some tissues of ginkgo trees as an asymptomatic disease (Scheuer et al. 2008).
Type Order: Bartheletiales Thines, Mycological Progress 17 (3): 340 (2017).
Type Family: Bartheletiaceae R. Bauer, Scheuer, M. Lutz & Grube, in Scheuer, Bauer, Lutz, Stabentheiner, Melnik & Grube, Mycol. Res. 111(11): 1269 (2008).
Type Genus: Bartheletia G. Arnaud ex Scheuer, R. Bauer, M. Lutz, Stabenth., Melnik & Grube, Mycol. Res. 111(11): 1269 (2008).
Type Species: Bartheletia paradoxa G. Arnaud ex Scheuer, R. Bauer, M. Lutz, Stabenth., Melnik & Grube, Mycol. Res. 112(11): 1269 (2008).
Other accepted species: Species Fungorum – search Bartheletiomycetes.
Figure 1 – Different taxa of Basidiomycota. a Agaricomycetes (Amanita hemibapha). b Bartheletiomycetes (Bartheletia paradoxa). c Cystobasidiomycetes (Cyphobasidium), white arrow shows the fruiting bodies. d Dacrymycetes (Dacryomyces spathularia). e Exobasidiomycetes (Exobasidium ferrugineae). f Malasseziomycetes (Malassezia); g Microbotryomycetes (Microbotrium). h Physodermatomycetes (Physoderma menyanthis). i Pucciniomycetes (Puccinia). j Tremellomycetes (Tremella fusiformis). k Tritirachiomycetes (Tritirachium oryzae). l Ustilaginomycetes (Mycosystema maydis). m Wallemiomycetes (Wallemia sebi). Photo credits: Figure a: Stephen Axford, Figures B-M: iNaturalist (The photos have been used under the CC BY-NC 4.0 non-commercial use license).
References
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 29 September 2026