Fungalpedia – Note 3314, Classiculomycetes
Classiculomycetes 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.
Classiculomycetes were introduced by Bauer et al. (2006) to accommodate a clade with two species isolated from aquatic habitats, namely Classicula fluitans and Jaculispora submersa. More recently, Qiao et al. (2018) described a second Classicula species from China. The class comprises one order (Classiculales), one family (Classiculaceae), two genera and three species (Bauer et al. 2006; Begerow et al. 2018; He et al. 2019). At the ultrastructural level, the septal pores have a simple morphology, and are associated with microbodies (Bauer et al. 2003, 2006). All species were originally isolated a described as anamorphic fungi, with typical navicular conidia characterised by three or four setose appendages, clamped hyphae, and the presence of basally clamped haustorial cells. All three species are known from filamentous morphs only, no yeast budding is known. Naiadella fluitans was originally isolated as an anamorphic fungus from leaf litter in a freshwater stream in Canada (Marvanová and Bandoni 1987). Bauer et al. (2003) reported the production of the sexual state of Naiadella fluitans, which is characterised by transversally septate basidia producing ballistospores and for which the name Classicula fluitans was introduced. These basidia were only observed in pure culture after soaking the fungus in water. No basidiospore germination was observed (Bauer et al. 2003). Aime et al. (2018) called for the protection of the name Classicula, based on which the nomenclature of the higher taxa in the class is based.
Life modes and distribution: Classicula and Jaculispora were isolated from aquatic environments and are especially associated with leaf litter in freshwater habitats (Bauer et al. 2003). The conidia with broadly diverging setose branches in the three known species resemble those of other aquatic hyphomycetes and may be an adaptation to survival and dispersal in such environments (Ingold 1979). Also, the long and small basidiospores produced by Classicula fluitans could be an adaptation to water dispersal (Bauer et al. 2003). Plant host preferences have been tested for Jaculispora submersa, and suggest an affinity for oak leaves (Prokhorov and Bodyagin 2007). There are indications that Classicula and Jaculispora species are mycoparasites because of the presence of basally clamped haustorial cells. Such haustorial cells are known from many basidiomycetous mycoparasites, and along the contact surface between the haustorial cell and host cell one or more fusion pores are produced (Bauer 2004; Bauer et al. 2006; Schoutteten et al. 2023). However, the haustorial cells in C. fluitans were only observed to attach to hyphae of their own mycelium, which was interpreted as self-parasitism, but no fusion pores were observed (Bauer et al. 2003). It remains unclear if these structures are also formed in natural conditions, and if, and with which other fungi mycoparasitic associations are established.
Note: The species diversity of this class may be higher than currently known because freshwater ecosystems have always been under-sampled niches for fungi (Cao et al. 2021). Generally, Jaculispora submersa is distributed in aquatic environments in Jamaica (Hudson and Ingold 1960) and is also found in Europe, Great Britain, Canada, North America (Cole and Kendrick 1981), and India (Borse et al. 2015). Classicula fluitans found in Canada, Czechia, and India (Borse et al. 2015). Classicula sinensis was only recorded in China (Qiao et al. 2018).
Type order: Classiculales R. Bauer, Begerow, Oberw. & Marvanová, Mycologia 95(4): 763 (2003).
Type family: Classiculaceae R. Bauer, Begerow, Oberw. & Marvanová, Mycologia 95(4): 763 (2003).
Type genus: Classicula R. Bauer, Begerow, Oberw. & Marvanová, Mycologia 95(4): 757 (2003).
Type species: Classicula fluitans R. Bauer, Begerow, Oberw. & Marvanová, Mycologia 95(4): 757 (2003).
Other accepted species: Species Fungorum – search Classiculomycetes.
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.
Borse BD, Patil VR, Nemade LC, Chaudhari SA et al. 2015 – Freshwater Basidiomycetes from India. In: Patil VR (ed) Resrach on Freshwter fungi. Lulu Publications. USA.
Cole GT, Kendrick B. 1981 – Biology of Conidial Fungi vol 1. Academic Press, pp 504.
Ingold CT. 1979 – Advances in the study of so-called aquatic hyphomycetes. Am J Bot 66:218–226.
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