Fungalpedia – Note 2814, Ascosphaeraceae
Ascosphaeraceae. L.S. Olive & Spiltoir.
Citation when using this data: Kandemir H et al. 2022 – Fungalpedia.
Index Fungorum, Facesoffungi, MycoBank, GenBank
Classification: Ascosphaerales, Eurotiomycetidae, Eurotiomycetes, Pezizomycotina, Ascomycota, Fungi
The family Synascomycetaceae was proposed by Varitchak (1933) to describe fungi that have a sexual reproduction organ called the synascus, i.e., a single large vesicle with an acellular membranous peridium containing masses of “endospores” (spore balls). Since the fungi have reduced gametangia, Pericystis was concluded to be related to Plectascales and primitive Ascomycetes (Bessey 1950; Spiltoir and Olive 1955; Berbee and Taylor 1992; Geiser et al. 2006).
The name Pericystis was changed to Ascosphaera by Spiltoir and Olive (1955) because it was already in use for red algae (Pericystis Agardh 1847). Although the authors reclassified the genus and designated Ascosphaera apis as the type species, no type material was indicated. Ascosphaera was later reclassified in the family Ascosphaeraceae in the order Ascosphaerales (Gäumann 1964; invalid, ICBN Art. 37) and validated by Benny and Kimbrough (1980). Subsequently, Ascosphaera, Bettsia (Skou 1972) and Arrhenosphaera (Stejskal 1974) were included in the family. Arrhenosphaera, represented by the type species Arrhenosphaera craneae, was isolated from pollen and larvae in a comb of Apis mellifera in Venezuela (Stejskal 1974). However, no type was indicated, and the studied material was not known to be preserved; therefore, this name is considered doubtful.
Although Bettsia also produces spore cysts and shares the same niche as saprophytic Ascosphaera species (Skou 1972; Wynns 2015), it is found in Leotiomycetes, phylogenetically far from Ascosphaera (Pitt et al. 2013). Currently, Ascosphaeraceae is classified in Onygenales as a monophyletic family with the single genus Ascosphaera, and it is described with spore cysts with a double-layered wall and spore balls formed by groups of asci covered by a single membrane (Wynns et al. 2013).
Ascosphaeraceae comprises a group of fungi with a very specific ecology. Members of the family have thus far only been isolated from pollen, bee larvae/cadavers or nest cells. They can also grow in habitats related to other pollenivorous insects and have a high sugar content (Wynns et al. 2013). Only Ascosphaera atra, a solitary bee-related saprobe, has been isolated from grass silage, apparently outside the bee habitat (Skou 1986). Some species are bee pathogens. Ascosphaera apis and A. aggregata are of special interest because of their aetiologies of chalkbrood disease in economically important bee species (Aronstein and Murray 2010; Pitts-Singer and Cane 2011). Available ecological data in this study showed that most Ascosphaera species are associated with solitary bees in the Megachilidae family (n = 24/28) rather than with economically important social bees. Megachilidae have a worldwide distribution, which is matched by the widely distributed family Ascosphaeraceae (Marinho et al. 2018; Wynns et al. 2013).
The presence of simple sac-like fruitbodies is a common feature among bee-related fungi and is shared by Ascosphaera (Onygenales; Spiltoir and Olive 1955), Bettsia (Leotiales; Wynns 2015) and Eremascus (Onygenales; Gueidan et al. 2008; Wijayawardene et al. 2017; Wynns 2015). This characteristic seems to have emerged more than once in the course of evolution and may have an ecological adaptation to this specific habitat and dispersion of propagules (Wynns 2015). In contrast to Ascosphaera and Bettsia, Eremascus is described with completely naked asci (Wynns 2015). Rudimentary development or near-absence of gymnothecia has also been observed in other onygenalean genera, such as Narasimhella and Pseudoarachniotus (von Arx 1986; Orr et al. 1977a; de Hoog et al. 2020).
In the present study, Chrysosporium alvearium Liu & Cai (Zhao et al. 2018) (ex-type culture: LC11684), originating from hive-stored pollen, was also found to be a member of the Onygenales and has been reclassified above in Keratinophyton.
Type genus: Ascosphaera L.S. Olive & Spiltoir, in Spiltoir & Olive, Mycologia 47(2): 242 (1955).
Other accepted species: Species Fungorum – search Ascosphaeraceae.
References
Benny GL, Kimbrough JW 1980 – A synopsis of the orders and families of Plectomycetes with keys to genera. Mycotaxon 12(1):1–91.
Bessey EA 1950 – Morphology and taxonomy of fungi. The Blakiston Company, Toronto.
de Hoog GS, Guarro J, Gené J, Ahmed S, Al‑Hatmi AMS, Figueras MJ, Vitale RG 2020 – Atlas of Clinical Fungi: the ultimate bench tool for diagnostics, 4th edition. Foundation Atlas of Clinical Fungi, Hilversum, The Netherlands.
Gäumann E 1964 – Die Pilze: Grundzüge ihrer Entwicklungsgeschichte und Morphologie. Birkhäuser, Basel.
Orr GF 1977a – New Gymnoascaceae. Mycotaxon 6(1):33–42.
Skou JP 1972 – Ascosphaerales. Friesia 10(1–2):1–24.
Skou JP 1986 – Notes on the habitats, morphology and taxonomy of spore cyst fungi. Apimondia 30:260–264.
Varitchak B 1933 – Deuxième contribution à l’étude du développement des Ascomycetes. L’évolution nucléaire dans le sac sporifère de Pericystis apis Maassen et sa signification pour la phylogénie des Ascomycetes. Le Botaniste 25:343–391.
von Arx JA 1986 – The Ascomycete genus Gymnoascus. Persoonia 13:173–183.
Entry by
Hazal Kandemir, Center of Expertise in Mycology, Radboud University Medical Center/Canisius Wilhelmina Hospital, Nijmegen, The Netherlands, Division of Medical Mycology, Faculty of Medicine, University of Cukurova, Adana, Turkey
Published online 25 June 2026