Fungalpedia – Note 3312, Agaricostilbomycetes
Agaricostilbomycetes R. Bauer, Begerow, J.P. Samp., M. Weiss & Oberw., Mycol. Progr. 5(1): 45 (2006).
Citation when using this data: Wijayawardene NN et al. 2024 – Fungalpedia.
Index Fungorum, Faceoffungi, MycoBank, GenBank, Fig 1.
Classification: Pucciniomycotina, Basidiomycota, Dikarya, Fungi.
Agaricostilbomycetes are a highly diverse class of fungi in terms of morphology and ecology. Currently, the class comprises one order, five families, and more than 70 species distributed over 13 genera (Aime et al. 2014; Wang et al. 2015c; Oberwinkler 2017; Begerow et al. 2018; He et al. 2019; Li et al. 2020; Cao et al. 2021). The monophyly of the class was recognised by various phylogenetic studies (Bauer et al. 2006; Aime et al. 2006; Wang et al. 2015c). These studies often recovered long terminal branches in this class, indicating large phylogenetic distances between the representatives. At the ulturastructural level, the class is characterised by septal pores with simple morphology and without associated microbodies, separation of nucleoplasmic spindle pole bodies, and metaphasic spindle pole bodies that occur intranuclearly (Bauer et al. 2006; Begerow et al. 2018). Most species are exclusively known as asexually reproducing yeast morphs, whereas a few species are characterised by a dimorphic lifecycle, alternating between a unicellular yeast morph and a multicellular filamentous morph in which sexual structures are developed. It is likely that all Agaricostilbomycetes are dimorphic organisms, and that the hyphal morph for most species remains to be discovered in natural or laboratory conditions. For example, Fonseca et al. (2000) reported the development of a hyphal morph with transversally septate basidia in Kondoa aeria and K. malvinella in culture conditions after several months of inoculation. Basidiomata are usually small and comprise stilboid (Chionosphaera, Crittendenia, Sterigmatomyces, Stilbum) and pustulate forms (Mycogloea spp). The studied dimorphic species in this class display a large diversity in the structures for sexual reproduction. Stilbum spp. develop transversally septate basidia producing statismospores. Chionosphaera spp. and Crittendenia spp. produce holobasidia with statismospores (Kirschner et al. 2001). Kondoa spp. produce transversally septate basidia producing ballistospores (Fonseca et al. 2000). Mycogloea spp. produce transversally septate basidia that become detached from the basidiogenous cell, after which sterigmata and ballistospores are formed (Bandoni 1998; Kirschner et al. 2003).
Life modes and distribution: Agaricostilbomycetes have been isolated from a large diversity of substrates in marine and terrestrial habitats. Yeast morphs are often considered to act as saprobes. Hyphal morphs were isolates from soil (Cystobasidiopsis nirenbergiae), palm litter (Sterigmatomyces spp.), lichens (Crittendenia spp.), and fruitbodies of other fungi (Bensingtonia spp. Kondoa spp.). Whether the fungicolous and lichenicolous species are parasites of their respective hosts remains unknown (Millanes et al. 2021). Haustorial cells are often seen as an indication of mycoparasitism and were reported from Stilbum vulgare and Kondoa myxariophila, but only in laboratory conditions (Seifert et al. 1992; Li et al. 2020).
Notes: Bauer et al. (2006) introduced the class Agaricostilbomycetes to accommodate two orders, Agaricostilbales Oberw. & R. Bauer and Spiculogloeales R. Bauer et al. However, Spiculogloeales was only represented by two representatives (Mycogloea sp. and Spiculogloea sp.), and the authors already suggested that in the future the clade should be separated into its own class (Bauer et al. 2006). Wang et al. (2015c) showed that the Sporobolomyces subbruneus clade clustered with Spiculogloea sp., and introduced the class Spiculogloeomycetes for this lineage.
Agaricostilbum species are presumed saprobic fungi on palm leaves that were isolated from various palm hosts. Oberwinkler (2017) critically discussed the suggested synonymy of Agaricostilbum palmicola and A. pulcherrimum that was proposed by Brady et al. (1984) without providing details to support the synonymy. Based on DNA sequence data, Wang et al. (2015c) combined A. pulcherrimum in the genus Sterigmatomyces. Oberwinkler (2017) emphasised that this genus is in need of reinvestigation, combining phylogenetic and morphological markers from a broad sampling of various palm hosts.
Mycogloea nipponica was shown to be the filamentous morph of Kurtzmannomyces sp. (Kirschner et al. 2003). Several other Kurtzmannomyces yeast species are known, as well as various Mycogloea species (Bandoni 1998). However, the overlap in data derived from these fungi is minimal, and many teleomorph-anamorph links remain to be discovered. Because of the lack of DNA sequence data, it remains unclear if all known Mycogloea species belong to Agaricostilbomycetes.
Type Order: Agaricostilbales Oberw. & R. Bauer, Sydowia 41: 240 (1989).
Type Family: Agaricostilbaceae Oberw. & R. Bauer, Sydowia 41: 240 (1989).
Type Genus: Agaricostilbum J.E. Wright, Mycologia 62(4): 679 (1970).
Type Species: Agaricostilbum palmicola J.E. Wright, Mycologia 62(4): 680 (1970).
Other accepted species: Species Fungorum – search Agaricostilbomycetes.
Figure 1 – Agaricostilbum palmicola. a Habit. b Conidiophore tip showing the emergence of conidia, and c Conidia × 2,800. d Branching of young conidiophore × 850. Scale bars: a = 1mm, b,c = 5 µm (redrawn from Wright 1970).
References
Bandoni RJ. 1998 – On some species of Mycogloea. Mycoscience 39 (1):31–36.
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