Fungalpedia – Note 3284, Laboulbeniomycetes

 

Laboulbeniomycetes Engler & Prantl, Nat. Pflanzenfam., Teil. I (Leipzig) 1: vi (1897).

Citation when using this data: Wijayawardene NN et al. 2024 – Fungalpedia.

Index Fungorum, Faceoffungi, MycoBank, GenBank, Fig 1.

Classification: Pezizomycotina, Ascomycota, Dikarya, Fungi.

Notes: Laboulbeniomycetes is a class of microscopic fungi within Ascomycota exhibiting an obligate association with arthropods. Three named (Laboulbeniales, Herpomycetales and Pyxidiophorales) and two unnamed (Chantransiopsis and Laboulbeniopsis) clades are currently accepted (Haelewaters et al. 2021a). However, the circumscription of these clades has been impeded by numerous taxonomic and phylogenetic misunderstandings and misinterpretations, resulting in a turbulent taxonomic history (fide Haelewaters et al. 2021b). Initially mistaken for parasitic worms or red algal relatives, there was no consensus among biologists and mycologists regarding the fungal nature of these organisms during the 20th century, mainly due to the lack of “typical” fungal characters. Charles P. Robin (1821–1885) was the first one to recognize Laboulbeniomycetes as fungi, alongside Roland Thaxter (1891–1931) who later considered them to be ascomycetes (Blackwell et al. 2020). Thaxter’s efforts led to the description of over half of the currently known diversity of Laboulbeniomycetes, inevitably based on morphological characters (e.g. perithecium morphology or asci development).

Since Engler (1898) erected the class Laboulbeniomycetes, the accumulation of empirical data and the development of molecular-based tools considerably improved our understanding of life history traits and phylogenetic relationships within this group. The class was for the first time confirmed by molecular data by Weir and Blackwell (2001) and while molecular-based studies show clear advantages over field-based observations (Cazabonne et al. 2022), numerous phylogenetic relationships within Laboulbeniomycetes remain to be elucidated. Goldmann and Weir (2018) demonstrated that Laboulbeniomycetes is a monophyletic group within Ascomycota, closely related to Sordariomycetes, confirming the previous placement of the Laboulbeniales–Pyxidiophora clade (Weir and Blackwell 2001). The uncertain placement of the genus Herpomyces was resolved by Haelewaters et al. (2019) by the introduction of the order Herpomycetales based on molecular phylogenetic, morphological, developmental, and host usage data. Despite those recently undertaken efforts, deeper nodes remain unresolved and the sister group of Laboulbeniomycetes is yet to be discovered (Blackwell et al. 2020). Fossil records for Laboulbeniomycetes are limited to Columnomyces electri from Dominican amber (Perreau et al. 2021) and Stigmatomyces succini from Bitterfeld amber (Rossi et al. 2005).

Type order: Laboulbeniales Lindau, in Engler & Prantl, Nat. Pflanzenfam., Teil. I (Leipzig) 1(1): 47 (1897).

Type family: Laboulbeniaceae G. Winter [as ‘Laboulbenieae’], Rabenh. Krypt.-Fl., Edn 2 (Leipzig) 1.2: 918 (1886).

Type genus: Laboulbenia Mont. & C.P. Robin, in Robin, Histoire naturelle des Vegetaux Parasites (Paris): 622 (1853).

Type species: Laboulbenia rougetii Mont. & C.P. Robin, in Robin, Histoire naturelle des Vegetaux Parasites (Paris): 622 (1853).

Other accepted species: Species Fungorum – search Laboulbeniomycetes.

 

Figure 1 – Laboulbeniomycetes, including (a-l) Laboulbeniales, (m-n) Herpomycetales, and (o-p) Pyxidiophorales. a Stigmatomyces majewskii. b Teratomyces actobii. c Rhachomyces anophthalmi. d Laboulbenia notiophili. e Dimeromyces rugosus. f Laboulbenia anisodactylus. g Arthrorhynchus eucampsipodae. h Gloeandromuces cusucoensis. i Laboulbenia oioveliicola. j Haplomyces texanus. k Hesperomyces harmoniae. l Gloeandromyces plesiosaurus f. plesiosaurus. m Herpomyces stylopygae. n Herpomyces shelfordellae. o Thaxteriola sp. p Pyxidiophora bialowiezensis. Scale bars: a, c, d, h, l-o = 50 µm; b, e, g, j, k, p = 100 µm; f = 10 µm; i = 20 µm. Photos: Danny Haelewaters; drawings: Jingyu Liu. 

 

References

Blackwell M, Haelewaters D, Pfister DH. 2020 – Laboulbeniomycetes: Evolution, natural history, and Thaxter’s final word. Mycologia 112(6):1048–1059.

Cazabonne J, Bartrop L, Dierickx G, Gafforov Y et al. 2022 – Molecular-based diversity studies and field surveys are not mutually exclusive: On the importance of integrated methodologies in mycological research. Front Fungal Biol 3:860777.

Goldmann L, Weir A. 2018 – Molecular phylogeny of the Laboulbeniomycetes (Ascomycota). Fungal Biol 122(2–3):87–100.

Haelewaters D, Blackwell M, Pfister DH. 2021a – Laboulbeniomycetes: intimate fungal associates of arthropods. Annu Rev Entomol 66:257–276.

Haelewaters D, Gorczak M, Kaishian P, DeKesel A, Blackwell M. 2021b – Laboulbeniomycetes, enigmatic fungi with a turbulent taxonomic history. In: Zaragoza O, Casadevall A (eds) Encyclopedia of mycology, vol 1. Elsevier, Amsterdam, pp 263–283.

Haelewaters D, Pfliegler WP, Gorczak M, Pfister DH et al. 2019 – Birth of an order: comprehensive molecular phylogenetic study excludes Herpomyces (Fungi, Laboulbeniomycetes) from Laboulbeniales. Mol Phylogenet Evol 133:286–301.

Weir A, Blackwell M. 2001 – Molecular data support the Laboulbeniales as a separate class of Ascomycota, Laboulbeniomycetes. Mycol Res 105(10):1182–1190.

 

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 25 September 2026

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