Fungalpedia – Note 3286, Leotiomycetes

 

Leotiomycetes O.E. Erikss. & Winka, Myconet 1(1): 7 (1997).

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

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

Classification: Pezizomycotina, Ascomycota, Dikarya, Fungi.

Notes: Eriksson and Winka (1997) erected the class Leotiomycetes to classify ascomycetes with inoperculate asci, which include the morphological group of the inoperculate discomycetes. Eriksson (2005) excluded Geoglossaceae and added Pseudeurotiaceae to the class. Later, Wang et al. (2006) recognized the following higher taxa: Cyttariales, Erysiphales, Helotiales, Rhytismatales, Thelebolales, Myxotrichaceae, and Pseudeurotiaceae. Rossman et al. (2004) determined a close relationship between Chaetomella and Pilidium within Leotiomycetes. Chaetomellaceae was erected to accommodate the two genera Chaetomella and Pilidium (Baral et al. 2015) and later recognized as an ordinal-level clade by Crous et al. (2017). Using genomic data, Johnston et al. (2019) recognized Chaetomellales, Helotiales, Leotiales, Marthamycetales, Phacidiales, Rhytismatales, and Thelebolales. Recent ordinal-level additions include: Lauriomycetales (Hernández-Restrepo et al. 2017; Haelewaters et al. 2021c), Lichinodiales (Prieto et al. 2019), Micraspidales (Quijada et al. 2020), and Umbellidiales (Barreto et al. 2023). Haelewaters et al. (2021c) formally recognized Cyttariales and Erysiphales as family-level clades in Helotiales, and Lichinodiales as a family-level clade in Leotiales.

Over time, the following trends can be observed in the class: (1) in general, some genera have been studied significantly more than others. For example, the type genus Leotia has not received any taxonomic additions in over forty years (Otani 1982). (2) Many species and genera have frequently changed placement both among different higher taxa and between taxonomic levels (in both directions). A consequence of this has been an expansive definition of the now massive order Helotiales. (3) The class has been plagued by systematic inconsistencies among different studies (Quandt and Haelewaters 2021). Currently, the following orders are recognized: Chaetomellales, Helotiales, Lahmiales, Lauriomycetales, Leotiales, Marthamycetales, Medeolariales, Micraspidales, Phacidiales, Rhytismatales, Thelebolales, and Umbellidiales. 

Phylogenetic relationships within Leotiomycetes

The classification system and taxonomy of Leotiomycetes were traditionally based on morphology, in particular sexual and asexual diagnostic characteristics. However, morphologically defined taxa grouped in erected genera, families, and orders are often not supported by molecular phylogenies (e.g., Quijada et al. 2018; Ekanayaka et al. 2019; Johnston et al. 2019; Haelewaters et al. 2021c; Quandt and Haelewaters 2021). In addition, even after the use of DNA characters, molecular phylogenies are often inconsistent and unresolved. The first molecular phylogenies of helotialean taxa were based on SSU and LSU (Platt and Spatafora 2000; Gernandt et al. 2001). Note that for some of the currently recognized orders, sequence data does not currently exist (Lahmiales fide Quandt and Haelewaters 2021) or has only been generated for ribosomal loci (Medeolariales fide LoBuglio and Pfister 2010). In general, limited DNA data are available for most members of the class, notably regarding type specimens.   

Based on the most recent studies, current classifications recognize the following classifications and associations. The first diverging order of the class is Lauriomycetales, followed by Umbellidiales (Barreto et al. 2023). Phylogenies disagree on the relationships of other early diverging orders in the class: Chaetomalleles, Leotiales, Marthamycetales, Micraspidales, Phacidiales, Rhytismatales, and Thelebolales, and their respective relationships to Helotiales (Ekanayaka et al. 2019; Johnston et al. 2019; Haelewaters et al. 2021d; Quijada et al. 2022; Barreto et al. 2023). Historically there has been confusion about how these non-helotialean Leotiomycetes taxa are related to one another (Gernandt et al. 2001; Lantz et al. 2011; Quijada et al. 2018; Karakehian et al. 2019). Within Helotiales, 53 families were recognized by Quandt and Haelewaters (2021), and Johnston et al. (2019) recognized the discinelloid, erysiphoid, helotioid, hyaloscyphoid, mollisioid, pezizelloid, and sclerotinioid clades. 

The total number of species in the class differs depending on the classification system. According to Wijayawardene et al. (2020a), Leotiomycetes comprises 13 orders and 52 families, for a total of 626 accepted genera and 6,453 species, with a major part of incertae sedis genera and species distributed in Helotiales. Quandt and Haelewaters (2021) synthesized the numbers of genera and species per family in the then-current classification of Leotiomycetes and presented 13 orders, with 43 families, 630 genera, and a total of 6,440 species. The most recent compilation of known species and genera of Leotiomycetes was presented by Wijayawardene et al. (2022a) and resulted in eleven orders, 55 families, 633 genera, and 6,451 species.

Type order: Leotiales Korf & Lizoň, Czech Mycol. 52(4): 256 (2001).

Type family: Leotiaceae Corda, Icon. fung. (Prague) 5: 37 (1842).

Type genus: Leotia Pers., Neues Mag. Bot.: 31 (1794).

Type species: Leotia lubrica (Scop.) Pers., Neues Mag. Bot.: 31 (1794).

Other accepted species: Species Fungorum – search Leotiomycetes.

 

Figure 1 – Leotiomycetes fungi. a. Lachnella sp., apothecial margins with conspicuous hairs, Vestmannaeyjabær, Iceland (Lachnaceae, Helotiales). b. Phialocephala sp., Calf Island, Boston Harbor Islands, Massachusetts, USA (Mollisiaceae, Helotiales). c. Chlorosplenium cusucoense nom. prov. (as Chlorosplenium sp. 1 in Haelewaters et al. 2021e), Boquete, Panama (Chlorospleniaceae, Helotiales). d. Erioscyphella sp. nov., ascomata on rotting wood, Boquete, Panama (Lachnaceae, Helotiales). e. Propolis farinosa, erumpent apothecia on branch of Populus sp, Peddocks Island, Boston Harbor Islands, Massachusetts, USA (Marthamycetaceae, Rhytismatales). f. Leotia sp. nov., Koussoucoingou, Benin (Leotiaceae, Leotiales). g. Pezoloma sp., apothecia on dead leaf of Acer saccharinum, New Durham, New Hampshire, USA (Discinellaceae, Helotiales). h. Chlorosplenium chlora, Aia, Basque Province of Gipuzkoa, Spain (Chlorospleniaceae, Helotiales). i. Pezoloma sp., transverse section of 2–4-mm wide apothecium (Discinellaceae, Helotiales). j. Hymenoscyphus sp. nov., ascus tip in Melzer’s reagent, Caribou, Colorado. k. Ascocoryne sp., asci in Melzer’s reagent, World’s End Peninsula, Boston Harbor Islands, Massachusetts, USA (Gelatinodiscaceae, Helotiales). Scale bars: j, k = 10 μm. Photos: a, b, c, k. Danny Haelewaters; e. Alden C. Dirks; d. C. Alisha Quandt; f. Meike Piepenbring; g, i. Jason M. Karakehian; h. Joaquin Martin; j. Candice C. Perrotta.

 

References

Barreto GG, Bezerra JD, Costa-Rezende DH, Gusmão LF et al. 2023 – A multigene phylogeny of Umbellidion revealed a novel lineage in Leotiomycetes. Mycol Prog 22(7):48.

Crous PW, Wingfield MJ, Burgess TI, Carnegie AJ et al. 2017 – Fungal Planet description sheets 625–715. Persoonia 39:270–467.

Ekanayaka AH, Hyde KD, Gentekaki E, McKenzie EHC et al. 2019 – Preliminary classification of Leotiomycetes. Mycosphere 10(1), 310–489.

Eriksson OE, Winka W. 1997 – Supraordinal taxa of Ascomycota. Myconet. 1:1–16.

Eriksson OE. 2005 – Outline of Ascomycota 2005. Myconet 11:1–113

Gernandt DS, Platt JL, Stone JK, Spatafora JW et al. 2001 – Phylogenetics of Helotiales and Rhytismatales based on partial small subunit nuclear ribosomal DNA sequences. Mycologia 93(5):915–933.

Haelewaters D, Park D, Johnston PR. 2021c – Multilocus phylogenetic analysis reveals that Cyttariales is a synonym of Helotiales. Mycol Prog 20(10):1323–1330.

Haelewaters D, Peterson RA, Nevalainen H, Aime MC. 2021d – Inopinatum lactosum gen. & comb. nov., the first yeast-like fungus in Leotiomycetes. Int J Syst Evol Microbiol 71(7):4862.

Johnston PR, Quijada L, Smith CA, Baral HO et al. 2019 – A multigene phylogeny toward a new phylogenetic classification of Leotiomycetes. IMA fungus 10:1–22.

Karakehian JM, Quijada L, Friebes G, Tanney JB et al. 2019 – Placement of Triblidiaceae in Rhytismatales and comments on unique ascospore morphologies in Leotiomycetes (Fungi, Ascomycota). MycoKeys 54:99–133.

Lantz H, Johnston PR, Park D, Minter DW et al. 2011 – Molecular phylogeny reveals a core clade of Rhytismatales. Mycologia 103(1):57–74.

LoBuglio KF, Pfister DH. 2010 – Placement of Medeolaria farlowii in the Leotiomycetes, and comments on sampling within the class. Mycol Prog 9:361–368.

Otani Y. 1982 – Cup fungi in Nepal 1. pp. 75–91. In: Otany Y. (ed.) Reports on the Cryptogamic study in Nepal. National Science Museum Tokyo.

Prieto M, Schultz M, Olariaga I, Wedin M et al. 2019 – Lichinodium is a new lichenized lineage in the Leotiomycetes. Fungal Divers 94(1):23–39.

Quandt CA, Haelewaters D. 2021 – Phylogenetic Advances in Leotiomycetes, an understudied clade of taxonomically and ecologically diverse fungi. 284–294. In: Zaragoza Ó, Casadevall A (eds.) Encyclopedia of Mycology.1. Elsevier, Oxford.

Quijada L, Johnston PR, Cooper JA, Pfister DH et al. 2018 – Overview of Phacidiales, including Aotearoamyces gen. nov. on Nothofagus. IMA fungus 9:371–382.

Quijada L, Tanney JB, Popov E, Johnston PR et al. 2020 – Cones, needles and wood: Micraspis (Micraspidaceae, Micraspidales fam. et ord. nov.) speciation segregates by host plant tissues. Fungal Syst Evol 5(1):99–112

Rossman AY, Aime MC, Farr DF, Castlebury LA et al. 2004 – The coelomycetous genera Chaetomella and Pilidium represent a newly discovered lineage of inoperculate discomycetes. Mycol Prog 3:275–290.

Wang Z, Johnston PR, Takamatsu S, Spatafora JW et al. 2006 – Toward a phylogenetic classification of the Leotiomycetes based on rDNA data. Mycologia 98(6):1065–1075.

Wijayawardene NN, Hyde KD, Al-Ani LKT, Tedersoo L et al. 2020a – Outline of Fungi and fungus-like taxa. Mycosphere 11:1060–1456.

Wijayawardene NN, Hyde KD, Dai DQ, Sánchez-García M et al. 2022a – Outline of Fungi and fungus-like taxa – 2021. Mycosphere 13:53–453.

Baral HO, Haelewaters D, Pärtel K. 2015 – A new attempt to classify the families of the Helotiales. In: The second international workshop on ascomycete systematics. CBS symposium 22–24.

 

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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