Fungi Inhabiting Attine Ant Colonies: Reassessment of the Genus Escovopsis and Description of Luteomyces and Sympodiorosea Gens
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Montoya et al. IMA Fungus (2021) 12:23 https://doi.org/10.1186/s43008-021-00078-8 IMA Fungus RESEARCH Open Access Fungi inhabiting attine ant colonies: reassessment of the genus Escovopsis and description of Luteomyces and Sympodiorosea gens. nov. Quimi Vidaurre Montoya1,2* , Maria Jesus Sutta Martiarena1,2 , Rodolfo Bizarria Jr.1,2 , Nicole Marie Gerardo3 and Andre Rodrigues1,2* Abstract Escovopsis is a diverse group of fungi, which are considered specialized parasites of the fungal cultivars of fungus- growing ants. The lack of a suitable taxonomic framework and phylogenetic inconsistencies have long hampered Escovopsis research. The aim of this study is to reassess the genus Escovopsis using a taxonomic approach and a com- prehensive multilocus phylogenetic analysis, in order to set the basis of the genus systematics and the stage for future Escovopsis research. Our results support the separation of Escovopsis into three distinct genera. In light of this, we redefne Escovopsis as a monophyletic clade whose main feature is to form terminal vesicles on conidiophores. Conse- quently, E. kreiselii and E. trichodermoides were recombined into two new genera, Sympodiorosea and Luteomyces, as S. kreiselii and L. trichodermoides, respectively. This study expands our understanding of the systematics of Escovopsis and related genera, thereby facilitating future research on the evolutionary history, taxonomic diversity, and ecological roles of these inhabitants of the attine ant colonies. Keywords: Attina, Evolution, Fungus-growing ants, Hypocreaceae, Symbiosis, Systematics, Four new taxa Introduction Escovopsis is a diverse group of fungi, members of which Te kingdom Fungi comprises organisms with wide mor- are presumed to have evolved parasitizing the mutual- phological and genetic diversity (Mueller and Schmit istic fungus of fungus-growing ants (Formicidae: Myr- 2007; Hawksworth and Lücking 2017). Trough system- micinae: Attini: Attina, the “attines”) (Yek et al. 2012). atic approaches, taxonomists have developed mecha- Besides, Escovopsis has only been found associated with nisms to categorize organisms based on their phenotypic fungus-growing ant colonies, suggesting that the genus and genetic characters (Komarek and Beutel 2006; Pav- has evolved in relation to these ants’ system, potentially linov 2018). Notwithstanding, taxonomic and phyloge- for millions of years. Despite its biological importance in netic incongruities like non-monophyly preclude the relation to a canonical system for the study of coevolu- study of many fungal groups, as is the case for the genus tion and symbiosis, the paucity of taxonomic studies and Escovopsis (Ascomycota: Hypocreales, Hypocreaceae). unresolved phylogenetic inconsistencies have prevented a comprehensive understanding of the systematics, ecol- ogy, and evolution of these hypocrealean fungi. *Correspondence: [email protected]; [email protected] More than a century has passed since Möller (1893) 1 Department of General and Applied Biology, São Paulo State University (UNESP), Avenida 24-A, n. 1515, Bela Vista, Rio Claro, SP 13.506-900, Brazil observed a group of “fungi with strong conidial shapes” Full list of author information is available at the end of the article (i.e. more prevalent fungi) in attine gardens, which © The Author(s) 2021. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http:// creat iveco mmons. org/ licen ses/ by/4. 0/. Montoya et al. IMA Fungus (2021) 12:23 Page 2 of 18 80 years later would be named Phialocladus (Krei- for the ex-type culture of E. weberi) suggested that the sel 1972). Almost two decades later, Phialocladus was genus may not be monophyletic. considered an invalid name because of the lack of the For almost 30 years, the genus Escovopsis was mor- type specimen for its type species, P. zsoltii, and con- phologically defned by the presence of conidiophores sequently, it was renamed as Escovopsis with E. weberi with vesicles that support the phialides (i.e., enteroblastic designated as the type species of the latter genus conidiogenous cells), from which conidia are produced. (Muchovej and Della Lucia 1990). Although the macro- However, that changed with the introduction of Escov- scopic characters of E. weberi were not fully described opsis trichodermoides (Masiulionis et al. 2015) and E. by the authors, the description of this species estab- kreiselii (Meirelles et al. 2015a). Tese species have con- lished the foundation for Escovopsis taxonomy. In 1995, idiophores without vesicles and with poorly diferenti- Seifert et al. (1995) described Escovopsis aspergilloides ated conidiogenous cells (i.e., holoblastic determinate in a detailed taxonomic study. However, after this study, conidiogenous cells with synchronous arrangement; E. the taxonomy of Escovopsis was set aside for 18 years. trichodermoides) and sympodial conidiogenous cells (i.e., Unlike systematics studies, the relationship between holoblastic proliferous conidiogenous cells; E. kreiselii) Escovopsis and the attine ants’ mutualistic fungi has instead of phialides. Terefore, Meirelles et al. (2015a) been the topic of numerous studies (Currie et al. 2003; amended the morphological description of Escovopsis Gerardo et al. 2006a, b; Taerum et al. 2007; Folgar- to insert the morphological features of E. kreiselii. How- ait et al. 2011; Elizondo Wallace et al. 2014; Marfetán ever, because Masiulionis et al. (2015) and Meirelles et al. et al. 2015; Birnbaum and Gerardo 2016; de Man et al. (2015a) were published at nearly the same time, the new 2016; Heine et al. 2018). A great diversity was attrib- defnition did not include E. trichodermoides. uted to the genus Escovopsis through these studies, yet Te insertion of E. trichodermoides and E. kreiselii the morphology and phylogenetic placement of most within Escovopsis not only meant changes to the mor- of the strains named as Escovopsis were not properly phological circumscription of the genus but also intensi- assessed. Te frst ideas about the phylogenetic position fed the phylogenetic uncertainties showed by Augustin of Escovopsis were gradually emerging (Currie et al. et al. (2013). In the phylogenies produced by Masiulionis 2003; Gerardo et al. 2006b; Augustin et al. 2013; Masi- et al. (2015) and Meirelles et al. (2015a, b), it was clear ulionis et al. 2015; Meirelles et al. 2015a, b). Initially, that vesiculate Escovopsis were more closely related to some authors suggested that Escovopsis belonged to the Escovopsioides (Augustin et al. 2013) than to E. tricho- Hypocreales, although, no phylogenetic evidence was dermoides and E. kreiselii. Nonetheless, both Masiulionis provided to support that hypothesis at the time (Currie et al. (2015) and Meirelles et al. (2015a, b) preferred to et al. 1999a, b). Te frst phylogenetic analysis of Escov- maintain E. trichodermoides, E. kreiselii and the vesicu- opsis confrmed the genus to be placed in the Hypocre- late Escovopsis as placing in the same genus. ales, as a sister clade of the Hypocreaceae (Currie et al. Recently, Montoya et al. (2019) used the ITS, LSU, 2003). However, a more extensive phylogenetic analysis and tef1 markers in a multilocus phylogenetic approach of Escovopsis strains associated with fungus gardens of to describe Escovopsis clavata and E. multiformis. Te Apterostigma ants indicated that the genus belonged to authors noticed that disagreements in the Escovopsis tax- the Hypocreaceae (Gerardo et al. 2006b). onomy occurred among vesiculate Escovopsis, E. tricho- Augustin et al. (2013) were the frst authors to com- dermoides and E. kreiselii. Terefore, they highlighted the bine morphological and phylogenetic approaches need to utilize new molecular markers to resolve the phy- to study Escovopsis. Based on internal transcribed logeny of the genus. However, subsequent description of spacer (ITS) and large subunit ribosomal RNA (LSU) fve new Escovopsis species (Marfetán et al. 2018) further sequences, the authors described Escovopsis lentecre- complicated Escovopsis taxonomy because interpreta- scens, E. microspora, and E. moelleri, which formed tion of the phylogenetic analyses made by Marfetán et al. a monophyletic clade with E. weberi and E. aspergil- (2018) had some limitations: (1) it was based on the LSU loides. Te most remarkable character of these newly and tef1 genes separately; (2) the tef1 sequences obtained named species was the presence of conidiophores with in the study do not align with those sequences in previ- vesicles, as previously described by Muchovej and Della ously published studies; (3) some LSU sequences do not Lucia (1990) and Seifert et al. (1995). Nonetheless, have similarity with Escovopsis; and (4) some of the new while phylogenetic analyses of Augustin et al. (2013) species (Escovopsis atlas, E. catenulata,