The Lichenologist (2020), 52, 287–303 doi:10.1017/S0024282920000225 Standard Paper High levels of endemism and local differentiation in the fungal and algal symbionts of saxicolous lecideoid lichens along a latitudinal gradient in southern South America Ulrike Ruprecht1 , Fernando Fernández-Mendoza2, Roman Türk1 and Alan M. Fryday3 1Universität Salzburg, FB Biowissenschaften, Hellbrunnerstrasse 34, 5020 Salzburg, Austria; 2Karl-Franzens-Universität Graz, Institut für Biologie, Holteigasse 6, 8010 Graz, Austria and 3Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA Abstract Saxicolous, lecideoid lichenized fungi have a cosmopolitan distribution but, being mostly cold adapted, are especially abundant in polar and high-mountain regions. To date, little is known of their origin or the extent of their trans-equatorial dispersal. Several mycobiont genera and species are thought to be restricted to either the Northern or the Southern Hemisphere, whereas others are thought to be widely distributed and occur in both hemispheres. However, these assumptions often rely on morphological analyses and lack supporting molecular genetic data. Also unknown is the extent of regional differentiation in the southern polar regions. An extensive set of lecideoid lichens (185 samples) was collected along a latitudinal gradient at the southern end of South America. Subantarctic climate conditions were maintained by increasing the elevation of the collecting sites with decreasing latitude. The investigated specimens were placed in a global context by includ- ing Antarctic and cosmopolitan sequences from other studies. For each symbiont three markers were used to identify intraspecific variation (mycobiont: ITS, mtSSU, RPB1; photobiont: ITS, psbJ-L, COX2). For the mycobiont, the saxicolous genera Lecidea, Porpidia, Poeltidea and Lecidella were phylogenetically re-evaluated, along with their photobionts Asterochloris and Trebouxia. For several globally distributed spe- cies groups, the results show geographically highly differentiated subclades, classified as operational taxonomical units (OTUs), which were assigned to the different regions of southern South America (sSA). Furthermore, several small endemic and well-supported clades appar- ently restricted to sSA were detected at the species level for both symbionts. Key words: glacial refugia, global distribution, pioneer vegetation on rock, subantarctic subregion (Accepted 20 December 2019) Introduction Schmull et al. 2011;Ruprechtet al. 2012a, 2016; Fryday & Hertel 2014;Zhaoet al. 2015). Saxicolous ‘lecideoid’ lichens (Hertel 1984)aregeneraandspecies The family Porpidiaceae was erected by Hertel & Hafellner usually described originally under the generic name Lecidea sensu (Hafellner 1984) to accommodate the genus Porpidia along with Zahlbruckner (1925) and comprise crustose species with apothecia other genera formerly included in the Lecideaceae that had a lacking a thalline margin and with non-sepate ascospores. As such Porpidia-type ascus structure. However, Buschbom & Mueller they are a heterogenous, non-monophyletic group and, although (2004) showed that Lecidea was phylogenetically nested within some do belong to the genus Lecidea s. str. (Lecideaceae Chevall.), the Porpidiaceae and so the latter family was included in the syn- most belong to other genera and/or families, such as Porpidia onymy of the Lecideaceae (Lecideales) by Lumbsch & Huhndorf Körb, Poeltidea Hertel & Hafellner and Cyclohymenia McCune & (2010), and this is still the case in the current issue of Outline M. J. Curtis (Lecideaceae), Carbonea (Hertel) Hertel and Lecidella of Ascomycota: 2017 (Wijayawardene et al. 2018). The genera Körb. (Lecanoraceae Körb.). In addition to their morphological Lecidea s. str. (Hertel 1984), Porpidia and Poeltidea as well as similarities, lecideoid lichenized fungi are strongly associated Cyclohymenia and Farnoldia Hertel are all assigned to this family, with green microalgal photobionts of the cosmopolitan class although Farnoldia appears to occupy a peripheral position. The Trebouxiophyceae (Hertel 1984, 2007; Buschbom & Mueller 2004; other genus investigated here, Lecidella was also originally included in the Lecideaceae but the species of this genus have an ascus structure very similar to the Lecanora-type and so the Dedicated to Hannes Hertel on his 80th birthday in appreciation of his life-long inves- genus was included in the Lecanoraceae by Hafellner (1984), tigation of lecideoid lichens. which is still its current position (Wijayawardene et al. 2018). The inconspicuous morphology of ‘lecideoid’ lichens compli- Author for correspondence: Ulrike Ruprecht. E-mail: [email protected] cates their systematic treatment. Large taxonomic groups are Cite this article: Ruprecht U, Fernández-Mendoza F, Türk R and Fryday AM (2020) High levels of endemism and local differentiation in the fungal and algal symbionts of often distinguishable by just a small number of microscopic traits, saxicolous lecideoid lichens along a latitudinal gradient in southern South America. such as spore size and septation or ascus-type, but species-level Lichenologist 52, 287–303. https://doi.org/10.1017/S0024282920000225 identification can be difficult, often relying on subtle characters © British Lichen Society 2020. This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution, and reproduction in any medium, provided the original work is properly cited. Downloaded from https://www.cambridge.org/core. IP address: 170.106.33.19, on 26 Sep 2021 at 00:24:21, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0024282920000225 288 Ulrike Ruprecht et al. such as excipulum pigmentation and structure or the secondary vicinity and interconnection of continental shelves, or 2) by tran- metabolites produced. The fundamental taxonomic work on leci- sition from the Arctic to Patagonia in the Pleistocene, resulting in deoid lichens (Hafellner 1984; Hertel 1984;Gowan1989; Knoph cryptic specialization, as shown in the bipolar lichen Cetraria & Leuckert 1994; Inoue 1995; Castello 2003; Knoph et al. 2004; aculeata (Fernández-Mendoza & Printzen 2013), or 3) by glacial Fryday 2005; Fryday & Hertel 2014) has mostly used morpho- refugia during the last ice ages at the southern end of South logical and chemical characters, but lacks molecular genetic America (Paula & Leonardo 2006). A good example of this last data. Extensive collections, especially from the Southern scenario is the highly differentiated and endemic lichen species Hemisphere, are very often older than 50 years which precludes Porpidia navarina U. Rupr. & Türk, which is known only from the use of molecular methods because of the common problem one of the southernmost islands (Isla Navarino) that was ice of DNA degradation in mycobiont specimens older than 20 free during the Last Glacial Maximum (Douglass et al. 2005; years. During the last decade, molecular re-evaluations have Ruprecht et al. 2016). Additionally, evolutionary processes such helped to redefine the species concepts behind these diverse as adaptation and subsequent specialization to the harsh climate groups but were mostly focused on the Northern Hemisphere conditions in Antarctic cold deserts (Ruprecht et al. 2010, (Buschbom & Mueller 2004; Schmull et al. 2011; Orange 2014; 2012b; Schroeter et al. 2011) can also lead to high local differen- Zhao et al. 2015, 2016; McCune et al. 2017) and Antarctica tiation in global species and endemism in the southern polar (Ruprecht et al. 2010, 2012b). However, Hale et al. (2019) recently regions. demonstrated a biogeographical connection between the Lecidea Lichens are ideal model-systems to test these hypotheses species of western North America and the southern polar regions, because several genera and species are globally distributed and helping to provide a better understanding of distribution and spe- form locally differentiated subgroups (Fernández-Mendoza et al. ciation patterns in this group. Nevertheless, intermediate latitudes 2011). Additionally, at least double the information is available in the Southern Hemisphere remain understudied and recently compared to other organisms because lichens consist of a symbi- published results (Ruprecht et al. 2016) have emphasized the otic relationship between two or more independently distributed extent of the knowledge gap in southern South American leci- partners. This main symbiotic relationship is formed by a fungus deoid lichens, not only from the mycobiont perspective but also (mycobiont) and green algae and/or cyanobacteria (photobiont). from that of the associated green microalgae. Furthermore, a diverse community of associated bacteria (Grube The use of DNA sequence data and phylogenetic methods has et al. 2015; Aschenbrenner et al. 2016), algae (Peksa & Škaloud revealed that cosmopolitan genera often show locally differentiated 2011; Ruprecht et al. 2014; Moya et al. 2017), endolichenic or subgroups or cryptic species, which can be influenced by ecological lichenicolous fungi and basidiomycete yeasts (Lawrey & factors and may be restricted to isolated areas (Walser et al. 2005; Diederich 2003; Arnold et al. 2009; Spribille et al. 2016)are Leavitt et al. 2011; Lumbsch & Leavitt 2011;Brancoet al. 2015; part of the lichen thallus. Kraichak et al. 2015). Lichens, as well