Ericoid mycorrhiza is arguably the least investigated mycorrhizal type, particularly when related to the number of potential hosts and the ecosystems they inhabit. Little is known about the global distribution of ericoid mycorrhizal (ErM) fungi, and this holds true even for the prominent ErM mycobiont Rhizoscyphus ericae. Earlier studies suggested R. ericae might be low in abundance or absent in the roots of Southern Hemisphere's Ericaceae, and our previous investigations in two Argentine Patagonian forests supported this view. Here, we revisited the formerly investigated area, albeit at a higher altitude, and screened fungi inhabiting hair roots of Gaultheria caespitosa and Gaultheria pumila at a treeless alpine site using the same methods as previously. We obtained 234 isolates, most of them belonging to Ascomycota. In contrast to previous findings, however, among 37 detected operational taxonomic units (OTUs), OTU 1 (=R. ericae s. str.) comprised the highest number of isolates (87, ∼37 %). Most of the OTUs and isolates belonged to the Helotiales, and 82.5 % of isolates belonged to OTUs shared between both Gaultheria species. At the alpine site, ericoid mycorrhizal fungi dominated, followed by dark septate endophytes and aquatic hyphomycetes probably acting as root endophytes. Our results suggest that the distribution of R. ericae is influenced, among others, by factors related to altitude such as soil type and presence/absence and type of the neighboring vegetation. Our study is the first report on R. ericae colonizing Ericaceae roots in the Southern Hemisphere and extends the known range of this prominent ErM species to NW Patagonia.

Department of Mycorrhizal Symbioses Institute of Botany CAS Průhonice CZ 252 43 Czech Republic Department of Plant Experimental Biology Faculty of Science Charles University Prague Prague CZ 128 44 Czech Republic

DNA Laboratory Institute of Botany Czech Academy of Sciences Průhonice CZ 252 43 Czech Republic

Laboratorio de Microbiología Aplicada y Biotecnología Centro Regional Universitario Bariloche INIBIOMA Bariloche Río Negro Argentina

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