sp. URa15—Hochtor; Trebouxia sp. URa8—abernas;

T. sp. URa12—Gynge Alvar; T. sp. URa13—Hochtor). Table 4 Overview of chlorobiont occurrence in the four SCIN habitats   Genus Tabernas/Spain Hochtor/Austria Ruine Homburg/ Germany Gynge/Sweden Clades/ species Asterochloris sp. – 2 3 2 Chloroidium saccharophilum – 1 – – Trebouxia sp. 4 5 5 5 Other EGMA – 4 7 2 Other EGMA other eukaryotic green micro algae The key lichen P. decipiens occurred not only at all SCIN habitats but also in all additional soil crust specimens from other high Alpine areas. In most cases each individual lichen specimen contained one or more photobionts from every clade together with other eukaryotic green micro algae (EGMA; see Online Resource 1). The species specificity of the mycobiont towards its PD0332991 clinical trial photobiont was quite low for P. decipiens. In contrast, Fulgensia bracteata ssp. deformis (which has so far only been found in samples from Hochtor) only occurred BAY 57-1293 cell line with T. sp. URa4 and A. sp. URa15 (the latter until now only known from this area, Figs. 2, 3). Peltigera rufescens, known to have a cyanobacterium as its primary photobiont (O’Brien et al. 2005), was also found to be associated with chlorobionts (Henskens et al. 2012). Specimens of P. rufescens from Ruine Homburg were associated with T. sp. URa6 and A. sp. URa16, although other

chlorobionts were available at the site; at Hochtor P. rufescens was found with T. impressa (see Online Resource 1, Figs. 2, 3). Discussion This evaluation of European lichen-dominated soil crusts from four geographically and climatically diverse sites revealed an unexpectedly high diversity of photobionts click here in association with the dominant lichen P. decipiens. Until now, only the genus Asterochloris has been described as the photobiont of P. decipiens (Schaper and Ott 2003), but we detected 12 different groups of the genus Trebouxia unless as well as other eukaryotic green micro algae like C. saccharophilum. Several of these micro algae are already known to exist as lichen photobionts, such as T. impressa, T. asymmetrica or the, as yet undescribed, Trebouxia sp. URa2, URa4, URa6.

The latter three species have also been identified as photobionts from crustose lichens (Ruprecht et al. 2012). Other Trebouxia species that are known as free-living algae (e.g. T. arboricola; Ettl and Gärtner 1995) were included in the analysis but not found in the soil-crust samples. P. decipiens at Hochtor showed a shared use of the available photobionts with other lichen species that were present (see Online Resource 1) with each species having a different level of specificity towards to its photobiont. We can conclude for P. decipiens that this lichen is not limited to a single species or even genus of photobiont but instead associates with a broad range of apparently locally available algae. The low specificity of P.