The main aims of this work were to assess phylogenetic relationships of the trentepohlialean photobionts in tropical, mainly sterile, lichens collected in Bolivia, to examine their genetic diversity, host specificity, and the impact of habitat factors on the occurrence of Trentepohliales. Based on rbcL marker analysis, we constructed a phylogenetic tree with eight major clades of Trentepohliales, of which seven free‐living species are intermingled with lichenized ones. Our analyses show that the studied photobionts are scattered across the phylogenetic tree and algae from temperate and tropical regions do not form monophyletic groups, except within one clade that seems to be restricted to the tropics. There is no significant occurrence pattern of lichenized Trentepohliaceae on a specific substratum, except Cephaleuros spp. and Phycopeltis spp., which are restricted to leaves, while some clades with lichenized algae may be specialized to tree bark and wood. Moreover, we found two patterns of associations: first, closely related algae can associate with distantly related mycobionts; second, some other trentepohlioid algae associate with selected lineages of fungi (e.g., Arthoniaceae or Graphidaceae). We also found that some lineages of photobionts are even more selective and associate exclusively with one species (e.g., Dichosporidium nigrocinctum, Diorygma antillarum) or closely related lichen‐forming fungi (Herpothallon spp.). Concluding, we found that occurrence of some trentepohlialean photobionts may correlate with the particular type of the mycobiont.

We studied the biodiversity of Asterochloris photobionts found in Bolivian lichens to better understand their global spatial distribution and adaptation strategies in the context of a worldwide phylogeny of the genus. Based on nuclear ITS rDNA, the chloroplast rbcL gene and the actin type I gene we reconstructed a phylogenetic tree that recovered nine new Asterochloris lineages, while 32 Bolivian photobiont samples were assigned to 12 previously recognized Asterochloris lineages. We also show that some previously discovered Asterochloris photobiont species and lineages may occur in a broader spectrum of climatic conditions, and mycobiont species and photobionts may show different preferences along an altitude gradient. To reveal general patterns of of mycobiont specificity towards the photobiont in Asterochloris, we tested the influence of climate, altitude, geographical distance and effects of symbiotic partner (mycobiont) at the species level of three genera of lichen forming fungi: Stereocaulon, Cladonia and Lepraria. Further, we compared the specificity of mycobionts towards Asterochloris photobionts in cosmopolitan, Neotropical, and Pantropical lichen forming fungi. Interestingly, cosmopolitan species showed the lowest specificity to their photobionts, but also the lowest haplotype diversity. Neotropical and Paleotropical mycobionts, however, were more specific.

In the past few years, new phylogenetic lineages in Trebouxia were detected as a result of molecular approaches. These studies included symbiont selectivity in lichen communities, transects along altitudinal gradients at local and global scales and the photobiont diversity in local populations of lichen-forming fungal species. In most of these studies, phylogenetic and haplotype analyses based on the internal transcribed spacer (ITS) locus have continuously allowed the recognition of new monophyletic lineages, which suggests that still numerous undiscovered Trebouxia lineages can be hidden in lichens from unexplored areas, especially in the tropics. Here, we estimated the biodiversity of photobionts in Bolivian Andean vegetation and assessed their specificity. About 403 lichen samples representing 42 genera, e.g., Haematomma, Heterodermia, Hypotrachyna, Lecanora, Lepra, Leucodermia, Parmotrema, Pertusaria, Polyblastidium, and Usnea, containing Trebouxia photobionts, were analyzed. ITS ribosomal DNA (rDNA) and rbcL markers were used. We obtained Trebouxia sequences from Bolivian samples belonging to already described clades A, C, I, and S. Thirty-nine Trebouxia lineages were distinguished within these clades, while 16 were new. To reveal the structure of the community of Bolivian photobionts and their relationships with mycobionts, the comparative effects of climate, altitude, geographical distances, substrate, and habitat type, as well as functional traits of lichens such as growth forms, propagation mode and secondary metabolites, were analyzed. Furthermore, new Bolivian records were included in analysis on a global scale. In our study, the mycobiont genus or even species are the most important factors correlated with photobiont identity. Moreover, we revealed that the community of Bolivian photobionts is shaped by altitude.

Fuscidea multispora Flakus, Kukwa & Rodr. Flakus and Malmidea attenboroughii Kukwa, Guzow-Krzemińska, Kosecka, Jabłońska & Flakus are described as new to science based on morphological, chemical and molecular characters. Lepra subventosa var. hypothamnolica is genetically and chemically distinct from L. subventosa var. subventosa and a new name, Lepra pseudosubventosa Kukwa & Guzow-Krzemińska, is proposed due to the existence of Lepra hypothamnolica (Dibben) Lendemer & R.C. Harris. Pertusaria muricata, recently transferred to Lepra, is kept in the genus Pertusaria due to the highest similarity of ITS sequence with members of Pertusaria. The occurrence of Micarea hedlundii in the Southern Hemisphere is confirmed based on molecular evidence from Bolivian population. Lepra pseudosubventosa and Pertusaria muricata are reported as new to South America, and 20 taxa as new to Bolivia. Lepraria stephaniana, previously known only from the type locality, is reported from two more sites. An ascosporic state is reported for the first time for Lepra amaroides, as are new chemotypes. Molecular markers were used to place some sterile, sorediate crustose lichens in the family Graphidaceae. The phylogenetic positions of some sterile Malmidea specimens within Malmidaceae are also discussed.

Leprariacryptovouauxii is described as a new semicryptic species similar to L.vouauxii, from which it differs geographically (South America) and phylogenetically; both species differ in nucleotide position characters in nucITS barcoding marker. Leprariaharrisiana is reported as new to South America and L.nothofagi as new to Antarctica, Bolivia, and Peru. Leprariaincana (South American records are referred to L.aff.hodkinsoniana) and L.vouauxii (most South American records are referred to L.cryptovouauxii) should be excluded at least temporarily from the lichen list of South America. All records previously referred to as L.alpina from Bolivia and Peru belong to L.nothofagi. Most of Bolivian records of L.pallida belong to L.harrisiana. Leprariaborealis and L.caesioalba should be included in L.neglecta. Leprariaachariana, L.impossibilis, and L.sipmaniana are sequenced for the first time.