Specialist taxa restricted to threatened habitats contribute significantly to the regional diversity of Peltigera (Lecanoromycetes, Ascomycota) in Estonia

Abstract

The widespread cyanolichen genus Peltigera comprises many insufficiently known poorly delimited and/or undescribed species. Phylogenetic analysis of 252 Peltigera specimens from a wide range of habitat types in Estonia revealed 31 putative taxa (OTUs). Multivariate analysis revealed habitat-specific segregation between the Peltigera species along a gradient from humid eutrophic forests to dry oligotrophic forests and grasslands and along a soil pH gradient from alkaline soils of alvar grasslands to acidic soils of conifer forests. The diversity of Peltigera was the highest on roadsides and dunes and the lowest in alvar habitats which, however, supported the unique assemblage of undescribed Peltigera taxa. Deciduous broad-leaved forests, too, included several undescribed or rare and red-listed species. The results demonstrate that in Estonia many Peltigera species have narrow habitat requirements and are at present threatened by habitat loss and degradation.

Species delimitation at a global scale reveals high species richness with complex biogeography and patterns of symbiont association in Peltigera section Peltigera (lichenized Ascomycota: Lecanoromycetes)

“…Whether Peltigera singletons represent distinct species or artifacts of the implemented methods awaits further testing based on additional samples bridging the current localities (often distant) and using complementary methods that rely on other models with different assumptions. Our analyses confirmed that some taxa introduced informally in previous studies (Miadlikowska & Lutzoni, 2000;Jüriado & al., 2017) represent undescribed species, or assemblages of undescribed species, delimited consistently by multiple methods (e.g., Peltigera "fuscopraetextata", P. "neocanina" and P. "neorufescens"). Other provisionally named taxa should be merged (as indicated by , such as P. "pallidorufescens", which is synonymous with P. "fuscopraetextata", and P. "fuscoponojensis" which is nested within the P. "neorufescens" clade.…”

“…neocanina corresponds to our P. "neocanina" 4, collected in Norway and Iceland. Apart from the hyperdiverse P. "neorufescens" complex, all lineages detected in section Peltigera by Jüriado & al. (2017) were also sampled in our study.…”

“…A recent study (Jüriado & al., 2017) reported a high level of undescribed species in section Peltigera collected in Estonia. Several lineages recognized by the authors based on ITS sequences correspond to species delimited in this study using multiple loci and methods.…”

“…3 in Goffinet & al., 2003), respectively. Peltigera lepidophora from Jüriado & al. (2017) corresponds to our P. lepidophora 1, a species already known from Europe and North America and their P. aff.…”

“…(2018) reported that Peltigera species had narrower ranges and showed a high degree of specialization towards more widespread generalist Nostoc phylogroups, and that bioclimatic factors were more limiting in the mycobiont distributions than the availability of cyanobionts. A recent study in Estonia (Jüriado & al., 2017) found most species of section Peltigera, many of which were undescribed, to have narrow habitat requirements. Pardo-De la Hoz & al.…”