Peltula pannarioides and P. rosulata (Peltulaceae), new lichen species from Baikal Siberia
The objective of the study was to conduct a thorough anatomical, morphological and taxonomic study of the species of the lichen genus Peltula from Baikal Siberia belonging to the group with peltate-umbilicate sorediate thallus (euploca-bolanderi-type). Until now, among over 40 Peltula species, only four ones belonged to this group (P. africana, P. bolanderi, P. euploca and P. farinosa). In addition to the widespread species P. euploca, two new species have been identified, essentially different from all the four previously known members of the group, primarily by the expressed polyphyllous character of the thallus. Descriptions of the new species, P. pannarioides and P. rosulata, with their macro and micro photos and a map of their distribution, are provided. P. pannarioides is characterized by a thick polyphyllous thallus, upturned undulate sorediate margins of lobes, brown-grey reticulate-grained pruinose upper surface, large granulose soredia, thick cracked epinecral layer, and medulla composed of densely interwoven periclinally oriented hyphae. P. rosulata is characterized by thin polyphyllous thallus, upturned undulate sorediate margins of lobes, dark-brown, smooth, matte upper surface, large granulose soredia, thin continuous brownish epinecral layer, and medulla composed of loosely interwoven periclinally and anticlinally oriented hyphae. The territory of Baikal Siberia and of Southern Siberia as a whole may be regarded as one of the centers of the species diversity of genus Peltula, namely of the group of species with polyphyllous umbilicate sorediate thallus. The entire complex of the species with the euploca-bolanderi-type thallus requires more detailed study.