The field study of the P. aphthosa-leucophlebia complex will be concentrated in North America and eastern Russia. This species complex encompasses tri-partite lichens in the sections Chloropeltigera and Peltidea (Fig. 3A-C; Fig. 3D), i.e., P. aphthosa, P. britannica, P. chionophila, P. latiloba, P. leucophlebia, P. nigripunctata, and two putative new species from British Columbia, Canada. One of these two undescribed species seems to be the most common member of this species complex in certain areas of the Pacific Northwest (O’Brien 2006; O’Brien et al. 2009). Although phylogenetically welldefined with molecular data, with some exceptions, these tri-partite lichens are morphologically very similar and are in need of reliable morphological and chemical diagnostic characters. Despite the circumscription and identification of P. frippii and P. malacea (both are bi-membered lichens) are not problematic, these two additional members of the section Peltidea will be included in this detailed revision of this species complex (Fig. 3D).
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Fig. 3. A. P. aphthosa. B. P. leucophlebia. C. P. britannica. D. Single most parsimonious tree resulting from a combined analysis of chemical, morphological, and LSU nrDNA data for a subsample of 54 OTUs (Miadlikowska and Lutzoni, 2000)