Phylogenetic revision of the genus Peltigera (lichen-forming Ascomycota) based on morphological, chemical, and large subunit nuclear ribosomal DNA data

Peltigera (Peltigerineae, lichenized Ascomycota) is one of the most widespr ead lichen genera incorporating bi- and trimembered associations involving fungi, green algae (cf. Coccomyxa), and cyanobacteria (cf. Nostoc). A wide range of morphological and chemical (secondary compounds), variation at bot h the intra- and interspecific levels is present in this genus. Compared to many other genera of macrolichens, its taxonomy, including chemotaxonomy, still remains poorly understood. Existing infrageneric classifications of P eltigera are almost exclusively based on photobiont composition of the thal lus. These classifications assumed that bi- and trimembered taxa were disti nct monophyletic entities. The genus Peltigera has never been the focus of a comprehensive phylogenetic study. The most recent and widely accepted sub division of the genus into seven groups is based mainly on morphological an d chemical characters. Relationships among species of Peltigera are investi gated here using chemical, morphological, and large subunit nuclear ribosom al DNA (LSU nrDNA) data. We test the monophyly of these seven morpho-chemic al Peltigera groups and propose a classification based on a phylogenetic ap proach. Data sets of 42 chemical characters (terpenoids), 31 morphological characters, and 1135 LSU nrDNA characters for 96 samples representing 38 Pe ltigera species, eight undescribed putative Peltigera species, and nine spe cies from seven potentially closely related genera from Peltigerineae were subjected to maximum parsimony analyses. Morphological, chemical, and molec ular analyses were carried out independently and on a combined data set. Mo nophyly of Peltigera, including Hydrothyria, was confirmed. The genus Hydro thyria is transferred to Peltigera and a new combination Peltigera hydrothy ria Miadlikowska & Lutzoni is proposed. Eight monophyletic sections within the genus Peltigera, with high bootstrap support, are circumscribed: sectio ns Peltigera, Polydactylon Miadlikowska & Lutzoni, Chloropeltigera Gyeln., Peltidea (Ach.) Vain., Horizontales Miadlikowska & Lutzoni, Retifoveatae Mi adlikowska & Lutzoni, Phlebia Wallr., and Hydrothyriae Miadlikowska & Lutzo ni. Unequivocal morphological and chemical synapomorphies for all sections except section Peltidea are recognized and presented. A key for identificat ion of the sections is provided. In addition, a key based on four main terp enoids for determination of the chemotypes and species within section Polyd actylon is included. Five terpenoids (50-54) identified on thin-layer chrom atography plates for P. elisabethae and P. horizontalis chemotype I are add ed to the list of substances found in Peltigera. Five chemotypes, mainly fr om Poland and Norway, are reported from Peltigera thalli for the first time : P, malacea chemotype V, P. leucophlebia chemotype II, P, hymenina chemoty pes II and III, and P. collina chemotype IV. Three main types of vein struc ture in Peltigera were recognized based on SEM studies.