Parmelina quercina (Parmeliaceae, Lecanorales) includes four phylogenetically supported morphospecies

Abstract

Morphological and phylogenetic relationships of the worldwide Mediterranean lichen forming fungus, Parmelina quercina , have been studied. Specimens from western Europe, western North America and southern Australia were analysed using molecular data (nuITS rDNA, nuLSU rDNA and mtSSU rDNA) and selected morphological features (upper cortex maculae, scanning electron microscopy examination of the epicortex, ascospores and conidia shape and size, and amphithecial retrorse rhizines). The results conclusively reveal that: (1) there is not one single species but four separate species in the Mediterranean or sub Mediterranean areas of the world. Parmelina quercina and Parmelina carporrhizans (Euroasiatic species), Parmelina coleae sp. nov. (North America) and Parmelina elixia sp. nov. (Australia);(2) largely debated P. carporrhizans is not a synonym of P. quercina but supported as a valid species circumscribed to Macaronesic relict sites; (3) the geographical isolation of the Australian population is correlated with a large genetic distance; (4) morphological characters (ascospores and conidial variability and thallus epicortex) correlate with the phylogenetic hypothesis; (5) the new or revalidated species within Parmelina quercina are not cryptic species but morphologically recognizable taxa.

Cryptic species and species pairs in lichens: A discussion on the relationship between molecular phylogenies and morphological characters

“…Molecular phylogenetic data have led to the revision of morphological and chemical characters and their taxonomical significance in different groups (e.g. Högnabba & Wedin, 2003;Schmitt & al., 2005;Divakar & al., 2005a;Argüello & al., 2007;Gueidan & al., 2007;Kalb & al., 2008) whilst the search for characters to support the phylogenetic topologies has yielded new and useful morphological features that were previously unnoticed (e.g. del .…”

“…However it must be stressed that, in many cases, independent, clearly monophyletic taxa do not possess apparently morphological characters that allow an unequivocal morphological identification. In such cases, and when different geographical distributions are recognizable, several authors have proceeded to propose new species or genera using biogeography as a supporting character (Argüello & al., 2007;Divakar & al., in press). Similarly, different ecological behaviour has also been used to validate the recognition of cryptic taxa, e.g.…”

“…This is the case for several broadly defined morphospecies within the Parmeliaceae (e.g. Parmelia saxa tilis, P. sulcata and Parmelina quercina) which contain different separate phylogenetic clades with identical morphology, and exist side by side in some areas of their distribution range, such as the British Isles, the Iberian Peninsula or the mountains of northern Morocco (Crespo & al., 2002;Argüello & al., 2007).…”

“…For example, several cases have been detected in the Parmeliaceae, where the presence of cryptic species is not restricted to any particular mode of reproduction. Cryptic lineages have been reported in apotheciate taxa such as Parmelina quercina (Argüello & al., 2007), the isidiate Parmelia saxatilis (Crespo & al., 2002;Molina & al., 2004) and the sorediate Parmotrema reticulatum (Divakar & al., 2005b). It should be noted that, although available studies are unequivocal in revealing cryptic lineages within lichen morphospecies, the lack of molecular markers with greater resolution tends to limit studies in some groups of lichens.…”

“…The species was known as a single taxon, occurring in most regions of the world with humid Mediterranean climate, including North America, Australia and Europe. An analysis of genetic variability of P. quercina with several markers (Argüello & al., 2007) that included samples from all the major regions where the species was reported, found several different independent lineages within the species. Specimens from Europe and North Africa were grouped in two independent monophyletic lineages that overlapped geographically.…”