Polyphyly of the genus Canoparmelia—uncovering incongruences between phenotype-based classification and molecular phylogeny within lichenized Ascomycota (Parmeliaceae)

Abstract

Many phenotypical features traditionally used to classify genera in Parmeliaceae and in lichens in general have evolved several times independently, potentially limiting their taxonomic utility. Here, we aim to elucidate evolutionary relationships of Canoparmelia s. lat. among other parmotremoid taxa. A multilocus dataset (ITS, nuLSU and mtSSU rDNA sequences) was gathered and analyzed within a phylogenetic framework. Canoparmelia s. lat. was recovered as highly polyphyletic within the parmelioid clade, and three divergent lineages representing Canoparmelia s. lat. were identified in addition to the previously segregated Crespoa group. Of these, two formed a sister relationship with Parmotrema. However, no apparent diagnostic morphological features were found distinguishing the distinct Canoparmelia s. lat. clades reconstructed in the phylogenetic analyses. As a consequence, we propose to restrict the circumscription of Canoparmelia to clade 1 (i.e. the C. texana group) and to include clades 2 and 3 in Parmotrema. We propose to recognize these well-supported monophyletic clades at subgeneric level. Consequently, the new subgeneric name Parmotrema subgen. Africanae is proposed for clade 3 recovered in this study. Since clade 4, which clusters with the genera Nesolechia and Punctelia, is only represented by a single sequenced specimen, we refrain from proposing any taxonomic changes. The new combinations Parmotrema epileucum, and P. zimbabwense are proposed.

Phylogenetic analyses support the recent placement of Canoparmelia scrobicularis into Crespoa (Parmeliaceae, lichenized Ascomycota)

“…The monophyly of Austroparmelina, Canoparmelia s. str., and Parmotrema in the ITS topology is consistent with previous studies (Blanco et al 2005, 2006, Crespo et al 2010a-b, Divakar et al 2013, Kirika et al 2016.…”

“…Apart from molecular data, there are few characters in parmelioid lichens that could be consider truly synapomorphic (Crespo et al 2011). Although more recently Kirika et al (2016) and Divakar et al (2017) subsumed this group as a subgenus within Parmotrema, we agree with Lendemer & Hodkinson (2012) and consider this as a separate genus from Parmotrema.…”

“…All Crespoa species have a rather distinctive thallus structure, with a strongly reticulately ridged and wrinkled upper surface, and medullary stictic and constictic acids, with the exception of C. schelpei, which has medullary protocetraric acid (Hawksworth 2011). More recently, Kirika et al (2016) subsumed Crespoa at subgeneric level within Parmotrema, as initially proposed by Hawksworth (2011).…”

“…Canoparmelia Elix & Hale, as traditionally circumscribed, includes species with relatively narrow, eciliate lobes, a pored epicortex, cell walls with isolichenan, and simple rhizines (Elix et al 1986, Elix 1993. Phylogenetic studies based on molecular data have shown this parmelioid genus was actually highly polyphyletic, as it splits into four separate groups within the Parmotrema clade (Crespo et al 2010a, Kirika et al 2016. One of them, including four species of the Canoparmelia crozalsiana group, was later segregated in the genus Crespoa (D.Hawksw.)…”

Molecular systematics and character evolution in the lichen family Ramalinaceae (Ascomycota: Lecanorales)

“…Molecular phylogenetic studies -such as the present one -are therefore essential for revealing occurrences of convergent evolution or parallelism within these traditionally morphology-based classifications, and to guide taxonomic genus delimitation. Similar instances of polyphyly can be found throughout several other lichen families and genera (e.g., Divakar & al., 2006;Bendiksby & Timdal, 2013;Kirika & al., 2016;Zhao & al., 2016). In our study, we show that phenotypic features, such as the growth form or the presence of a prothallus, are often a result of adaptation to a Table 2.…”