Morphology and secondary chemistry in species recognition of Parmelia omphalodes group - evidence from molecular data with notes on the ecological niche modelling and genetic variability of photobionts.

Emilia Ossowska,Katarzyna Szczepańska,Marta Kolanowska,Martin Kukwa,Beata Guzow-Krzemińska

doi:10.3897/mycokeys.61.38175

Abstract

To evaluate the importance of morphological and chemical characters used in the recognition of species within the Parmelia omphalodes group, we performed phylogenetic, morphological and chemical analyses of 335 specimens, of which 34 were used for molecular analyses. Phylogenetic analyses, based on ITS rDNA sequences, show that P. pinnatifida is distinct from P. omphalodes and the most important difference between those species is the development of pseudocyphellae. In P. pinnatifida, they are mostly marginal and form white rims along lobes margins, but laminal pseudocyphellae can develop in older parts of thalli and are predominantly connected with marginal pseudocyphellae. In contrast, in P. omphalodes laminal pseudocyphellae are common and are predominantly not connected to marginal pseudocyphellae. Chemical composition of secondary lichen metabolites in both analysed species is identical and therefore this feature is not diagnostic in species recognition. Few samples of P. discordans, species morphologically similar to P. omphalodes and P. pinnatifida, were also included in the analyses and they are nested within the clade of P. omphalodes, despite the different chemistry (protocetraric acid present versus salazinic acid in P. omphalodes). All taxa of the P. omphalodes group occupy similar niches, but their potential distributions are wider than those currently known. The absence of specimens in some localities may be limited by the photobiont availability. Parmelia omphalodes and P. pinnatifida are moderately selective in photobiont choice as they form associations with at least two or three lineages of Trebouxia clade S. Parmelia pinnatifida, as well as P. discordans are associated with Trebouxia OTU S02 which seems to have a broad ecological amplitude. Other lineages of Trebouxia seem to be rarer, especially Trebouxia sp. OTU S04, which is sometimes present in P. pinnatifida. This study indicates the importance of extensive research including morphology, chemistry and analysis of molecular markers of both bionts in taxonomical studies of lichens.

Highlights

The genus Parmelia Ach. (Parmeliaceae, Ascomycota) currently comprises ca. 40 species (Crespo and Lumbsch 2010; Thell et al 2012; Molina et al 2017) and was divided, based on the presence and type of vegetative diaspores, into three groups: the P. saxatilis group with isidiate species, the P. sulcata group containing sorediate species and the P. omphalodes group without vegetative propagules (Thell et al 2017)
335 herbarium specimens deposited in B, H, HBG, LD, S, UGDA and UPS were used for morphological, chemical and ecological niche modelling (ENM) study: 61 of P. discordans, 113 of P. pinnatifida and 161 of P. omphalodes
Specimens containing salazinic acid, but variable in fatty and lobaric acids content (Table 2), are grouped with sequences labelled as P. pinnatifida, downloaded from GenBank

Summary

Introduction

The genus Parmelia Ach. (Parmeliaceae, Ascomycota) currently comprises ca. 40 species (Crespo and Lumbsch 2010; Thell et al 2012; Molina et al 2017) and was divided, based on the presence and type of vegetative diaspores, into three groups: the P. saxatilis group with isidiate species, the P. sulcata group containing sorediate species and the P. omphalodes group without vegetative propagules (Thell et al 2017). The phylogenetic position of species of the P. omphalodes group and their taxonomic status have not been fully understood and required more detailed study as suggested by Molina et al (2004) and Thell et al (2008). The P. omphalodes group includes three taxa, often treated at the species level, i.e. P_discordans Nyl., P. omphalodes (L.) Ach. and P. pinnatifida Kurok. Hale (1987) did not agree with Skult’s concept and distinguished two species within this group, i.e. P_discordans and P. omphalodes. He did not recognise P. pinnatifida as a separate species and included it in P. omphalodes

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