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

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.

Amphitropical variation of the algal partners of Pseudephebe (Parmeliaceae, lichenized fungi)

“…The three Pseudephebe species show no substantial differentiation with regard to photobiont use, based on haplotype distribution, Fst values and the specialization parameter d' for both ITS and RPL10A. This scenario aligns with previous reports of closely related lichenized fungi sharing the photobiont pool partially or completely (Beck et al 1998;Hestmark et al 2016;Onuţ-Brännström et al 2017;Singh et al 2017;Dal Grande et al 2018;Ossowska et al 2019) and opposes to cases in which ecological speciation drove photobiont differentiation, as in the Lichina-Rivularia symbiosis (Ortiz-Álvarez et al 2015). This is reflected in the most prevalent haplotypes 1 (ITS) and 2 (RPL10A) that are shared by the three mycobiont species across continents and regions spanning different climatic conditions.…”

“…In coherence with previous ecological and evolutionary findings on parmeliod lichens (Opanowicz and Grube 2004;Ohmura et al 2006;Fernández-Mendoza et al 2011;Leavitt et al 2015;Ossowska et al 2019), all species of the genus Pseudephebe are found in association with microalgae of the genus Trebouxia throughout their entire geographic range. More specifically, the dominant photobiont is Trebouxia S02, which belongs into the Trebouxia clade S (Leavitt et al 2015;Muggia et al 2020) as identified using phylogenetic analyses.…”

“…(Singh et al 2017), Lasallia pustullata and L. hispanica (Dal Grande et al 2018), and Parmelia omphalodes s.l. (Ossowska et al 2019). These species may be found growing in the vicinity of Pseudephebe thalli both in Mediterranean mountainous areas and at lower altitudes at higher latitudes (Barreno and Pérez-Ortega 2003;Gilbert and Purvis 2009;Stenroos et al 2016).…”

The lichen genus Parmelia Ach. in Belarus

“…От близких видов P. pinnatifida и P. discordans отличается наличием лишайниковых кислот и морфологическими особенностями псевдоцифелл. Виды P. omphalodes и P. pinnatifida содержат атранорин, лобариевую и салациновую кислоты, а таллом P. discordans -протоцетраровую кислоту (Ossowska et al, 2019). Псевдоцифеллы P. pinnatifida маргинальные и ламинальные, а у видов P. omphalodes и P. discordans только маргинальные (Ossowska et al, 2019).…”

“…Этот эпилитный вид относится к лишайникам, чьи ареалы охватывают горные и холодные регионы планеты (Ossowska et al, 2019). На территории Беларуси к таким видам относятся следующие эпилиты: Montanelia sorediata (Ach.)…”