Understanding the evolution of phenotypical characters in the Micarea prasina group (Pilocarpaceae) and descriptions of six new species within the group

Abstract

Six new Micarea species are described from Europe. Phylogenetic analyses, based on three loci, i.e. mtSSU rDNA, Mcm7 and ITS rDNA and ancestral state reconstructions, were used to evaluate infra-group divisions and the role of secondary metabolites and selected morphological characters on the taxonomy in the M.prasina group. Two main lineages were found within the group. The Micareamicrococca clade consists of twelve species, including the long-known M.micrococca and the newly described M.microsorediata, M.nigra and M.pauli. Within this clade, most species produce methoxymicareic acid, with the exceptions of M.levicula and M.viridileprosa producing gyrophoric acid. The M.prasina clade includes the newly described M.azorica closely related to M.prasina s.str., M.aeruginoprasina sp. nov. and M.isidioprasina sp. nov. The species within this clade are characterised by the production of micareic acid, with the exception of M.herbarum which lacks any detectable substances and M.subviridescens that produces prasinic acid. Based on our reconstructions, it was concluded that the ancestor of the M.prasina group probably had a thallus consisting of goniocysts, which were lost several times during evolution, while isidia and soredia evolved independently at multiple times. Our research supported the view that the ancestor of M.prasina group did not produce any secondary substances, but they were gained independently in different lineages, such as methoxymicareic acid which is restricted to M.micrococca and allied species or micareic acid present in the M.prasina clade.

Two new Micarea species (Pilocarpaceae) from Western Europe

“…1). The highly supported M. micrococca clade consists mostly of species containing methoxymicareic acid as shown by Guzow-Krzemińska et al (2019a) and Launis et al (2019a, b). This group accommodates the newly described M. pseudotsugae, which also produces methoxymicareic acid, and this species is closely related to M. byssacea and M. laeta (1 PP, 100 BS).…”

“…Although the M. prasina group has been widely studied recently (Guzow-Krzemińska et al 2019a;Launis et al 2019a, b) and numerous new species have already been recognized, here we describe another new species belonging to this group. Figure 1 shows that the entire M. prasina group is highly supported and monophyletic (1 PP, 95 BS) and agrees with previous phylogenies based on a mtSSU marker (e.g., Czarnota & Guzow-Krzemińska 2010;Guzow-Krzemińska et al 2016) (Fig.…”

“…It belongs to the Micarea micrococca group and is most closely related to M. byssacea and M. laeta. It differs from M. byssacea mostly by the lack of Sedifolia-grey pigment (Guzow-Krzemińska et al 2019a;Launis et al 2019a, b). Micarea laeta has a granular-areolate thallus but the areoles are never subsquamulose, and the thallus is also rarely continuous (Launis et al 2019b).…”

“…Chemical compounds were studied by thin-layer chromatography (TLC) using standard methods (Orange et al 2001). The crystalline granules were observed with a compound microscope under polarized light (Launis et al 2019a, b).…”

“…The lichen genus Micarea has recently been studied intensively, and several new species have been recognized worldwide (Aptroot & Cáceres 2014;Brand et al 2014;van den Boom & Ertz 2014;Guzow-Krzemińska et al 2016van den Boom et al 2017a, b;2018;Kantvilas 2018;Launis & Myllys 2019;Launis et al 2019a, b). Two more new Micarea species from Western Europe (Belgium and the Netherlands) are described below.…”