Taxonomic recognition of some species-level lineages circumscribed in nominal Rhizoplaca subdiscrepans s. lat. (Lecanoraceae, Ascomycota)

Abstract

Background Rhizoplaca subdiscrepans (Nyl.) R. Sant., a saxicolous, placodioid lichen, is considered to have a worldwide distribution in warm-temperate to boreal-arctic areas in Asia, Europe and North America. However, recent studies have revealed that this species includes five unrecognized species-level lineages—‘subd A, B, C, D and E’. During research focused on the diversity of saxicolous lichens in mountainous areas of southern Poland, some interesting representatives of the genus Rhizoplaca were found. The main aim of our study was to determine the taxonomic status of the collected specimens by means of molecular tools and a comparative analysis of similar herbarium materials. Methods Detailed morphological, anatomical and chemical examinations of reference material from Asia, Europe and North and South America focused primarily on a selected group of lecanoroid taxa with a placodioid thallus. In addition, 21 new generated sequences representing Lecanora pseudomellea, Protoparmeliopsis muralis, Rhizoplaca opiniconensis, R. subdiscrepans s. lat. and R. phaedrophthalma were selected for molecular study using the internal transcribed spacer region (ITS rDNA), together with 95 available GenBank sequences mainly from the genus Rhizoplaca. Results Polish specimens that clustered with members of a potential species-level lineage ‘subd E’ of Rhizoplaca subdiscrepans complex were recovered. Comprehensive analyses of the lichen group led us to the conclusion that lineage ‘subd E’ represents R. subdiscrepans s. str. and that the taxon appears to have a limited geographical distribution and specific habitat preferences. Furthermore, some of the recently defined species candidates within R. subdiscrepans s. lat.—‘subd D’ and ‘subd A’—should be assigned to two previously known species of Rhizoplaca, namely R. opiniconensis (Brodo) Leavitt, Zhao Xin & Lumbsch and R. phaedrophthalma (Poelt) Leavitt, Zhao Xin & Lumbsch, respectively. These two species are characterized by phenotypic features observed as well in analyzed specimens representing lineages ’subd D’ and ’subd A’. Moreover, the representatives of these lineages demonstrate some differences in occupied habitat and geographical range that also correspond with the indicated species. Additionally, it was found that Lecanora pseudomellea B.D. Ryan is a strongly supported monophyletic lineage within Rhizoplaca, and therefore an appropriate new combination for the species is proposed.

Further knowledge on the lichen biota of Koryakia (Northern Kamchatka, Russia)

“…R. Sant. known from the southern part of Russian Far East (e. g., Kuznetsova et al, 2022), from which it differs by epruinose apothecia, weakly developed marginal lobes, shape of conidia (not observed in our material), and more orange tinge of thallus (McCune, 2017;Szczepańska et al, 2020). Our material generally corresponds to the description, but it contains a fatty acid and cf.…”

“…Our material generally corresponds to the description, but it contains a fatty acid and cf. isousnic acid, unlike other specimens of the species (see Szczepańska et al, 2020).…”

“…New to the Russian Far East. The nearest known locality in Russia is in Altai (Szczepańska et al, 2020). The species is related to R. subdiscrepans (Nyl.)…”

Infraspecific variation of some brown Parmeliae (in Poland) – a comparison of ITS rDNA and non-molecular characters

“…At the same time, it is necessary to include other evidence, such as chemistry, ecology, geography and morphology, for the proper delimitation of lichenised fungi species ( Hawksworth 1976 ; Dayrat 2005 ; Crespo and Pérez-Ortega 2009 ). Such careful and versatile analysis of distinct phylogenetic lineages may lead to recognising some previously-overlooked characteristics ( Kroken and Taylor 2001 ; del Prado et al 2007 ; Frolov et al 2016 ; Leavitt et al 2016 ; Szczepańska et al 2020 ). In the recent review paper, Lücking et al (2021) proposed a detailed protocol for consistent taxonomy of lichen-forming fungi.…”

“…The adequate annealing temperature was determined using the gradient method. The PCR programme consisted of an initial denaturation at 95 °C for 6 min, according to a previous study ( Szczepańska et al 2020 ), followed by 30 cycles at 95 °C for 30 sec, 51.2 °C for 45 sec, 72 °C for 45 sec, with a final extension at 72 °C for 10 min. While performing PCR, the Veriti Thermal Cycler (Life Technologies, Carlsbad, CA, USA) was used.…”