Date Published: July 11, 2017
Publisher: Public Library of Science
Author(s): Xinli Wei, Imke Schmitt, Brendan Hodkinson, Adam Flakus, Martin Kukwa, Pradeep K. Divakar, Paul M. Kirika, Jürgen Otte, Anjuli Meiser, H. Thorsten Lumbsch, Enrico Baruffini.
Pertusarialean lichens include more than 300 species belonging to several independent phylogenetic lineages. Only some of these phylogenetic clades have been comprehensively sampled for molecular data, and formally described as genera. Here we present a taxonomic treatment of a group of pertusarialean lichens formerly known as “Pertusaria amara-group”, “Monomurata-group”, or “Variolaria-group”, which includes widespread and well-known taxa such as P. amara, P. albescens, or P. ophthalmiza. We generated a 6-locus data set with 79 OTUs representing 75 species. The distinction of the Variolaria clade is supported and consequently, the resurrection of the genus Lepra is followed. Thirty-five new combinations into Lepra are proposed and the new species Lepra austropacifica is described from mangroves in the South Pacific. Lepra is circumscribed to include species with disciform ascomata, a weakly to non-amyloid hymenial gel, strongly amyloid asci without clear apical amyloid structures, containing 1 or 2, single-layered, thin-walled ascospores. Chlorinated xanthones are not present, but thamnolic and picrolichenic acids occur frequently, as well as orcinol depsides. Seventy-one species are accepted in the genus. Although the distinction of the genus from Pertusaria is strongly supported, the relationships of Lepra remain unresolved and the genus is tentatively placed in Pertusariales incertae sedis.
Molecular data had a major impact on our understanding of the evolution and phylogenetic relationships of lichen-forming fungi, and this resulted in a dramatic change of the classification over the last decades [1–7]. Pertusarialean fungi, traditionally placed in the family Pertusariaceae, mirror these changes. Over twenty years ago one of us (HTL) became interested in this group of fungi since the delimitation of genera, especially between the two major genera Ochrolechia and Pertusaria, was unclear. At that point morphological and chemical characters suggested a complex pattern but did not allow for a clear understanding of the phylogenetic relationships in this group of lichen-forming fungi [8–10].
A total of 262 sequences of 6 gene loci were newly generated for this study, including 45 EF1α, 47 nuLSU, 43 MCM7, 48 mtSSU, 46 RPB1 and 33 TSR1 sequences. These were deposited in GenBank under accession numbers MF109133-MF109227, MF189726-MF189859and MF279153-MF279187 (S1 Table). In total, sequences of 177 samples were included in the study. The datasets used for this study were deposited in TreeBase (ID#20828). Single-locus maximum likelihood (ML) topologies are shown in the supplementary material (S1–S6 Figs). Since the ML and Bayesian trees of the concatenated, 6-locus data set (4325bp; nuLSU: 730bp, mtSSU: 741bp, RPB1: 598bp, MCM7: 554bp, EF1α: 980bp, TSR1: 722bp) were similar in their topology, only the ML trees with the posterior probabilities of the Bayesian analysis added is shown in Fig 1.