Phylogenetic placement of some morphologically unusual members of Verrucariales

Abstract

Most members of Verrucariales, as in other lichenized lineages, form typical thallus morphologies, including crustose, squamulose, foliose and rarely subfruticose thalli. Some members occur in humid habitats; however some evolved unusually delicate thallus morphologies, such as minute shell-like disks, microfilamentous cushions or brittle flakes. In this study we aimed to elucidate the phylogenetic placement of such morphologically outstanding taxa. We included in our analyses Agonimia spp., Flakea papillata, Normandina spp. and Psoroglaena spp. and used a multilocus sequence dataset of the Verrucariales (SSU rDNA, LSU rDNA, mtSSU, RPB1). The resulting hypothesis revealed genus Normandina as a monophyletic group. Lauderlindsaya was confirmed as a synonym of Normandina. Normandina acroglypta is nested in N. pulchella. Psoroglaena abscondita does not cluster with other species of this genus (P. biatorella and P. stigonemoides) and is related to Verrucula and Placocarpus. Four species of Agonimia form a monophyletic group together with Norrlinia, whereas A. repleta represents its own clade. Apart from this latter relationship the phylogenetic relationship of Flakea and Normandina with other lineages in Verrucariaceae remains elusive with our multilocus dataset. More sequence data of protein-coding loci are required to increase phylogenetic resolution because morphological evolution seems to be dynamic in Verrucariales.