Siphula represents a remarkable case of morphological convergence in sterile lichens

Abstract

A phylogenetic study using large subunit ribosomal DNA sequence data of several species of Siphula, representing all phenotypically recognized species groups, suggests that Siphula is not monophyletic. One lineage, including the core group related to S. ceratites and the S. decumbens group, is placed with members of the Icmadophilaceae, whereas a second distinct lineage, comprising S. complanata, S. fragilis and their relatives, has evolved within the Coccotremataceae. To accommodate these species, the new genus Parasiphula is described as new to science. Parasiphula consists of species restricted to cool to cold latitudes of the Southern Hemisphere. The results show a remarkable case of parallel evolution of lineages that have lost sexual stages and propagate via thallus fragments.