Abstract
The phylogenetic relationships and morphological diversity within European Collema s. str. species were investigated. A total of 104 new sequences (four molecular markers; mtSSU, b-tub, MCM7, and RPB2 genes) from 28 specimens were generated, and analysed and used for multi-locus phylogenetic analyses. Our results suggest that Collema is only monophyletic if Collemaglebulentum is considered part of Leptogium s. str. where it originally was described. This is supported by its paraplectenchymatous thallus. Degelius´ informal Collema "Flaccidum"- and "Nigrescens"-groups are not natural, as the "Flaccidum"-group is nested within the "Nigrescens"-group. Based on our findings, seven currently accepted Collema occur in Europe: C.flaccidum, C.subflaccidum, C.curtisporum, C.furfuraceum, C.nigrescens, C.ryssoleum, and C.subnigrescens. Collemafurfuraceum is further non-monophyletic, suggesting a need for taxonomic revision.