Genus Aneura (Marchantiophyta) in Slovenia and new potential lineages for Europe

The liverwort genus Aneura (Aneuraceae) has been the focus of many studies aimed at revealing the hidden cryptic diversity within the A. pinguis complex. In the last few years, the knowledge of its genetic heterogeneity and geographical distributions of the alleged species has notably increased. Genetic markers can be used to identify distinct taxa, resulting in a greater understanding of the diversification processes in this genus. This study investigated taxa of the genus Aneura present in Slovenia and shed light on the diversity of liverworts in the south-central part of Europe. The particular aim of this work was to use molecular methods to identify cryptic taxa and compile an up-to-date reference list of Slovenian bryophyte species with notes on their ecology. Using a standardized methodology outlined in several related studies, three plastid genetic regions (matK, trnH-psbA, trnL-trnF) and the complete nuclear ITS sequence dataset were analysed for 55 Aneura samples from different geographic regions in the country. Phylogenetic position of the specimens studied was investigated using distance and maximum likelihood methods. The genus Aneura is genetically separated into roughly 20 clades corresponding to proposed cryptic species, nine of which were confirmed for Slovenia. These were the clades A, B, C, E, G, M (previously regarded as A. maxima in Europe) and A. pinguis s. str. Additionally, two new lineages for Europe were discovered and discussed. Some accessions grouped closely with a North American taxon A. sharpii and a Southeast-Asian clade, which was first discovered in Thailand, but does not have a formal name. Several previously recorded European distinct phyletic lineages were detected in clades A, B, C and E. The monophyletic status of taxon B is unclear, as sequences from A. pellioides and accessions from Thailand were grouped within the confines of clade B. Furthermore, 20 morphological traits were selected for detailed study. Results from a morphological analysis indicate that the species differ somewhat in thallus width, thallus thickness, number of cells in the central part of the thallus, length of dorsal epidermal cells, the presence of a translucent margin and some other traits in the case of specific taxa. There were, however, many overlapping features among the clades examined. Ecological preferences in terms of suitable habitat characteristics are provided, narrowing the knowledge gap between the perceived ecological niches that these taxa occupy. The present paper outlines the taxonomic diversity and distribution of the genus Aneura in Slovenia and provides suggestions for further work.