Systematics and phylogeny of the West Palaearctic representatives of subfamily Baetinae (Insecta: Ephemeroptera): combined analysis of mitochondrial DNA sequences and morphology

This study represents the first formal combined (morphological and molecular) phylogenetic analysis of the highly diversified subfamily Baetinae (sensu Kazlauskas 1972). Taxonomic sampling comprised the majority of different Palaearctic lineages within the subfamily recognised so far. The data set of 47 coded morphological characters was analysed together with the partial mitochondrial DNA cytochrome oxidase c subunit I gene (COI) sequences using parsimony and Bayesian inference. From the eight genera and species-groups investigated, three were supported as monophyletic in the analyses. The monophyly of another three genera/species-groups could not be tested because only a single species was included in the sampling. The remaining two subgenera/species-groups were recovered as paraphyletic at least using one methodological approach. A monophyletic group comprising the genera Labiobaetis + Nigrobaetis + Alainites was supported as a sister lineage to the genus Baetis s.str. Morphological characters were mapped on a cladogram, clade robustness was tested by multiple approaches and alternative views to the taxonomy of the subfamily were discussed. Intraspecific and interspecific divergences in the COI sequence were estimated for the species studied. The existence of a distinct 'barcoding gap' was not supported. Baetis rhodani and Alainites muticus exhibited unusually high values of intraspecific variability pointing to the possible existence of cryptic species.