A phylogenetic reassessment of the subfamilies of Coenagrionidae (Odonata: Zygoptera)

Abstract

We reanalyzed subfamily divisions of Coenagrionidae phylogenetically using morphological characters. Characters historically and currently used to divide Coenagrionidae, as well as previously unpublished characters, were carefully defined or redefined and coded. Many characters traditionally used in coenagrionoid taxonomy were found to be continuously distributed rather than falling into discrete states. Nevertheless, it is just these characters on which most subfamily distinctions are based, we regarded it as essential to try to assess their effects in phylogenetic analysis. Therefore, character states for continuously distributed morphometric characters were determined using a clustering algorithm. We also present trees that exclude these characters, however. Cladistic analysis indicates that, of the existing subfamilies, only the apophyletic Agriocnemidinae is monophyletic. Shortest trees were markedly shorter than ones in which all current subfamilies were constrained to be monophyletic. Cladistic analysis using characters of Davies and Tobin (1984) and Fraser (1957) alone to define subfamilies resulted in poorer resolution and failed to support monophyly of any of the current subfamilies, as did alternative character weightings. Even a phenetic comparison using discriminant analysis failed to support the existing taxonomy. Our phylogeny suggests the existence of several possible clades within Coenagrionidae, but none are strongly supported by bootstrap analysis or decay index values. Coenagrionidae as a whole is polyphyletic in our shortest trees, although trees supporting amonophyletic Coenagrionidae are only slightly longer. We conclude that subfamilies should not be recognized within Coenagrionidae until well-supported subdivisions are demonstrated.