PHYLOGENETIC SYSTEMATICS, TAXONOMY, AND BIOGEOGRAPHY OF JELLYFISH (CNIDARIA: MEDUSOZOA)

Abstract

The coastal shelf inhabiting box jellyfish (Cubozoa) represent the smallest class within Cnidaria with some 50 described species. A robust phylogenetic framework had been missing for Cubozoa. Herein, a molecular phylogeny for Cubozoa is presented. This phylogeny served as the basis for several taxonomic and nomenclatural changes in a reverse taxonomic approach, striving to align the classification scheme for Cubozoa with phylogenetic history. In addition, the revised classification led to a reevaluation of morphological characters used for the delineation and identification of species and higher taxa. This information was condensed into an illustrated taxonomic key to aid the identification of box jellyfish by non-specialists. Furthermore, the utility of ecological niche models for predicting the potential geographic distributions of box jellyfish based on correlations between species occurrences and environmental data was assessed. Since box jellyfish distributions are generally poorly documented, modeling approaches that make use of the limited data available may be of much value for making predictions about species distributions. Similarly, species distributions in the open oceans, in particular in the deep sea, are poorly understood and documented. A new approach to ecological niche and species distribution modeling in three dimensions was developed that has great potential for aiding studies of open ocean fauna. This new approach was used to derive an explicit a priori hypothesis about the population structure of a deep-sea inhabiting jellyfish species. In order to test this hypothesis and better understand the patterns of gene-flow in open ocean environments, population genomic data was used to evaluate population structure for this species on a global scale. The combined approach of ecological niche modeling and population genomics indicated that at least the species investigated here displays panmixia on a global scale.