LEVERAGING NEW PHYLOPHENOMIC TECHNIQUES TO DISCOVER ‘HIDDEN' SUPPORT FOR AMBIGUOUS NODES IN THE ARTHROPOD TREE OF LIFE

Although many higher-level relationships throughout the Arthropoda have received congruent support in recent morphological and molecular analyses, a number of nodes remain elusive, particularly within Pancrustacea and Arachnida. In addition to new discoveries (new fossils, new character sources), existing cladistic matrices and morphological images are crucial sources of data for re-interpretation. I present several re-interpretations of historical data resulting in new phylogenetic information. First, using morphological images and descriptions of pancrustacean larval stages to code ontogenetic data into a character matrix where each semaphoront (discrete larval or adult stage) is considered an OTU. This decreases the reliance on continuous timing of developmental ‘events’, while explicitly incorporating previously ignored ontogenetic character changes into phylogenetic analyses. Second, using ontologies (strictly defined vocabularies) to formally define characters across a variety of taxa. This may prove particularly useful in identifying shared character states between Hexapoda and their crustacean sister-group, as many characters that actually are homologous were originally defined in support of a monophyletic Crustacea and sister relationship between Hexapoda and Myriapoda. Ontologies may also be leveraged to construct direct links between gene function (in model organisms) and morphology. Third, nascent technology to automate character coding from high-resolution images and historical dichotomous keys is introduced.