Phylogenetic Analysis of Glossodoris Nudibranchs: Cryptic Species & Chemical Sequestration

Glossodoris nudibranchs (Gastropoda: Opisthobranchia: Chromodorididae) are brightly colored sea slugs that derive their toxic chemical defenses from their sponge prey. Nudibranch tooth morphology has traditionally been used for taxonomic classification, but with recent advances in molecular systematics, many of these relationships have changed. A recent mitochondrial phylogeny of the Chromodorididae revealed the genus Glossodoris to be paraphyletic. In this study, 50 individuals comprising 18 taxa were used to build a more robust phylogenetic tree of Glossodoris. Molecular phylogenetic analyses were performed on three loci: mitochondrial COI (658 bases), mitochondrial 16S (edited: 465 bases), and nuclear 28S (edited: 851 bases). Maximum likelihood and Bayesian statistical analyses were conducted to support the previously hypothesized evolutionary relationships within Glossodoris. Preliminary results suggest multiple cryptic species nested within Glossodoris cinta. Morphological analysis of mantle dermal formations, radular structure, and reproductive systems were used to confirm the molecular phylogengy. Additionally, preexisting chemical data has been amassed and will be used to determine if more closely related Glossodoris share chemical profiles; sesterterpenoid compounds exhibit a wide range of biological properties that aid in organism defense including cytotoxicity, antimicrobial, and ichthyotoxicity. These results provide insight into the evolution of chemical defense sequestering in nudibranchs and allow for a deeper understanding of coevolution and prey choice of Glossodoris nudibranchs.