The molecular systematics of Tritoniidae : the major events in Tritoniid evolution

The family Tritoniidae (Nudibranchia, Cladobranchia, Dendronotidae) is a cryptic group of nudibranchs known to feed on a variety of octocorals (Mcdonald and Nybakken, 1999). The family has a muddled evolutionary history and previously has had limited morphological and molecular work performed to resolve these relationships. This study examines the evolutionary history of the two largest genera, Marionia and Tritonia, by sequencing a 328bp fragment of the nuclear histone 3 gene (H3), a 658bp fragment of the mitochondrial protein coding gene cytochrome c oxidase subunit I (COI), a 454bp fragment of the mitochondrial ribosomal subunit gene (16S), and a 860bp fragment of the nuclear 28S gene. Molecular data were used for likelihood and Bayesian inference analyses to reconstruct the evolutionary history and an ancestral area reconstruction was performed to gather insight into geographic origins. Based on molecular data, Marionia and Tritonia are well-supported, monophyletic groups with ancestral origins in the Indo- Pacific.