Meeting Abstract
The discodorid nudibranchs are a family within Doridina, characterized by a gill plume surrounding the anus and a pair of finger-like oral tentacles. Members of the discodorid genus, Rostanga (Bergh 1879), can typically be identified by their red-orange to orange coloration, which they obtain from their diet of sponges. Sponge-eating species of Rostanga possess caryophyllidia and can be found in most of the world’s oceans. Morphology and anatomy alone are often insufficient for determining evolutionary relationships within Rostanga. This project investigated the relationships of newly collected taxa in order to determine if there is undocumented diversity within Rostanga based on observed variation in coloration and the presence of caryophyllidia. In this study, we present a phylogenetic analysis of Rostanga using mitochondrial COI and 16S genes along with the nuclear H3 gene. Relationships were tested using known species of Rostanga and newly collected specimens using the outgroup Discodoris cebuensis. Additionally, we used scanning electron microscopy (SEM) to view characteristics of the radula such as shape, size, and number of teeth, and dissected specimens to determine orientation of their reproductive systems. Preliminary results indicate that some Rostanga possess morphological characters that are atypical of the genus and may not be considered a “true” Rostanga. There is some support for a grouping of true Rostanga that possess elongate outer teeth with divided tips. Increased taxon sampling, additional molecular studies, and a reevaluation of morphological characters used for description will allow for more accurate delimitation of evolutionary relationships within this group.
