Phylogenetic systematics of the genus Cyerce (Mollusca: Heterobranchia: Sacoglossa: Caliphyllidae) from the Pacific and Indian oceans with descriptions of nine new species

Abstract The genus Cyerce Bergh, 1870 has been a model for the study of defensive strategies, including chemical defences, ceratal autotomy, and crypsis or aposematism. Specialization on different algae and diverse genital armatures also make Cyerce a useful system for investigating speciation by host shift versus sexual selection. Here, we review the genus Cyerce in the Pacific and Indian oceans using molecular and morphological data. Two mitochondrial genes (COI and 16S) and one nuclear gene (H3) were sequenced from 154 specimens, including representatives from the Atlantic Ocean. Bayesian and maximum likelihood analyses were used to generate phylogenetic hypotheses. Species delimitation analyses performed on COI sequences recovered 17 genetically distinct Pacific and Indian Ocean species of Cyerce, 10 of which are new to science. Nine new species are named herein (C. takanoi sp. nov., C. katiae sp. nov., C. trowbridgeae sp. nov., C. blackburnae sp. nov., C. tutela sp. nov., C. basi sp. nov., C. whaapi sp. nov., C. goodheartae sp. nov., and C. liliuokalaniae sp. nov.). The 10th species, from the Red Sea, is not named due to the absence of internal anatomical data. These findings increase the species richness in Cyerce by about two-thirds, and demonstrate that even conspicuous taxa harbour considerable cryptic diversity.