Phylogenetic position and evolutionary history of the turtle and whale barnacles (Cirripedia: Balanomorpha: Coronuloidea)

Molecular phylogenetic analysis of coronuloid taxa using the maximum likelihood estimation. Based on 12S, 16S, 18S, 28S and H3 genes (total 4705 bp). At each node, the number before the slash indicates the percentage of ML bootstrap support (1000 replicates) from RAxML analysis, number following the slash at each node indicates the Bayesian posterior probability, using MrBayes. The outgroup is Verruca stroemia, Taxonomic units are linked with doted line, hosts of barnacles are indicated. [Display omitted] • Coronuloidea and Tetraclitoidea are monophyletic sister groups. • Position of Austrobalanus as the last common ancestor of these groups is unresolved. • Cylindrical bowl or cup shape shells are homoplasious traits in the Coronuloidea. • Most coronuloids genera diverged during the Miocene. Barnacles of the superfamily Coronuloidea are obligate epibionts of various marine mammals, marine reptiles and large crustaceans. We used five molecular markers: 12S rDNA, 16S rDNA, 18S rDNA, 28S rDNA and Histone 3 to infer phylogenetic relationships among sixteen coronuloids, representing most of the recent genera of barnacles of this superfamily. Our analyses confirm the monophyly of Coronuloidea and that this superfamily and Tetraclitoidea are sister groups. The six-plated Austrobalanus clusters with these two superfamilies. Based on BEAST and ML trees, Austrobalanus is basal and sister to the Coronuloidea, but the NJ tree places Austrobalanus within the Tetraclitoidae, and in the MP tree it is sister to both Coronuloidea and Tetraclitoidae. Hence the position of Austrobalanus remains unresolved. Within the Coronuloidea we identified four clades. Chelonibia occupies a basal position within the Coronuloidea which is in agreement with previous studies. The grouping of the other clades does not conform to previous studies. Divergence time analyses show that some of the time estimates are congruent with the fossil record while some others are older, suggesting the possibility of gaps in the fossil record.