Phylogeny of the Thoracican barnacles based on 18S rDNA sequences

The phylogeny of select Thoracican barnacles was estimated from 18S rDNA sequences. Six new sequences were included, Semibalanus cariosus. Tarniosoma aquila, Balanus glandula. Balanus nubilus, Megabalanus californicus and Pollicipes polymerus. These were combined with previously published sequences from Genbank. Our maximum likelihood analysis of the data is congruent with previous morphological analyses but differs from the earlier analyses based on 18S sequences, especially in the position of lbla. We also obtained greater resolution with a gene often considered too slowly evolving to be useful at higher taxonomic levels. Sessile barnacles appear to be monophyletic, but pedunculate barnacles may not be, with the Scapelloidea being the sister taxa to the sessile ones. The Balanidae also appears to be monophyletic, while the enigmatic Heterolepidae is strongly associated with the pedunculate barnacles Lepas and Octolasmus.