Phylogenetic analysis and genetic similarities of Phyllidia spp. by comparing the nucleotide sequence of 16S rRNA and cytochrome c genes.

Phyllidiid nudibranchs are brightly colored gastropod molluscs, frequently encountered in coral reefs of the tropical Indo-Pacific. This study aimed to identify the phylogenetic similarities among the Phyllidia spp. The phylogenetic similarities among all the available Phyllidia spp. were studied by comparing the nucleotide sequence of 16s rRNA and cytochrome c genes (cox I). Sequences were retrieved from NCBI databases and aligned by using Geneious software. A phylogenetic tree was constructed for the retrieved sequences of Phyllidia spp. by using the neighbor-joining method on MEGA software and the pairwise distances were also calculated. The similarities among nucleotide sequences of 16s rRNA showed that the P. elegans, and P. haegeli had the highest similarities (99.92%) and the lowest similarities (99.14%) among P. haegeli and P. picta. While nucleotide sequences of cox I showed the highest similarities (99.90%) between P. elegans and P. ocellata, and the P. varicosa had the lowest similarities 99.74% with P. koehleri and P. larryi. The molecular phylogenetic analysis based on mitochondrial marker indicated a close relation between P. elegans and P. alyta in both cox I and 16s rRNA phylogenetic tree. The phylogenetic tree of 16s rRNA gene shows the P. ocellata is closely related to the clade of species P. exquisita. The available phylogenetic analysis could be useful in further studies of Phyllidiidae within Nudibranchia.