Phylogenetic Relationship of Marine Calanoid Copepods (Crustacea: Maxillopoda) Based on Morphological and Molecular Datasets from the Chennai Coast, Bay of Bengal

The present study highlights the phylogenetic relationship among calanoid copepods based on morphological and molecular data sets. Phylogenetic tree based on morphological characteristics for 32 species of calanoid copepods was constructed using taxonomic key characters. For the molecular datasets, the mitochondrial cytochrome oxidase I (mtCOI) and nuclear ribosomal RNA (18s rRNA) gene segments were sequenced. Maximum parsimony and maximum likelihood were used to construct a phylogenetic tree. The phylogenetic tree based on mtCOI and 18s rRNA was constructed for 20 and 15 species of calanoid copepods respectively. The present study emphasizes the monophyly of calanoid copepods. The comparison between morphological and molecular datasets of calanoid copepods showed that the phylogenetic tree constructed based on morphological characteristics showed similarity to that of 18s rRNA up to the family level. This suggests that the 18s rRNA is possibly the appropriate molecular marker for studying the phylogeny of calanoid copepods, while the mtCOI gene is the appropriate marker for species identification.