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Present communication reports the phylogenetic relationship between three groups of a marine limpet having different color banding patterns using COI sequencing. Samples were sequenced for mtDNA COI gene using universal primer. Comparative BLAST revealed that all three types were around 99.59% identical with Cellana karachiensis, first record of this species from Indian coasts. Apart from the morphological variations, the mtDNA COI gene analysis revealed around 1% nucleotide variations between these three types. The observed dissimilarity in COI sequences was possibly too little to consider these types as three different species. The derivation of amino acid positions indicated that these types could possibly be a complex of three cryptic species of C. karachiensis. The study proposes that the Oman and Indian populations of C. karachiensis might have derived by allopatric speciation due to geographical isolation. The group of these three cryptic species, sharing same habitat between themselves, possibly showed sympatric speciation.

A group of limpets, Cellana karachiensis, exhibiting phenotypic plasticity were examined from Gujarat coastline India, using molecular phylogeny. Previous examination of the COI genes established the presence of three different haplotypes X, Y and Z, while present study showed three more haplotypes X, X and Z. Thus, a total of six COI gene haplotypes, having 99.23% to 99.85% sequence similarity, were observed with variations at six sites. Bayesian phylogenetic analysis shows divergence of lineages X-Y, X-X and Z-Z. Careful observation of nucleotide alterations showed a nonrandom mutation with more A↔G and C↔T transitions between closely related species of the genus Cellana. A stretch of 17 base pair, within COI region, was marked as region with high degree of variability between species of Cellana. Results suggest that this could be the beginning of speciation, with partial or complete reproductive barrier or these are already distinct species in different stages of evolution.

The present study reports the phylogenetic relationship of six zoanthid species belonging to three genera, Isaurus, Palythoa, and Zoanthus identified using systematic computational analysis of mtDNA gene sequences. All six species are first recorded from the coasts of Kathiawar Peninsula, India. Genus: Isaurus is represented by Isaurus tuberculatus, genus Zoanthus is represented by Zoanthus kuroshio and Zoanthus sansibaricus, while genus Palythoa is represented by Palythoa tuberculosa, P. sp. JVK-2006 and Palythoa heliodiscus. Results of the present study revealed that among the various species observed along the coastline, a minimum of 99% sequence divergence and a maximum of 96% sequence divergence were seen. An interspecific divergence of 1-4% and negligible intraspecific divergence was observed. These results not only highlighted the efficiency of the COI gene region in species identification but also demonstrated the genetic variability of zoanthids along the Saurashtra coastline of the west coast of India.