92 Indian J. Fish., 62(2): 92-97, 2015 Gastropods and bivalves constitute about 98% of the total population of molluscs. Muricidae is the second largest family in the Neogastropoda and a widespread, speciose group of marine predators found in most parts of the world (Vermeij, 1996). Traditionally species under Muricidae family are identified based on shell morphology, sculpture, micro-structure, radula, anatomical characters, operculum structure and meristic counts (Rao and Rao, 1993; Rajagopal et al., 1998; Rao, 2003; Kumbhar and Rivonker, 2012). However, these morphological characteristics are prone to be influenced by environmental factors which in turn lead to misidentification of species. Accurate and unambiguous species identification is essential for biodiversity documentation, assessment and sustainable management of molluscan resources. DNA based taxonomy using sequence diversity among species can be used to identify and resolve taxonomic ambiguities including the discovery of new or cryptic species (Hebert et al., 2003a). Mitochondrial DNA (mtDNA) cytochrome c oxidase subunit I (COI) sequence is the most widely used genetic marker for species identification. The diversity of Thais species along the Indian coast has not so far been documented using molecular markers. Hence, the present study was undertaken with the objective to test the efficacy of mitochondrial COI gene in discriminating and documenting selected species of Thais from the west coast of India. Note DNA barcoding of Thais species (Family: Muricidae) from west coast of India RAVI KUMAR, A. K. JAISWAR, A. PAVAN-KUMAR. A, S. K. CHAKRABORTY S. JAHAGEERDAR AND W. S. LAKRA Central Institute of Fisheries Education (Deemed University), Versova, Andheri West, Mumbai - 400 061 Maharashtra, India e-mail: pavanannam@gmail.com ABSTRACT Accurate species identification is essential for defining biological entities for sustainable management and conservation. Species identification under the genus Thais (Mollusca: Neogastropoda: Muricidae) based on shell morphology often mystify due to the phenotype plasticity. In this study, efficiency of DNA barcodes (mitochondrial cytochrome c oxidase subunit I gene – COI gene) was tested to discriminate six species of Thais from west coast of India. The COI gene analysis revealed that the average transitional pairs (S i =56) were less than transversional pairs (S v =59) with an average ratio of 0.93. The mean intraspecific and interspecific distances were 0.09±0.011 and 0.19±0.012, respectively. The average between species distance was 2 times more than within species distance. However, the DNA barcodes were not able to discriminate all the species with high barcode gap. Further, intraspecific distance values were estimated by including reported sequences from other geographical locations to test the DNA barcode efficiency in delineating conspecific individuals across different geographical locations. Keywords: Cytochrome c oxidase subunit I gene, DNA barcoding, Gastropods,Muricidae, Thais Six species of the genus Thais representing two subfamilies of Muricidae were collected from across the west coast of India (Table 1). The specimens were provisionally identified upto genus level in the field based on reported literature (Apte, 1998; Tan and Sigurdsson, 1996a, b; Tan, 2000; Tan and Liu, 2001; Fernando and Fernando, 2002). Later, the species identification was confirmed with the help of taxonomic experts from Zoological Survey of India (ZSI), Kolkata. Foot tissue from live specimens were collected under aseptic conditions and preserved in absolute alcohol and stored at -80 0 C, for further processing. Total genomic DNA was isolated from preserved foot tissue following SDS-phenol/chloroform method as per Sambrook et al. (2001) with modifications. The COI gene was amplified with primers HCO2198 (5´-TAAACTTCAGGGTGACCAAAAAATCA-3´) and LCO1490 (5´-GGTCAACAAATCATAAAGATAT TGG-3´) (Folmer et al., 1994) in 25 μl reaction volume containing 100 ng template DNA, 10 pmol of each specific primer, 200 μM of each dNTPs, 1.0 unit of Taq DNA polymerase and 1x Taq buffer containing 1.5 mM MgCl 2 . The PCR cycling conditions were set as initial denaturation at 95 0 C for 3 min followed by 35 cycles of 94 0 C for 1min, 46 0 C for 1 min and 72 0 C for 1 min and final extension at 72 0 C.