Morphology-based taxonomical studies of ascidians in India are meagre due to lack of ascidian taxonomist and limitations inherent in conventional system-based identification. The use of short fragment of mitochondrial DNA sequence is proving highly useful in identifying species in a situation where, the traditional morphology-based identification is difficult. In the present study, two adult solitary ascidians collected from the Thoothukudi coast were morphologically identified as Herdmania momus Savigny, 1816 and Microcosmus squamiger Michaelsen, 1927. The genomic DNA of these ascidians was isolated, COI gene was amplified, sequenced and submitted to the GenBank under the accession numbers KM058116, KM411616 and KJ944390. Homology search result using BLAST showed that H. momus showed 100% matched with other H. momus, while M. squamiger showed similarity with Pyura herdmani, a member of the same family Pyuridae. The phylogenetic and genetic distance was maximum in interspecies than in intraspecies. These COI sequences will allow the identification of the species through DNA barcoding technique. Here, we report for the first time the COI gene of H. momus, Savigny 1816 from the Indian coast.
