Morphological and molecular identification of marine copepod Dioithona rigida Giesbrecht, 1896 (Crustacea:Cyclopoida) based on mitochondrial COI gene sequences, from Lakshadweep sea, India

Abstract

Morphological identification of the marine cyclopoid copepod Dioithona rigida in combination with sequencing a 645 bp fragment of mitochondrial cytochrome oxidase c subunit I (mtCOI) gene, collected from offshore waters of Kavarathi Island, Lakshadweep Sea, is presented in this study. Kiefer in 1935 classified Dioithona as a separate genus from Oithona. The main distinguishing characters observed in the collected samples, such as the presence of well-developed P5 with 2 setae, 5 segmented urosome, 12 segmented antennule, compact dagger-like setae on the inner margin of proximal segment of exopod ramus in P1–P4 and engorged portion of P1-bearing a spine, confirmed their morphology to D. rigida. A comparison of setal formulae of the exopod and endopod of D. rigida with those recorded previously by various authors are also presented here. Maximum likelihood Tree analysis exhibited the clustering of D. rigida sequences into a single clade (accession numbers KP972540.1-KR528588.1), which in contrast was 37–42% divergent from other Oithona species. Further intra-specific divergence values of 0–2% also confirmed the genetic identity of D. rigida species. Paracyclopina nana was selected as an out group displayed a diverged array. The present results distinctly differentiated D. rigida from other Oithona species.

Keywords:

• Dioithona rigida
• DNA barcoding
• Indian Ocean
• Taxonomy
• Lakshadweep Sea
• Indian Ocean

Acknowledgements

We are thankful to Head of the Department of Marine Biology, Microbiology and Biochemistry, School of Marine Sciences, Cochin University of Science and Technology for the facilities and the Department of Science and Technology and Union Territory of Lakshadweep for research permission and other logistic support and necessary facilities for undertaking the study.

Disclosure statement

The authors declare responsibility for the entire contents of this paper and have no conflicts of interest.

Funding information

We are thankful to Department of Biotechnology, Govt. of India (sanction order no. BT/PR4258/AAQ/3/575/2011 dtd. 22-08-2012), for the financial support