Morphological and molecular analysis of the freshwater copepod Heliodiaptomus viduus (Calanoida: Diaptomidae)

Abstract

Morphological identification of the commonest Indian freshwater calanoid copepod Heliodiaptomus viduus has been facing a lot of controversies. To solve this problem, additional molecular support is needed. Hence, molecular analysis, along with morphological identification of the species using scanning electron microscopy (SEM) and optical microscopy, was carried out. The genetic distance between the intraspecific sequences in the 18SrRNA observed to be 0.000, while the interspecific distance within genus sequences varied from 0.000 to 0.002. Besides, it was noted that both the sequences (intraspecific) were present within a single clade of the phylogenetic trees with 100% bootstrap value. The genetic distance between the intraspecific sequences in the mtCOI observed to be 0.000, while the interspecific distance within genus sequences varied from 0.000 to 0.267 and lay in a separate clade in the phylogenetic tree from the within genus clade. Besides, it was noted that both the sequences (intraspecific) were present within a single clade of the phylogenetic tree with above 75% bootstrap value. Hence, the 18S rRNA (MH145356, MK457456) and mtCOI (MK621900) gene sequences of the present study are well supported the identification of H. viduus and it serves as the first molecular database besides providing morphological authentication (SEM images) of H.viduus. This combined analysis is envisioned to be helpful in selecting the ecologically and nutritionally important species for practical aquaculture

Keywords:

• Heliodiaptomus viduus
• 18S rRNA
• mtCOI
• Phylogenetic tree

Acknowledgements

The first author Mrs. M. Karthika is thankful to Bharathiar University for providing Scanning electron microscope (SEM) and necessary facilities. Also we wish to thank Dr. K. Altaff, Professor Emeritus (Zoology), The New College, Chennai for helping in species identification

Ethical approval

This article does not contain any studies with human participants or animals performed by any of the authors.

Disclosure statement

No potential competing interest was reported by the author(s).

Additional information

Funding

This work was supported by the University Grants commission, Bahadurshah Zafar Marg, New Delhi-110002 under Grant number [F1-17.1/2017-18/RGNF-2017-18-SC-TAM-39831/(SA-III/Website)].