Mitochondrial gene sequences for molecular identification of the freshwater jellyfish <i>Limnocnida indica</i> Annandale, 1912 (Hydrozoa: Limnomedusae: Olindiidae)

The current study is the first report on the molecular characteristics of the rarely occurring medusa Limnocnida indica Annandale, 1912, a freshwater jellyfish. Its taxonomic description is based on morphological characteristics that may change depending on the environmental conditions. The most fascinating feature of this species is its erratic, unpredictable appearance, which shares a similar morphology and appears at different times and locations with a considerable interval between appearances. Nevertheless, it is unclear whether these appearances are the same species or not. The DNA marker of the species is one way to shed light on this uncertainty. To this end, the sequences of the mitochondrial genes COX1, 16S rRNA, and 12S rRNA were analyzed, compared, and reviewed with the sequences of other freshwater jellyfish to gain insight into the genetic diversity and evolutionary links of this organism. The COX1 gene had 660 bases with a GC content of 44.8%, the 16S rRNA gene had 612 bases with a GC content of 40.7% and the 12S rRNA gene had 422 bases and a GC content of 38.2%. The three genes under consideration have different nucleotide sequences compared to the other freshwater jellyfish investigated. The phylogenetic relationships inferred based on COX1 showed that the species L. indica has divergence from its congeneric species, while the analysis based on the 16S rRNA gene revealed that L. indica is related to the genus L. tanganjicae. In future research on the genetic diversity and species status of visually similar freshwater jellyfish that naturally occur at different times and places in the Western Ghats of India, the molecular data provided here on this species can be used as a relevant reference.