Guwahati: A rare shield bug first described from the Naga Hills in 1908 has been rediscovered in Nagaland after remaining unreported from Northeast India for more than a century.
The species, identified as Parastrachia nagaensis, was found in Pfutseromi village of Phek district on March 21, 2021. Researchers collected 10 specimens during the field survey, comprising five males and five females.
The rediscovery has now been documented in the international scientific journal Zootaxa, with researchers using a combination of morphological examination and DNA analysis to confirm the species.
Researchers Swapnil S. Boyane, Dharma Rajan Priyadarsanan and Hemant V. Ghate examined the collected specimens and analysed two mitochondrial genes, COI and 16S, from one male and one female.
The genetic analysis clearly distinguished the Nagaland specimens from the closely related Parastrachia japonensis. Species-delimitation tests further supported the conclusion that the two represent separate species.
The study found approximately 2.5 per cent genetic divergence between P. nagaensis and P. japonensis. In contrast, the male and female P. nagaensis specimens showed virtually no genetic divergence, supporting their identification as the same species.
Bugs found clustered on leaves
Field observations also revealed potentially important behaviour among the insects.
Researchers found groups of three to 10 adult bugs clustered on leaves of several plant species. Smaller groups were often seen occupying individual leaves, while some specimens were recorded among leaf litter.
Such clustering could indicate gregarious and potentially subsocial behaviour in P. nagaensis. However, the researchers noted that additional observations would be necessary to establish this behaviour conclusively.
The survey did not record feeding, mating, parental care or nymphs.
Host plant yet to be confirmed
The species’ host plant remains another major gap in scientific knowledge. Researchers were unable to establish which plant the bugs depend on during the survey.
They have suggested Schoepfia jasminodora, a plant native to Northeast India, China and Japan, as a possible host. However, the proposed association remains unconfirmed and requires further field investigation.
The study also presents the first illustration of the female terminalia and spermatheca of P. nagaensis, providing additional morphological information about the species.
Researchers said the rediscovery creates opportunities for further studies into the bug’s population diversity, host plant, life cycle and potential parental-care behaviour.
The research was supported by the Department of Biotechnology, Government of India, through its Bio-resource and Sustainable Livelihoods in North-East India programme.