Molecular phylogeny and venom characterization of Indian Scorpions

Abstract

Scorpions have always been a neglected group of arthropods from scientific inquiry point of view although they are medically important because of their venom. India has a huge diversity of scorpion fauna yet effective assessment of the available diversity has not been performed. Periodic taxonomic revisions are not undertaken and till date, archaic methods of identification are practiced. Only a handful of studies have looked at the evolutionary relationships of scorpions in India. India is the abode of ‘The Indian Red Scorpion (Hottentotta tamulus)’, a scorpion species regarded as the most venomous scorpion and medicinally very important, yet a thorough venom analysis for this species is not done. In this effect, the current study deals with three aspects, namely (1) A general overview of molecular phylogeny of scorpions in Indian peninsula using the mitochondrial barcoding gene cytochrome oxidase subunit 1 (COI), (2) population genetics and morphometric analysis of H. tamulus from regions with high rainfall, moderate rainfall and dry regions and (3) preliminary analysis to characterize venom of H.tamulus from different populations to understand population variation. Total 196 samples were collected out of which genetic analysis was successful for 67 samples. I provide first genetic characterization of Heterometrus phipsoni of the family Scorpionidae and Chiromachetes sahyadriensis of family Hormuridae along with several species from family Buthidae. Genetic analysis suggests that there are several taxonomic issues with the species of Lychas, Isometrus and Hottentotta, which are likely to harbour undescribed species. Population Genetics study was carried out by studying haplotype diversity in barcoding COI gene. In population genetics study, H.tamulus formed three groups corresponding to high rainfall area on the western side of Western Ghats, the moderate rainfall area on eastern side of Western Ghats and dry region. There are various genetic mutations in samples from different H. tamulus populations, yet they code for protein with same amino acid sequence except for a few samples. Even though there is variation in populations of H. tamulus, there seems to be presence of conserved peptides in their venom concoctions. Further investigation is required to ascertain the exact nature and composition of venom