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It’s raining geckos in the Northeast

  • Credit: Dr Ishan Agarwal
    Credit: Dr Ishan Agarwal

Researchers discover eight new species of bent-toed geckos in the Northeast states of India.

The remote, biodiversity-rich landscapes of Northeast India are in the news in recent years, thanks to the discoveries of new species of animals—both big and small. After the unearthing of four new species of horned frogs, it's now time for new species of geckos to show up! In a series of collaborative studies, researchers from the Indian Institute of Science (IISc) and National Centre for Biological Sciences (NCBS), Bengaluru; Villanova University, USA; and the Natural History Museum (NHM), London, have discovered eight new species of bent-toed geckos from Northeast India.

Bent-toed geckos belong to the genus Cyrtodactylus, which is the most diverse genus of geckos with over 250 known species distributed from the Western Himalayas through Southeast Asia till Northern Australia and Papua New Guinea. As the name suggests, these geckos have slender, curved toes, unlike the typical dilated digits of other geckos. The bent-toed geckos known from Northeast India are grey or brown in colour, and are superficially similar in colouration and markings.

In the series of study, the researchers carried out a detailed taxonomic revision of previously described bent-toed geckos from the region. Taxonomy is the science of naming, defining and classifying groups of biological organisms by shared characteristics.

“This review was essential for allowing us to compare the known species with additional populations that were genetically distinct. So, only by fixing the identity of the old species, could we then accurately diagnose new ones”, says author Dr Stephen Mahony from NHM who is currently with University College Dublin.

The research, funded by the Department of Science and Technology, Ministry of Environment and Forests and the National Science Foundation, USA, was published in the journal Zootaxa in May and November 2018. The researchers described two new species of bent-toed geckos, making them the first to have been described from Northeast India and the Himalayas in over a century. Having cleared the confusions with the nomenclature, they subsequently discovered six more species of bent-toed geckos from here.

The researchers named the new species as Bhupathy’s bent-toed gecko (Cyrtodactylus bhupathyi), the Tripura bent-toed gecko (Cyrtodactylus tripuraensis), the Guwahati bent-toed gecko (Cyrtodactylus guwahatiensis), the Nagaland bent-toed gecko (Cyrtodactylus nagalandensis), the Kaziranga bent-toed gecko (Cyrtodactylus kazirangaensis), the Jaintia bent-toed gecko (Cyrtodactylus jaintiaensis), the Jampui bent-toed gecko (Cyrtodactylus montanus) and the Abhayapuri bent-toed gecko (Cyrtodactylus septentrionalis). Most of them were named after the place where they were found. C. guwahatiensis, named after the city of Guwahati, is the fifth gecko to be described from a major Indian city after two were found in Bengaluru and one each in Delhi and Mumbai. C. jaintiaensis is the largest bent-toed gecko from India, measuring over 10 cm long, excluding the tail. C. bhupathyi is named after the late herpetologist Dr Subramaniam Bhupathy, who met with a fatal accident during fieldwork in the southern Western Ghats.

The researchers used a combination of DNA analysis and physical characteristics to confirm that the geckos represented unnamed species. They surveyed in unexplored regions of the Indo-Burma biodiversity hotspot to understand more about these geckos. “What's ridiculous is that the six new species are from seven nights of surveys by 2-3 people for maybe an hour or two per night at most", recollects Dr Ishan Agarwal, lead author of the study from IISc and VU. “Myanmar has seen an incredible increase in species diversity, and it is surprising that we haven't seen a similar increase in India", he adds, noting that these discoveries are not surprising. So far, the researchers know little about the ecology, behaviour and geographic range of these species, apart from the fact that all these geckos are nocturnal and live on rocks or walls.

The hunt for these new species did not come easy! It included strenuous 45 days of exploring the difficult terrain, bad roads and sickness. “Northeast India is incredibly beautiful, and the people are great, but some of the roads were the worst we've ever driven on. I also got jaundice from eating out over two months and lost 11 kg in 2 weeks”, says Dr Agarwal recollecting the fieldwork.

The recent years have seen many discoveries of new species and changes in the classification of other species. Why is that, you ask?

“Taxonomy, like other fields of study, evolves over time as scientists agree and disagree on methods used to delimit and define new species and genera. In the past, taxonomists used physical similarities to group populations into species, species into genera, and so on. With the advent of molecular phylogenetics, which looks at how species are related based on their ancestral tree, there are now many changes in their nomenclature”, explains Dr Mahony.

The findings of these studies hold a mirror to the rich diversity in the unexplored regions of Northeast India. Many such systematic biodiversity assessments across this region could go a long way in not only discovering new species but also finding means to protect this pristine habitat.