Researchers solve case of geckos’ mistaken identity

Researchers solve case of geckos’ mistaken identity
With the identification of two new lizards, a 200-year-old taxonomic knot has been untangled

A team of researchers from the National Centre for Biological Sciences, Bengaluru (NCBS), Fergusson College, Pune, and Veer Narmad South Gujarat University, Surat, have described two new species of geckos and cleared a taxonomic mix-up that lasted for over 200 years.

The researchers undertook DNA-based research in taxonomy to figure out that these two new species had been wrongly clubbed with the so-called widespread Termite Hill Gecko (Hemidactylus Triedrus). A team led by herpetologist Zeeshan Mirza from (NCBS) and involving Gaurang Gowande (Fergusson College), Rishikesh Patil from Bengaluru, Mayuresh Ambekar (NCBS) and Harshil Patel (Veer Narmad South Gujarat University) have published their findings in the recent issue of the international journal PeerJ.

The two new species, Hemidactylus sahgali named after Bittu Sahgal (founder editor of Sanctuary Asia magazine and Sanctuary Nature Foundation) and Hemidactylus whitakeri named after Romulus Whitaker (herpetologist) have been in the wrong category so far, Mirza explains.

Hemidactylus sahgali is distributed across most parts of India spanning all over Maharashtra, Madhya Pradesh, Gujarat and Rajasthan, in addition to Karachi in Pakistan. Hemidactylus whitaker, on the other hand, is restricted to the Bengaluru-Mysuru Plateau in Southern Karnataka. Hemidactylus Triedrus is currently known from Andhra Pradesh, Karnataka, Tamil Nadu in the country and parts of Sri Lanka.

The work that began in May last year involved examining specimens across natural history museums, field work to collect tissue samples, generating micro-CT scans of the head, DNA analysis and going through a lot of literature to resolve the taxonomic mess. Hemidactylus sahgali can be easily distinguished from their look-alikes by the presence of 11–15 pored scales on their thigh whereas the other two species, H. triedrus and H. whitakeri bear 6–9 pores. “Separating the latter two was a daunting task as they were almost identical but differed in a few aspects, i.e. the number of rows and shape of the pimple-like bumpy scales on their backs. All these characters were not considered significant by previous workers but DNA data and micro-CT scan came out to our rescue and we were able to confirm that these were two different species,” Mirza said.

Harshil Patel, who is pursuing a PhD on herpetofaunal of southern Gujarat, said a common practice for naturalists and taxonomists during biodiversity surveys is to overlook subtle differences in commonly distributed species and attribute them to known species. This practice leads to unfortunate consequences of underrating a region’s biodiversity, detrimental from the point of conservation. The team is currently assessing systematics of other widespread species of snakes and lizards to identify cryptic species, which still remain undescribed.

Mirza said H. triedrus was described by three different names (H. triedrus + H. subtriedrus + H. lankae). When they did the DNA sequencing of specimens from localities of H. subtriedrus and other relevant localities, they realised that they were one species. There were two others species that were new but had been wrongly identified for so long. The study also included micro-CT scans to help delimit the three nearly identical species. “Taxonomy and DNA-based studies should go hand in hand,” said Mirza.
POLLHave you taken your vaccine shot?
Pick your favorite and click vote
4 + 2 =