One new genus and five new species of fan-throated lizards have been found in the drier parts of India.
Fan-throated lizards are small ground dwellers. The males flaunt a multihued, fan-shaped fold of skin on their throats during the breeding season.
Because they live in dry and barren soils, when the midday heat starts to get to them they skitter about on their rear legs.
Fan-throated lizards are restricted to parts of South Asia. Little has been known about them since the first species was reported in 1829 from India. After this, only six more species have been found: three from Nepal, two from Sri Lanka and one from India.
But V. Deepak of the Indian Institute of Science in Bangalore did not believe there could be only two species of fan-throated lizards in a country as diverse in its topography as India. So he set out to find more.
Deepak and his colleagues surveyed 81 locations scattered over 61,776 square miles (160,000 sq km) across five Indian states and a union territory.
These areas are quite varied in terms of rainfall patterns and vegetation; there are many mountains and river barriers to aid the evolution of new species, says Deepak.
"You won't realize it – they all look like dry, open habitats – but if you go across all these landscapes, which is what I did for three years, I got to know that Peninsular India is much more heterogeneous than we thought," Deepak says.
During his travels he found five new species. Three belong to Sitana, the genus known before, and two to a new genus that Deepak calls Sarada, which is the local name for fan-throated lizards.
The findings have been published in the journal Contributions to Zoology.
Armed with specimens from the field, Deepak's team then got started on identifying the features that separate one species from the other.
One such feature was the morphology, including size and colour, of the dewlap: a loose, foldable flap on the throat that becomes more vivid as males grow and become sexually mature. Females do not have dewlaps.
A male fan-throated lizard will use his dewlap to woo a would-be partner by puffing it into a fan. This is made possible by the extension of a cartilaginous structure underneath the skin.
When displaying, males climb to higher ground – like a boulder or tree branch – then arch their backs upwards and stretch out the fan.
During displays, males of the genus Sitana often bob their heads up and down, while those of Sarada shake their heads left and right.
With these new discoveries, there are now 7 species of fan-throated lizards from India and 12 from the whole of South Asia. The researchers are hopeful they will find more in other unexplored areas.
Sitana visiri (Palm leaf fan-throated lizard)
The dewlap of this species is large, extending up to 56% of the trunk's length. It is serrated on the edge and thus resembles a hand-crafted palm leaf fan called "visiri" in the language of the southernmost Indian state of Tamil Nadu, where these lizards are found. The iridescent white dewlap has a prominent sky blue streak and orange spots.
The slender-bodied S. visiri prefers lowland habitats such as sandy coasts and grassland plains. It breeds during September and October with young ones hatching in January.
Sitana spinaecephalus (Spiny-headed fan-throated lizard)
This species derives its name from the Latin word "spinae", meaning "spine", and the Greek word "cephalus", meaning "head". It refers to the enlarged, spiny scales on the back of its head.
S. spinaecephalus is adapted to a life in both lowland and higher elevations of Gujarat and Maharashtra states. It was found basking on twigs and rocks in grasslands and river beds.
It too has a large dewlap, which extends up to 45% of the length of the trunk. The dewlap is yellow with a blue stripe and brown spots.
Males display to the females from May to early June.
Sitana laticeps (Broad-headed fan-throated lizard)
This species gets its name from the Latin prefix "latus" meaning "broad" and the suffix "cep" meaning "head".
It is found in rocky terrains dotted with grasses and scrubs, at altitudes ranging from 1683 to 3051 feet (513 to 930 m) above sea level. The species is confined to the hills around the city of Pune in Maharashtra.
S. laticeps has a slightly serrated, medium-sized, off-white dewlap with a blue streak on its lower jaw. The dewlap runs along 29% of the length of the trunk. Males display perched on rocks during May, June and August.
Sarada darwini (Darwin's large fan-throated lizard)
This species is found in the grasslands and cotton fields of south Maharashtra and north Karnataka, at an altitude ranging from 1804 to 2231 feet (550 to 680 m) above sea level.
It lives in deep underground crevices and can be seen basking on tufts of grass, twigs, rocks and mounds, sometimes in pairs.
Breeding takes place in May and the newly-hatched young emerge in October.
Sexually-mature males have iridescent blue, black and orange patches with yellow stripes on their large dewlap. The orange colour extends all the way down to the belly.
The species is named after Charles Darwin, who referred to the "throat-pouch" of a fan-throated lizard in his book The Descent of Man, and Selection in Relation to Sex, to illustrate secondary sexual traits in reptiles.
Sarada superba (Superb large fan-throated lizard)
Extending along 59% of the trunk, S. superba sports the largest dewlap of all the five new species. The dewlap has elongated, overlapping scales with yellow stripes on the throat. It is a prominent, iridescent blue, followed by patches of black and orange.
The species' name comes from the Latin word "superbus", meaning "magnificent", and refers to the vibrant colours of its dewlap.
The lizard prefers high plateaus 3609 to 4265 feet (1100 to 1300 m) above sea level in southern Maharashtra. It hides among rocks and crevices.
S. superba males are highly territorial. When one spots a rival nearby, he warns it off by raising his crest: an additional flap that runs all the way down from the nape of the neck to the animal's rear.