A team of scientists reported the discovery of what they have named the starry dwarf frog (Astrobatrachus kurichiyana) in India's Western Ghat mountains. The team led by scientists from George Washington University and the Indian Institute of Science found it during a survey of the amphibians, snakes and lizards in the area, which is known for its intense biodiversity.
"The coloration was the first thing that stood out to me, these starry patterns with a blue tinge," team leader Seenapuram Vijayakumar of George Washington University told the press. "We hadn't seen anything like this before". The frog has an orange belly, and blue-white spots on its eyelids and jaws. Its back is dark brown, which researchers note allows it to hide in leaf litter on the forest floor. It is small enough to sit on the pad of a human thumb.
The researchers found this frog, previously unknown to science, in 2017 during a wide-reaching attempt to survey all the amphibians and reptiles in the Western Ghats by elevation, habitat, and hill range. The team logged about 30 other species the same night as the starry dwarf frog then captured another specimen the next morning. The frogs and their organs were fixed in alcohol and formaldehyde and taken back to the laboratory in Pune, where the team took high-quality CT scans of their skeletons and other anatomy.
"We used molecular sequence data to estimate the historical relationships of this ancient lineage, along with 3-dimensional micro-CT scans of the skeleton," said study co-author R. Alexander Pyron of George Washington University. "This gives us crucial information about the historical evolutionary relationships of not only Western Ghats frogs, but also of the deeper structure of the Amphibian Tree of Life".
They used both comparative anatomy and DNA analysis to determine that the starry dwarf frog is a distinct species. Molecular analysis showed it to be related to two known subfamilies, Nyctibatrachinae and Lankanectinae, though different enough to merit placement in its own subfamily, Astrobatrachinae. The team also sent CT scans from their laboratory in Pune, India to their colleagues David Blackburn and Edward Stanley of the Florida Museum of Natural History, where they used the openVertebrate project (oVert) to compare the frog's skeletal anatomy to that of other amphibians from museum collections.
"We have this deep bench of CT data that makes collections amassed over hundreds of years instantaneously available, not just to researchers, but to anyone with a computer," said Stanley. The Latin name Astrobatrachus kurichiyana refers both to the starry appearance of the frog's markings and to the local people who live in the Kurichiyarmala part of the Ghats, where the frog was discovered.