There are more species of beetle than just about anything else on Earth — approximately 400,000 species described, with perhaps a million or more left to catalogue. Now, researchers have identified 103 new species of weevil (a tiny variety of beetle), all from a single Indonesian island.
Trigonopterus weevils are wee, egg-shaped insects, dimpled like a golf ball and blessed with a protuberant schnoz. They’re found in the thickly forested islands flecked in the tepid seas between Asia and Australia, from Sumatra out to Samoa.
Plenty of weevils had been found on either end of this range, but smack in the middle was the giant island of Sulawesi, which had only one Trigonopterus, described in the 19th century.
“We had found hundreds of species on the neighbouring islands of New Guinea, Borneo and Java — why should Sulawesi with its lush habitats remain an empty space?”, said Alexander Riedel, entomologist at Germany’s Museum of Natural History Karlsruhe and lead author on the study published this week in the journal ZooKeys, in a statement.
Riedel — collaborating with the Indonesian Institute of Sciences — decided to take a closer look at rugged island’s rainforests, conducting several field surveys on Sulawesi over a few years. The team collected a couple of thousand weevils, and then went through the long process of identifying what they were seeing.
This involved looking at key physical characteristics on the wee insects, but mostly relied on DNA “barcoding” — analysing a specific segment of DNA that differs between species.
It turns out Sulawesi has a lot more than one Trigonopterus species.
The researchers described 103 species of weevil that were entirely new to science. All of them appear pretty similar at a glance, but looking closer reveals an array of differences.
Some are long and tapered, others chunky and square, and some are shaped like a lightbulb. Many species are smooth and lustrous, but others have curious, scaly filaments on their backs, or ridges and wrinkles. They subtly vary in colour, the fuzziness of their feet, and (for males at least) the shape of their penises, apparently.
With so many new species to name, the researchers had to get creative.
Most of the species are named after a quirky physical feature, or the location where they were first found. But the team also drew inspiration from pop culture, naming one particularly small, squat, greenish species Trigonopterus yoda after a revered Jedi Master of a similar mien.
They also named a few species after characters in the Asterix comics series. Others were named after figures in Greek mythology, such as satyrs (half-beast nature spirits) and Artemis, the goddess of the hunt. Still more were named after influential biologists from history.
Some of the weevils have truly epic names, such as Trigonopterus incendium, which was found in Tanjung Api (Cape of Fire), a region that spontaneously burps flaming natural gas.
Others are decidedly more humble, such as Trigonopterus squalidulus, whose name refers to how its rough exoskeleton always gets encrusted with dirt and filth.
The diversity of Trigonopterus weevils on Sulawesi is certainly huge, and the discovery of the new species helps fill in a gap in scientists’ understanding of the evolutionary history of the beetles, which are thought to have island-hopped over millennia from Australia, exploding into dozens of species at each stop.
This prodigious “speciation” is likely caused by their flightlessness and propensity to specialise on certain plants in small ranges; it’s why most of the newly-described weevils seem to be “endemic” to the specific locations they were found.
These same old habits may actually be what puts the weevils at risk of extinction in the face of widespread deforestation on Sulawesi. Unable to fly or live outside of a sole mountain or forest patch, many of the weevils’ fates are grafted directly on the survival of their home habitats.
But for now, the first step to conserving any species is figuring out if it exists at all, so there’s far more of the island to survey. In a statement, Raden Pramesa Narakusumo, coauthor on the paper and curator of beetles at the Museum Zoologicum Bogoriense, Indonesian Research Center for Biology, notes that much of Sulawesi is yet to be explored for such small beetles.
“Our survey is not yet complete and possibly we have just scratched the surface.”