Two new species of flies discovered in Pulau Ubin mangroves

The long-legged fly (left) and the sepsid fly.
The long-legged fly (left) and the sepsid fly.PHOTOS: RENE ONG, MAIMON HUSSIN

SINGAPORE - Two new species of flies with quirky characteristics were discovered in the mangroves of Pulau Ubin in 2018 and 2019.

While one's offspring dwells in dung, the other feeds on sandflies - a known pest and bane of many beach-goers.

The insect-gobbling fly, found in May 2018, is called the long-legged fly, and its scientific name - Trigonocera ubinensis - was inspired by the island.

For the April 2019 discovery of the new sepsid fly, or black scavenger fly, that has a faecal connection, it was a double victory.

Not only is the insect a new species, its discovery also saw the creation of an insect category, or genus, new to science. This is notable because a genus ranks above a species in the hierarchy of biological classification, said the National Parks Board (NParks).

The agency announced the twin discoveries on Ubin Day, which fell on Saturday (Sept 11). First held in 2002, Ubin Day celebrates the natural and cultural heritage of the northern island.

Both flies were found by Dr Patrick Grootaert - an NParks research fellow and head of entomology at the Royal Belgian Institute of Natural Science - while he was doing fieldwork on Pulau Ubin.

The findings underscore the rich biodiversity in Pulau Ubin, which has more than 530 known species of birds, butterflies, mammals and reptiles.

"These findings will enable NParks to update Pulau Ubin's biodiversity baseline data and its species inventory, which will contribute towards developing better management strategies for the island and planning for future research, habitat enhancement and species recovery projects," said NParks in a statement on Saturday.

The flies were discovered during a survey of insects, where traps were placed at parts of the mangroves on the island.

During the process of sorting the various insects caught, new species may be discovered, and that was what happened in 2018 and 2019.

The long-legged fly was found in the mangroves of the western side of Pulau Ubin, and the sepsid fly was discovered in the mangroves of Sungei Teris.

The sepsid fly was previously thought to be an existing scavenger fly due to its physical resemblance, but further studies showed that the fly was from a new insect category and species. The fly's larvae reside in dung, which likely comes from wild boars.

As for the long-legged fly, it was found to be a predator fly that devours smaller insects such as midges and sandflies.

NParks and researchers are excited by the discovery of a new predator fly in Pulau Ubin mangroves, because it indicates that the mangrove ecosystem is thriving, with a healthy number of insects and plants to sustain the food chain.

NParks' group director of conservation, Mr Lim Liang Jim, explained: "If you have predator flies being discovered, it is an indicator of the good health of Pulau Ubin's mangroves.

"Predators are at the top of the food chain, which means that they have a lot of prey insects to feed on, and the prey insects also have flowers, leaves and the sap of plants to feed on."

However, further surveys are needed to get a complete picture of the fly's population.