Wednesday, July 20, 2011

Neurobasis chinensis (Green Metalwing)

Local extinction. These are the two words most dreaded by Singapore’s nature conservationists. It simply means an animal or plant which used to exist in Singapore no longer does and so a part of our natural heritage is lost. In local context, an animal is presumed nationally extinct if it has not been recorded for the last 50 years.

For odonates, we have lost a few species but perhaps the greatest lost of all is the brilliantly stunning damselfly, Neurobasis chinensis (Green Metalwing). This species belongs to a damselfly group that has amazed naturalists since it was first discovered sometime in the 18th century by scientists. It’s easy to see why. The gleaming flashes of metallic green wings as the males fly along a forest stream in their repertoire of territorial and courtship behavior is a sight to marvel. So much have these damselflies capture the wonder of naturalists that a book specifically dedicated to them was published four years ago.

I’ve seen Neurobasis chinensis in Peninsular Malaysia but not really been able to take clear photographs or videos till a recent trip to Langkawi. Males of Neurobasis genus will patrol and defend territories very vigorously at sunlight spots along streams . When displaying to each other, males will reduce the beats of their hindwings thus displaying the metallic iridescent green colour in its full glory under sunshine. In this way, males would chase each other along a stream in overlapping flights, wild chases, or tight spinning circles.
Sometimes a perched male may be challenged by an intruder. When this happens, the defending male will have his abdomen raised with the tip pointing down while the intruder hovers just in front. Both males will then flash the hindwings. The video shows this behaviour and we can see why these damselflies are so enthralling to observe.

N. chinensis is extensively distributed in South and Southest Asia. It is one of about 14 species in the genus. N. chinensis can inhabit a wide variety of habitat, from unspoiled mountain forest streams to slightly disturbed lowland sandy streams. Unfortunately it was last recorded from Singapore in 1970. The last known habitat within Macritchie reservoir’s streams was destroyed due to heavy siltation during the construction and subsequent expansion of the PIE. So it is now a 41 years gap of sighting. Technically the damselfly is not presumed nationally extinct till the dreaded number hit 50 years. But researchers have thus far failed to find the species and to the best of our knowledge, habitats suitable for N. chinensis to thrive no longer exist. Impoundments of rivers for reservoirs and heavy siltation from various constructions encroaching onto our nature reserves have taken their toll. But maybe, just maybe, someone might spot it one day before the 50 years is up.

We hope some resilient population of this damselfly, fittingly dubbed “Birds of Paradise amongst Odonata”, are still hanging on somewhere in Singapore.

Pictures and video taken at: Pulau Langkawi, July 2011


Davison, G. W. H., P. K. L. Ng & H. C. Ho (eds), 2008. The Singapore Red Data Book: Threatened Plants and Animals of Singapore. 2nd Edition. The Nature Society (Singapore), Singapore

Murphy, D. H., 1997. Odonata biodiversity in the Nature Reserves of Singapore. In Proceedings of the Nature Reserves Survey Seminar. Gardens’ Bulletin Singapore. 49:333-352.

Orr, A. G. & M. Hämäläinen, 2007. The Metalwing Demoiselles (Neurobasis and Matronoides) of the Eastern Tropics: Their Identification and Biology. Natural History Publications, Borneo.

Tang, H. B., L. K. Wang & M. Hämäläinen, 2010. A Photographic Guide to the Dragonflies of Singapore. Raffles Museum of Biodiversity Research, Singapore.