Neurobasis chinensis also called Common Green Metalwing is a damselfly species that belongs to the Calopterygidae family. Known to be one of the most attractive and stunning odonates due to its metallic green hindwings in males (Choong et al., 2018), N. chinensis was the first metalwing discovered by Linnaeus in 1758 (Orr & Hämäläinen, 2007). The damselfly species from the genus Neurobasis are commonly known as metalwing. Currently, there are two species of Neurobasis in Malaysia which are Neurobasis chinensis and Neurobasis longipes (Long-legged Metalwing). Both of these species can be found in Peninsular Malaysia (Orr, 2005; Orr & Hämäläinen, 2007). However, Common Green Metalwing is absent from Borneo (Orr, 2003).
The Common Green Metalwing is widely distributed in mainland tropical Asia occurring in India, Bangladesh, Nepal, Sri Lanka, Myanmar, Thailand, Laos, Vietnam, China, Peninsular Malaysia and Sumatra (Orr, 2005; Dow, 2009). This damselfly prefers forested areas with open, swift-running streams, both in the lowlands and mountains. It loves to perch in open areas around rivers that are heavily exposed to sunlight. In addition, it adapts well to secondary and disturbed habitats (Dow, 2009). N. chinensis breeds in forested and semi-woodland streams, which are frequently found on agricultural terrain. Females lay their eggs in river-submerged plants, often between root masses, and sometimes immersing themselves completely for several minutes (Nair, 2011).
Neurobasis chinensis is a moderately broad-winged species with hindwing sizes of 30-36 mm in males and 32-38.5 mm in females (Orr & Hämäläinen, 2007). Most part of the male's hindwing is iridescent green while 3/10th part at the ends appears blackish-brown. The hindwing also consists of hyaline (clear or transparent) area at the base, usually one cell row of hyaline cells. Some of the male's hindwing can also appear with mixture of green and blue depending on the angle of light.
The females can be distinguished from the males by hyaline forewings and hindwings with pale brownish veins on both wings. The membrane of the hindwings is slightly darker brown than the forewings. Each of the wings will have notable whitish nodal spots and white pseudo-pterostigmata that are always present at least in the hindwings and sometimes on the forewings (Orr & Hämäläinen, 2007).
The traits of this species, however, depend on where it is located. For instance, the male’s hindwing from South China to southern Thailand and Peninsular Malaysia is slightly narrower than Sumatra and Nias (a small island off the coast of Sumatra). Besides, the variation in females is much more obvious. In northern and central parts of Thailand (i.e. Chiang Mai), the membrane of the hindwing is distinctly darker brown than the forewing. Meanwhile, the wings are much lighter coloured in the populations of southern Thailand (from Segenting Kra in southern Thailand towards Peninsular Malaysia), with less distinction between the forewings and hindwings (Orr & Hämäläinen, 2007).
According to the IUCN Red List of Threatened Species, Common Green Metalwing has been categorised as Least Concern (Dow, 2009). Although this species can survive in disturbed areas and also on agricultural land, it could be facing some threats from human activities such as deforestation, which might degrade its aquatic habitat. For example, in Singapore, this species is considered extinct because all the suitable habitats have been destroyed (Ngiam & Cheong, 2016). Therefore, we should take early precautions to protect this species from becoming extinct for future generation.
