Monday, August 30, 2010

Singapore dragonflies & their African relatives

Three months back, I was on work assignment in Nairobi Kenya for 13 days. Most of the work time was spent in the United Nations compound. Within the huge UN complex, many artificial but well vegetated ponds exist. It thus gave me the opportunity to explore African dragonflies. Although common species in Africa, they nevertheless filled me with joy and a sense of adventure upon seeing something new. I can now make a comparison on Singapore’s dragonflies and their relatives across the Indian Ocean.
Damselflies from the genus Pseudagrion come from a large widespread subfamily Pseudagioninae. We have four species here including a very rare one, Pseudagrion rubriceps (Orange-faced Sprite) which now seems to exist only at the pond in Toa Payoh Town Park.

I saw three relatives in Nairobi. One of them is Pseudagrion salisburyense (Salisbury Sprite) that has a range from interior South Africa to east, central and western Africa.

Pseudagrion massaicum (Masai Sprite) is an extremely beautiful damselfly. Males have red eyes, orangey thorax, green markings along the abdomen and blue abdomen tip. Surely one of the most colourful damselfly I’ve seen.

The last Pseudagrion species can’t be identified with certainty. Its either P. spernatum or P. kersteni.
Ceriagrion is another large genus but only two species are in Singapore. Ceriagion chaoi (Fiery Coraltail) in Singapore is very much like Ceriagrion glabrum (Common Citril) from Africa. Their colour scheme is very similar but C. chaoi has a brighter red abdomen and olive thorax.

Dragonflies of the genus Trithemis are from the subfamily Trithemistinae or commonly called Dropwings. There are more than 50 Trithemis species worldwide, and they are essentially African but five have made it to Asia. Singapore has three species. One example is Trithemis festiva (Indigo Dropwing). Here, this species is predominately stream loving and have adapted very well to large canals and storm drains.

In the UN compound, I observed four species, one more than the whole of Singapore. The four are: Trithemis arteriosa (Red-veined Dropwing), Trithemis cf. dorsalis (Dorsal Dropwing), Trithemis stictica (Jaunty Dropwing) and the prettiest of the lot Trithemis kirbyi (Kirby’s Dropwing).

The widespread genus Brachythemis is from the subfamily Sympetrinae. Singapore has one representative, Brachythemis contaminata (Common Amberwing). Wherever B. contaminata occurs, they are always in great numbers and have a habit of flying close to the ground especially the females and immature males.

In Africa, Brachythemis dragonflies are also known as Groundlings. One species from Nairobi is Brachythemis leucosticta (Banded Groundling). Males have banded wings while females have clear wings.

Probably the most common dragonfly genus in Singapore is Orthetrum (subfamily Libellulinae). We have five species, all of which can be easily seen. In Asia, some Orthetrum species have evolved reddish colour in mature males. However pruinosed blue in mature males is more common in the genus, for example our Orthetrum luzonicum (Slender Blue Skimmer).

African Orthetrum species are mostly pruinosed blue Skimmers thus making their identification much more difficult compared to in Singapore. I saw one species in Nairobi, Orthetrum julia (Julia Skimmer) where an immature male has greenish thoracic markings.

Aeshnids of the genus Anax are highly territorial. While in Nairobi, I spotted one big dragonfly speeding around a pond in a patrolling flight and immediately I knew it is an Anax. Very fortunately, it perched and I got a clear picture of this handsome Anax imperator (Blue Emperor). It is positively more colourful than Singapore’s Anax guttatus (Emperor). And a bonus, an ovipositing female was sighted the next day.

Aside from those highlighted here, I observed 15 species in total. It was great to see those African relatives. There’s much more to learn on dragonflies knowledge beyond Singapore. Furthermore through these sightings I got acquainted with Klaas-Douwe B. Dijkstra and Viola Clausnitzer. Both of them are experts in African dragonflies and very friendly in helping to confirm the species. Not forgetting Warwick and Michele Tarboton who generously sent me their guidebooks before I left for Kenya.

Hence local dragonfly lovers should take all opportunities to spot dragonflies beyond Singapore. Remember, there’s about 5700 species in the world!




Pictures taken at: Toa Payoh Town Park, January 2009; Venus Trail, September 2009; Nairobi Kenya, May 2010; Bishan Park, July 2010; Kranji Marsh, July 2010


References:

Silsby, J., 2001. Dragonflies of the World, CSIRO Publishing, Victoria, Australia.

Tarboton, W. R. & M. Tarboton, 2005. A Fieldguide to the Damselflies of South Africa. Privately published.

Tarboton, W. R. & M. Tarboton, 2009. South African Dragonflies. A Quick Guide. Graphic Touch Guides, South Africa