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

Longhorn Beetle (Xylorhiza adusta)

I find longhorn beetles exceptionally charismatic. The long antennae (although some species have short antennae) easily distinguish this group from other beetles. And it is those long antennae, the large size of certain species including some really colouful patterned ones that have enthralled generations of naturalists. The Chinese has a very apt name for longhorn beetles: 天牛. It means ‘sky cow’. The long antennae reminding them of cow horns and ‘sky’, I can only, or would rather, assume refers to the beauty of these beetles that can only be heaven sent.

Longhorns are in the family Cerambycidae with about 35,000 described species worldwide. In larval stage they are mostly wood-borers and are thus considered pests in the forestry industry, especially so in western countries where introduced Asian species are considered invasive. But in their natural habitat, longhorns have an important role in the nutrient cycle in breaking down dying or decomposing woody plants. Most species can also feed on living trees. Adults feed mostly on young leaves and twigs.

Two recent species I saw. The first is Xylorhiza adusta from Sungei Buloh. It has a wide distribution in Asia, from India to China and down to Sumatra. Known host plants include Beautyberry trees (Callicarpa arborea and C. macrophylla); plant from the mint family (Premna pyramidata); Viburnum odoratissimum and Wrightia tinctoria: both a kind of small shrubby tree. All the above plants have not been recorded in Singapore but species from the same genus can be found here.

I still can’t identify the other longhorn except that its probably Acalolepta rusticatrix. I saw it, of all places, at a pedestrian bridge along Lornie Road.

Alfred Wallace was a beetle lover and collected 132 longhorn species from Singapore. His collections form the basis of our local knowledge and today Singapore has an estimated 220 plus species although a significant number might already be nationally extinct due to habitat loss. Current information on Singapore longhorn beetles diversity is still sketchy with many knowledge gaps to be filled. A giant step forward has been taken with this website (http://www.singaporeinsects.com/index.htm) created by the industrious Cheong Loong Fah.

Pictures taken at: Lornie Road, March 2010; Sungei Buloh Wetland Reserve, June 2010.

References:

Chong, K. Y., H. T. W. Tan & R. T. Corlett, 2009. A Checklist of the Total Vascular Plant Flora of Singapore: Native, Naturalised and Cultivated Species. Raffles Museum of Biodiversity Research, National University of Singapore, Singapore. 273 pp. Uploaded 12 November 2009. http://rmbr.nus.edu.sg/raffles_museum_pub/flora_of_singapore_tc.pdf.

Duffy, E. A. J., 1968. A Monograph of the Immature Stages of Oriental Timber Beetles (Cerambycidae). British Museum (Natural History), London.

Ek-Amnuay, P., 2008. Beetles of Thailand. 2nd Edition. Amarin Printing and Publishing Public Co., Ltd, Bangkok.

Pseudagrion microcephalum; Ceriagrion cerinorubellum; Ischnura senegalensis; Pseudagrion australasiae; Podolestes orientalis; Euphaea sp.

It is easy to recognise the larvae of damselflies. Compared to a typical dragonfly larva they are slimmer and less robust. More notably, damselfly larvae have three very distinctive caudal lamellae, also called external or larval gills, at the end of the abdomen. These are absent in dragonfly larvae.

The caudal lamellae have a variety of functions. They aid in respiration, function as fins during motion and can even break off in times of escape much akin to the discarded tail of a fleeing gecko. And just like a gecko’s tail, a larva can grow back its lost lamellae. The lamellae aid, but are not essential in respiration. Thus it is not unusual to see larvae missing one, two or even all of its lamellae just like the larva of Pseudagrion microcephalum below.
The shape and size of caudal lamellae will change as a larva grows. In many species, the lamellae will become smaller relative to abdomen length but expanding in width and more tracheated, hence having a bigger role in respiration.

Size, length, shape and patterns of caudal lamellae are essential tools in identifying species. Most damselfly larvae have lamellae which are flat and vertical like those of Ceriagrion cerinorubellum, Ischnura senegalensis and Pseudagrion australasiae. The brownish spots on the lamellae of C. cerinorubellum are examples of patterns which can occur.

Meanwhile, damselflies of the Euphaea species have their caudal lamellae in the form of swollen saccoids with a terminal filament.

Recently larva of the damselfly Podolestes orientalis is described. The species is from the family Megapodagrionidae and members from this family have their caudal lamellae in a horizontal plane. This character is unique to the family although not all species in the family have horizontal lamellae. I find the fan-like shape and banded patterns of P.orientalis lamellae very eye-catching. The larvae are now known to inhabit submerged leaf litter at the edge of shallow pools where they raised their abdomen upwards and have their lamellae splayed near the water surface. In this way, horizontal lamellae may be better adapted to aid respiration near the water surface in an otherwise low oxygen leaf litter forest pool. P. orientalis is a rather common species in our forests.

The larvae of many odonate species remain unknown and undescribed. Further discoveries will help scientists shed more light on the evolutionary history of this wonderful insect group.

Pictures taken at: Ex-situ, June 2009; September 2009; October 2009

References:

Choong, C. Y. & A. G. Orr, 2010, ‘The larva of Podolestes orientalis from West Malaysia, with notes on its habitat and biology (Odonata: Megapodagrionidae)’, International Journal of Odonatology, vol. 13(1), pp. 109-117.

Corbet, P. S. & S. J. Brooks, 2008. Dragonflies. HarperCollins Publishers, London, UK.

Kalkman, V. J., C. Y. Choong, A. G. Orr & K. Shutte, 2010, ‘Remarks on the taxonomy of Megapodagrionidae with emphasis on the larval gills (Odonata)’, International Journal of Odonatology, vol. 13(1), pp. 119-135.

Orr, A. G., 2005. Dragonflies of Peninsular Malaysia and Singapore, Natural History Publications (Borneo) Sdn. Bhd, Malaysia

Brahminy Blind Snake

Nature never fails to astound me. It is not always necessary to venture into forests to see some of the most amazing creatures, they can be right here in our backyard.
A gardening session by a colleague unearthed this incredible Brahminy Blind Snake (Ramphotyphlops braminus). This is one of the smallest snakes in the world, with a total length averaging about 13cm only. It is easily mistaken for an earthworm but trained naturalists will be able to tell it doesn’t have a segmented body. Instead the body is smooth, cylindrical and on closer examination, the presence of scales. And it is much more active than an earthworm is.

Apparently it is not blind but has tiny eyes. Eyesight is not of utmost importance since this snake spends its time burrowing in the dim world of root masses and soil, hunting small insects especially ants and termites. I tried to see the eyes under a microscope. It’s a thrill to see two black minute eyes staring back.

Another amazing aspect is this species is parthenogenetic, meaning females reproducing females asexually without fertilisation of eggs by males. In fact the Brahminy Blind Snake is an all female species. This is a common reproductive strategy in insects but not so in vertebrates. Some fishes, amphibians and of course snakes are known to be parthenogenetic.

This snake is said to originate from Sri Lanka or southern India, but is now very common in most regions including Singapore thanks to our horticultural practices. Though common and widespread, its ecology hides it away from humans most of the time making this wonderfully intriguing creature a hardly seen rarity…..…unless we start digging through all garden plots.
So if you are an avid gardener, do be gentle when encountering this snake. It is harmless, can be handled safely and is deserving of a home in our gardens.

Pictures taken at: National Biodiversity Centre, December 2009.

References:

Baker, N. & K. K. P. Lim, 2008. Wild Animals of Singapore. A Photographic Guide to Mammals, Reptiles, Amphibians and Freshwater Fishes, Draco Publishing and Distribution Pte Ltd, Singapore.

Wallach, V., 2008, ‘Range extensions and new island records for Ramphotyphlops braminus (Serpentes: Typhlopidae)’, Bulletin of the Chicago Herpetological Society

, vol. 43(5), pp. 80-82.

Tetracanthagyna larva

An impressive larva I’m currently rearing has provided very fascinating insights into terrestrialism in dragonflies larvae.
This aspect of larvae ecology is rather well known. There are several studies showing larvae inhabiting small streams or seepages in forest can have a diminished dependence on water. Some species in Japan live among wet rock and mosses beside streams, a species in Himalaya hang around wet ferns near waterfalls and one species from New Caledonia clings onto the underside of moist leaves away from any water body.

Closer to home, larvae of the genus Tetracanthagyna exhibits semi-terrestrial behaviour. Tetracanthagyna degorsi from Borneo apparently leaves the water at night to perch head down near water surface, seemingly to catch surface swimming fishes. T. waterhousei is another species with similar habits. There’s a picture of its larva catching a fish while completely out of water in the Field Guide to Dragonflies of Hong Kong 2nd edition (page 211).

The larva I have now also shows identical behaviour. Its hunting strategy is ambush. Most of the time it clings out of water with only the head partially submerged. From this position it waits, and when a shrimp moves near, wham! The forceful impact of its labium capturing the hapless shrimp fatally.
After capturing, the larva will occasionally move completely out of water to consume the prey. I notice the bigger the shrimp, the more likely it’ll move above water for consumption. And this becomes more frequent as the larva grows.
Those with a phobia for things creepy and crawly will find this larva utterly hideous. It is now almost entirely black, having adapted its colour to the surroundings; it currently measures about 6cm in length; and has a dragon-like frontal appearance. It might look monstrous but once emerged into adult, it will become the biggest dragonfly in the world in terms of wingspan and weight.

Tetracanthagyna plagiata is the only species from the genus recorded in Singapore so this larva should be of the species. I didn’t have the chance to establish its gender accurately so hopefully it’ll emerge into a male as very few male specimens of T. plagiata exists in museums worldwide. It should emerge very soon as it has stopped feeding for the past few days.

Pictures taken at: ex-situ, November, December 2009 & January 2010.


References:

Corbet, P. S., 1999. Dragonflies: Behaviour and Ecology of Odonata. Cornell University Press, New York.

Norma-Rashid, Y., L. F. Cheong, H. K. Lua & D. H. Murphy, 2008. The dragonflies (Odonata) of Singapore: Current status records and collections of the Raffles Museum of Biodiversity Research. Raffles Museum of Biodiversity Research, Singapore. 24 pp. Uploaded 07 Nov 2008 [http://rmbr.nus.edu.sg/raffles_museum_pub/Dragonfly_of_Singapore.pdf]

Orr, A. G., 2003. A Guide to the Dragonflies of Borneo. Their Identification and Biology. Natural History Publications (Borneo) Sdn. Bhd, Malaysia.

Orr, A. G., 2005. Dragonflies of Peninsular Malaysia and Singapore. Natural History Publications (Borneo) Sdn. Bhd, Malaysia

Wilson, K. D. P., 2004. Field Guide to the Dragonflies of Hong Kong 2nd edn. Agriculture, Fisheries and Conservation Department, Hong Kong SAR.