Vestalis amoena; Vestalis amethystina

Vestalis amoena

Among Singapore’s damselflies, species from the genus Vestalis probably have the most attractive wings. Depending on the viewing angle and reflecting sunlight, the clear wings of these damselflies can appear to sparkle with purplish iridescence. We have two species in Singapore, Vestalis amoena and Vestalis amethystina. Both species look very much alike with the same metallic green colouration. In fact, the nine species known to exist in Sundaland are so similar in appearance that even differences in wings venation, body colouration and male penis structure are too ambiguous for species recognition. The only sure way to distinguish the species is by examining the male’s anal appendages.

Vestalis amethystina

Although it seems difficult but with a good digital camera giving a close-up shot of the male’s anal appendages, it is actually rather easy to identify our two Vestalis species in the field without having to capture them. For Vestalis amoena, the appendages are less curved towards each other and appear shaped like a horseshoe.

On the other hand, Vestalis amethystina has their appendages more curved towards each other. Females can be separated by the yellow labium of V. amoena and black labium of V. amethystina.

The geographical distribution of these two species is interesting. Both of them occur together from southern Thailand, Malay Peninsula to Sumatra. But V. amoena extends into Borneo while V. amethystina does not. In Borneo a close relative V. amaryllis, not found in the Malay Peninsula or Sumatra, exists. So it seems V. amaryllis became isolated in Borneo, differentiate into an independent species and occupies an ecological niche before V. amethystina could establish itself.

In Singapore, both V. amoena and V. amethystina occupy similar habitat: flowing streams in dense forest vegetation. However V. amoena is reportedly less common than V. amethystina. This seems to be very true as I encounter V. amoena less often during regular trips into the nature reserves. One very possible reason is that V. amoena prefers larger and faster flowing streams.
As forests degradation occurs, silt and sediments become accumulated causing streams to flow slower thus making it a more suitable habitat for V. amethystina. Historical records show that V. amoena was once found in Ulu Pandan. This is a perfect case in point of how much forests we have lost and how vulnerable forest damselflies are.



Pictures taken at: Central Catchment Nature Reserve, June 2008.



References:

Laidlaw, F. F., 1931. ‘A list of the dragonflies (Odonata) of the Malay Peninsula with descriptions of new species’, Journal of the Federated Malay States Museums, Singapore, vol 16, pp. 175-233.

Lieftinck, M A., 1965. ‘The species-group of Vestalis amoena Selys, 1853, in Sundaland (Odonata, Calopterygidae)’, Tijdschrift voor Entomologie, vol 108, pp. 325-364.

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

Asian Toad

Singapore has about 24 native species of frogs and toads. The common species are of course very adapted to human landscape. They are more often heard than seen, especially after a period of heaving rainfall when males broadcast their desire for females. Occasionally though, a few individuals will stumble into our urban dwellings.

Few months back, an Asian Toad (Duttaphrynus melanostictus) made an appearance in my office. More precisely, it paid homage to a small corner. It was certainly a strange one. Throughout the whole time, it just sat there facing the wall with a contemplating look. It seemed overwhelmed by the wall and can’t decide what to do next. And it just stayed there the whole day and was so engrossed it totally ignored the mosquito sucking blood from its lower back.
There must be a scientific reason why it chose to sit at the corner throughout the day. But animals do strange things. Not all behaviour has to be explained and it is this erraticism that makes wildlife so fascinating.

Pictures taken at: National Biodiversity Centre, May 2008

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.

Drepanosticta quadrata

Damselflies from the family Platystictidae usually need close examination in particular the wings venation and anal appendages to identify the species confidently. Platysticids generally occurs in primary forests near small streams and the larvae have a distinctive disproportionately large head.
Within this family, the genus Drepanosticta is represented by eight species in Peninsular Malaysia. They usually fly close to streams, flitting within the forest understory. Both males and females typically have a blue spot at the abdomen base in which the shape of the spot can serve to identify some of the species from Peninsular Malaysia. Drepanosticta quadrata has a blue spot with a triangular pointed tip. This species was described from Singapore and according to references is known only from Singapore. This would thus make this damselfly a Singapore endemic. Even so, the website http://www.asia-dragonfly.net/ has this species as also occurring in China and Myanmar and has pictures of females from Johor. More work is perhaps needed to shed light on the true distribution of this damselfly as Albert Orr himself noted Drepanosticta spp. as data deficient with many species needing identity clarification.

Pictures taken at: Central Catchment Nature Reserve, August 2008

Update 2010Jan19th:

The blue marking on abdominal segments S8-9 is variable among species of this genus. D. quadrata is not endemic to S'pore. In fact, it is believed that D. quadrata and D. fontinalis could be the same species. (thanks Dr. Ian Choong)

References:

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., 2004. ‘Critical species of Odonata in Malaysia, Indonesia, Singapore and Brunei’, in Guardians of the Watershed. Global status of dragonflies: critical species, threat and conservation, eds, V. Clausnitzer & R. Jodicke, International Journal of Odonatology, vol 7(2), pp. 371-384.

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

Octopus species

This year is the International Year of the Reef and this coming National Day weekend, local marine lovers are having a series of talks and exhibitions to launch the event. This will be a great opportunity to highlight the amazing marine biodiversity Singapore has to the otherwise uninformed general public.

As part of the event, I’ll contribute an effort on this humble blog by drawing attention to the octopus, a creature which has always fascinated me with its amazing camouflaging abilities and known intelligence.

Octopuses can be found in a wide range of habitats. Many smaller species occur in rocky shores and coral rubbles where they forage in exposed pools during low tide periods. Most are excellent at camouflage and are able to match the colours of their surroundings with astounding dexterity. The video of this animal hunting says it all.

All octopuses use a strong neurotoxin at their salivary glands to immobilise prey when their long eight arms fan out into the nooks and crannies while hunting. The fast colour changes are presumably to camouflage it against predators although I remember reading somewhere that the changing colours are also a reflection of their ‘mood’.

Identification of octopuses to species level is not easy. Careful examination of their arm length; number of suckers; beak morphology etc is necessary. Nevertheless, small benthic dwelling inter-tidal species are from the family Octopodidae and this individual would be from the genus Octopus which most species belongs to. Many inter-tidal inhabitants are small. This octopus, with its arms fully extended, would be about the size of my two palms. For many people, all they see of octopuses is a blotch of black ink as the animal retreats into their hiding places at the first sign of danger. But any observer with patience and sensitivity will no doubt be rewarded with glimpses into the lives of our inter-tidal Singaporeans.

Happy National Day to ALL Singaporeans, big or small.

Pictures and videos taken at: A southern island of Singapore, July 2008


References:

Norman, M., 2003. Cephalopods. A World Guide. ConchBooks, Hackenheim, Germany.

Pentaceraster mammillatus

It’s been almost two months since the discovery of a new sea star record at Cyrene Reef. Led by echinoderm expert Dr. David Lane, the find of Pentaceraster mammillatus created much excitement within local marine nature lovers. Not only that, the star created a chain of events, which I can now reflect on.

I'm heartened by the discovery not just because it’s a beautiful sea star, but more so that it was made from a combined effort of nature volunteers, government officials as well as a renowned scientist. All three parties whom are stakeholders working hand in hand for the betterment of Singapore’s natural heritage. As a result, Cyrene Reef now has a higher profile and has gotten the attention of the public. This is a major step towards creating a marine protected area for a reef with truly high biodiversity but also at the same time threatened by a busy shipping industry.

Publication of a subsequent news article on this discovery means everyone want a piece of the action. Many are eager to get associated, no matter how remotely, with this sea star. Working overtime editing the many drafts to satisfy all parties, the article was successfully published within a few days. For reasons known only to the perpetrator(s), the discovery also set off a series of flaming and argument on the Internet over basic taxonomy and even on the expertise of Dr. Lane. This has now resulted in what I can only best described as an uneasy truce among people working towards the same goal of marine conservation. How can we help nature when her very guardians are at odds?

Being previously found only in waters off eastern Africa and Red Sea region, P. mammillatus has been labeled an alien species by some. This is quite possible as Cyrene Reef is situated in the middle of Singapore’s shipping lanes and where ballast water could contain species not native to Singapore. This quickly became a thorny issue and politics soon came into play. To me, the wonderment of new discoveries is a major reason why I’m a student of nature. But when human politics interferes, my enthusiasm wanes quickly. I realise this is unavoidable and is something I would have to contend with. However, as much as possible, I shall do the science and leave the politics to the policy makers.

In retrospect, P. mammillatus had not only reinforced my love for nature’s possibilities but also gained me further insights into the different shades of human nature. Humans are after all nature’s child too.

Pictures taken at: Cyrene Reef, April 2008

References:

Clark, A. M. & F. W. E. Rowe, 1971. Monograph of the Shallow-Water Indo-West Pacific Echinoderms, British Museum (Natural History), London.