Banded Phintella

Jumping Spiders are one of the most efficient hunters of insects. They have superb abilities to spring onto prey with precise accuracy. This precision is mostly thanks to their keen eyesight. The eyes arrangement is such that they have an almost 360° field of vision. Two huge front eyes give jumping spiders a telephoto-like system while eyes at the sides are akin to stereoscopic wide-angle lenses. A Banded Phintella (Phintella vittata) shows very clearly the ever vigilant eyes ready to process an all-round image, directing the spider to make the next precise jump.

I love the slight golden tinge on its carapace and abdomen. A closer look reveals a streak of blue on the femur. This makes the spider even more attractive. Using innovative experiments, local researchers have shown that females of another jumping spider species (Cosmophasis umbratica) would spend a longer time observing ultra-violet (UV+) males than UV- males regardless of which male display more actively. This suggests for that species, male UV influence plays a role in female-mate choice. Perhaps similarly, the iridescent bluish leg femora would help a male Banded Phintella in attracting the opposite sex.

Banded Phintella can be encountered at gardens as well as forested habitats.

Pictures taken at: Central Catchment Nature Reserves, February 2009

References:

Koh, K. H. J., 1989. A Guide to Common Singapore Spiders. Singapore Science Centre, Singapore.

Lim, M. L. M., J. Li & D. Li, 2008. ‘Effect of UV-reflecting markings on female mate-choice decisions in Cosmophasis umbratica, a jumping spider from Singapore’, Behavioral Ecology, vol. 19 (1), pp. 61-66.

Libellago aurantiaca (Red Jewel)

In the streams of our nature reserves lives a damselfly affectionately known as Red Jewel. This is because the males are dazzlingly colourful and in bright sunshine, the metallic reflective patches on their wings sparkle as they fly along a flowing stream.

Jewels are from the family Chlorocyphidae which consists of about 140 species worldwide, most of them distributed in Asia, Africa and Australasia. These damselflies, with the exception of the genus Rhinoneura, have their abdomen shorter than their hindwings thus separating them from other damselfly species. Another characteristic feature is the presence of an upturn snout which I feel gives them a rather cartoon-ish appearance.

Singapore has two Jewels species: the red abdomen Libellago aurantiaca and the rarer violet abdomen Libellago hyaline (Hyaline Jewel).

Red Jewels inhabit and breeds in clear swift flowing forest streams. Males are more commonly seen perching on logs or leaves on or near the water. They are highly territorial and disputes between males are settled by the most elegant way. In bright sunshine, males would confront one another hovering at almost the same spot. Facing each other but never coming into contact, these bouts of territorial displays can last for hours or as long as sunshine penetrates the forest canopy. The tangos are always conducted at sunlit spots, presumably to best showcase their striking colours.

Among Singapore’s damselfies, Jewels are perhaps most susceptible to habitat degradations. They require unpolluted swift streams for breeding and with a sedentary lifestyle, are not known to travel far from where they breed. Populations can therefore become isolated easily and some streams in our reserves have already lost their Red Jewels when the streams’ natural flow is altered by human impacts.

Conserve our fragile forest ecosystem and we’ll protect the forest’s Jewels.

Pictures and videos taken at: Central Catchment Nature Reserves, November 2008

References:

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

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

Devadatta argyoides

Competition to find a mate and reproduce the next generation is always very intense in the animal kingdom. Sometimes even a successful mating might not necessary guarantee the offsprings are sired by the original male.

Males of dragonflies and damselflies are especially adapted to displace the sperm of the previous male from a female. The discovery of sperm displacement in odonates by Prof. Jonathan Waage in 1979 is considered a significant finding in odonatology. Since then, it is now known there are four distinct ways a male can displace a rival male’s sperm: 1) physical removal by means of hooks or horns on the penis; 2) moving rivals’ sperm to sites in the females where its least likely to be used; 3) stimulation of female to induce sperm expulsion; 4) flushing out of rival’s sperm using the copulating male’s sperm.

These are fascinating behaviours. An earlier post mentioned this casually. Recently, I observed the copulation of Devadatta argyoides, enabling me a better understanding of sperm displacement.

Devadatta argyoides is from the family Amphipterygidae. This is a small and primitive family with only one species present in Peninsular Malaysia and Singapore. In fact Singapore is the type locality for this damselfly. It is rather common and usually found perching near small forest streams.

This couple had just gotten into tandem when I first spotted them. The male then flew with the female in tow for a short distance before perching above the stream. Slowly the female bent her abdomen to form the 'wheel’ thus interlocking their genitalia. Almost immediately, the male started displacing rivals’ sperm. This can be seen clearly by the male abdomen’s active movement. It lasted for about 2-3 minutes before the male stopped moving to transfer in his own sperm.

After copulation, the couple separated with the female flying off a distance away. The male did not seem interested in mate guarding nor did the female oviposit after I followed her for almost 10 minutes. I’m not familiar with the mating system of D. argyoides. Perhaps during this post-copulatory rest, the female was assessing the male’s guarding capacity, or the suitability of ovipositing site, or she’s manipulating the recently received sperm for fertilisation and evaluating its quality. The mating systems in odonates are varied with six systems currently recognised by scientists. There are lots more to discover on odonates mating behaviour especially species rarely encountered due to their elusive nature.

Pictures and video taken at: Bukit Timah Nature Reserve, October & November 2008



References:

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

Lieftinck, M. A., 1954. ‘Handlist of Malaysian Odonata’, Treubia, vol 22, pp. 1-202.

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

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.