31 October 2015

Two Skippers Added to the Singapore Checklist

Two Skippers Added to the Singapore Checklist
Featuring the Malayan Swift and Bengal Swift

The identification of some Lycaenidae and Hesperiidae from field shots is often challenging due to the very similar physical features of several species. This is made even more difficult due to the wide variation of these features amongst individuals and between different sexes.

In museum and scientific collections, it is much easier to identify and differentiate between species as comparisons amongst a number of specimens can be done systematically. Where available, male specimens can be dissected and their genitalia compared with a database of figures from reference resources. In recent times, the use of DNA sequencing can help advance the identification of specimens with greater accuracy.

However, positive identification of field photographed individuals is often a tricky business, because either the upperside or underside of an individual may not be available. Furthermore, if the butterfly photographed is a worn or tattered individual, its identification may prove almost impossible.

This is where the early stages of a butterfly can add another dimension to the accurate indentification of the species concerned. Over the years, our early stages expert, Horace Tan, has had many opportunities to breed and document the egg, caterpillar and pupa stages of a butterfly, and the adult morphology compared with reference literature.

After much scrutiny and discussion with our Malaysian expert Dr TL Seow, we have narrowed down the identification of two more species of Hesperiidae. The first is a species from the genus Caltoris. These "Swifts" are largely found in heavily-shaded forests in Singapore, and thus far, the Full Stop Swift (Caltoris cormasa), is the only species that has been identified with certainty. A recent find, is another species, Caltoris malaya (Malayan Swift).

Caterpillar and pupa of the Malayan Swift bred on Bambusae sp

The Malayan Swift is described as being dark brown with the usual spotting on the forewing. A key distinguishing factor is the absence of the cell spots on the forewing. On the underside, the male is ferruginuous (or dark rusty) brown, whilst the female is ochreous (or reddish-orange) brown.

Several individuals were bred, and the specimens were examined and compared. The consistent absence of the forewing cell spots narrowed down the idenfication of the species to Caltoris malaya a species that is documented as extant in Singapore by the early authors. We record this re-discovery of the Malayan Swift (Caltoris malaya) as species #323 in the Singapore Checklist.

The next species, also a re-discovery, is the Bengal Swift (Pelopidas agna agna). This species is very similar to the more common extant species found in Singapore, the Small Branded Swift (Pelopidas mathias mathias). Differentiation between the two via field shots can be a hit-and-miss affair. However, Dr TL Seow has added his other observations to help narrow down the identification between these two species.

A female Bengal Swift perches on a blade of grass

Pelopidas mathias mathias
  • Male: FW line through cell spots cut brand variably at lower third.
  • FW spots large especially 2 and 3. Spot 2 irregularly rectangular.
  • Female: Line through cell spots generally pass close spot 1b but variable and unreliable.
  • HW ground colour uneven, marginal areas often paler with dark shading/smudges around the spots.
  • Underside is greyish-ochreous
Pelopidas agna agna
  • Male: Line through cell spots only touches lower end of brand.
  • Forewing spots often very small and spot 2 very narrow.
  • Female : Line through cell spots usually far from spot 1b but unreliable.
  • Underside ground colour is even and without obvious dark shading/smudges around the spots.
  • Underside is ochreous without a grey tinge.
Breeding of several individuals and comparison with the adult males and females strongly suggest the presence of the Bengal Swift (Pelopidas agna agna) in Singapore. However, another related species, Pelopidas lyelli which also bear a strong resemblance to the Bengal Swift, may also create some confusion. This Australian species should be looked for in Singapore where it is not impossible that it reached the shores of Singapore like the Yellow Palm Dart.

Caterpillar of the Bengal Swift

Given the comparisons and specimens from breeding documentation, we record the Bengal Swift (Pelopidas agna agna) as species #324 as a re-discovery for Singapore. Further observations will continue as to whether there are other Pelopidas species exist in Singapore.

It is likely that we will continue to discover other Hesperiidae from the lookalikes via their early stages as and when the opportunities arise. Henceforth from 2015, all bred and collected material will be submitted to the Lee Kong Chian Natural History Museum for DNA sampling and the voucher specimens documented for future comparisons when more material are available.

Text by Khew SK : Photos by Horace Tan and Khew SK

Special thanks to Horace Tan for his patience and effort in documenting the early stages of these Skipper species and to Dr TL Seow for his persistence in scrutinising the voucher specimens and coming out with additional consistent ID features for the species concerned .

References :
  • The Butterflies of The Plain Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, Malaysian Nature Society.
  • Butterflies of West Malaysia and Singapore, WA Fleming, 2nd Edition, Longmans, 1983
  • Butterflies of Thailand, Pisuth Ek-Amnuay, 2nd Edition, 2012
Special Note :
All voucher specimens, host plants and early stages collected within Parks or Nature Reserves under the jurisdiction of the National Parks Board are done with the permission of the National Biodiversity Centre Division of NParks. Specimens will be submitted to the Lee Kong Chian Natural History Museum's Lepidoptera Collection for reference.

24 October 2015

Butterfly of the Month - October 2015

Butterfly of the Month - October 2015
The Mottled Emigrant (Catopsilia pyranthe pyranthe)

A male Mottled Emigrant feeding on the flower of Bidens pilosa

The haze that enveloped much of Southeast Asia continued into the month of October 2015 and will probably go down on record as one of the worst man-made air pollution event for a long time. The prevailing south-westerly and south-easterly winds continued to blow the smoke from Indonesia's forest-burning activities towards Singapore, Malaysia, southern Thailand and even as far as the Philippines!

Regional Haze map showing the extend of the haze covering Singapore, Malaysia and Thailand and the prevailing winds

It is quite amazing that Indonesian government continues to sit back whilst their own people suffer PSI conditions reaching almost 3,000! At that number, keeping count of whatever the PSI number is, becomes totally meaningless and irrelevant. It is hoped that ASEAN will continue to put pressure on the Indonesian government to take positive action to stop this environmental carnage. Otherwise it will become a yearly affair for all its neighbours - at least until the government allows the perpetrators to burn down all its forests until there is nothing left to burn.

At the moment, there is nothing else any other neighbouring country can do, but offer assistance, grumble, complain, threaten and so on, without any resolution. The only answer to end this haze will be when the Northeast monsoons puts out the fires in Sumatra and Kalimantan. A weak government cannot do anything more than to chide its neighbours for complaining about the haze.

Over in little Singapore, it is heartening to know that there are more and more voices regarding animal welfare concerns. A fisherman was videoed baiting a hook which snared an otter. In the video clip, the squeals of distress (and probably pain) from the hooked otter made watching the whole thing even more heart-wrenching. But the amount of criticism in social media prompted the government agencies and even the police to eventually locate the fisherman. The case is still pending.

This month, we feature a common butterfly species in Singapore, the Mottled Emigrant (Catopsilia pyranthe pyranthe). The Mottled Emigrant is one of three species of the genus Catopsilia found in Malaysia and Singapore. Their common name "Emigrant" suggests that these butterflies indulge in migratory tendencies. Indeed, over the years of butterfly watching here in Singapore, at least one of the species, the Lemon Emigrant (Catopsilia pomona pomona), has been seen "migrating" in numbers across the island on one occasion.

A male Mottled Emigrant shot in flight with its wings opened, whilst courting a female

The Mottled Emigrant is greenish-white in colour. On the upperside, the forewing has a thin black apical border in the male, which is much broader in the female. There is also a hint of a black marginal border on the hindwing in the female. Both sexes have a prominent black cell end spot on the upperside of the forewing.

A mating pair of Mottled Emigrants.  Left - female, right - male

The underside of the butterfly features a series of brown transverse striations, giving the butterfly a "mottled" appearance. The underside of the closely-related Lemon Emigrant is usually clean and without this mottling. However, in some individuals of the Mottled Emigrant, this mottling is so indistinct as to cause mis-identification of this species, particularly in the field.

A close-up of the mottled markings on the underside of the wings of a Mottled Emigrant

The Mottled Emigrant is a fast-flying butterfly, often on the wing on bright sunny days, flying erratically at high speed. It is skittish, and difficult to photograph, except with it stops to feed at flowering plants, or when it is resting in the shade. It is seldom encountered with its wings opened flat.

The species does not appear to puddle at moist sandy streambanks and forest footpaths (thus far no known record in Singapore). Unlike many Pieridae, which tend to puddle, the Mottled Emigrant is more often encountered feeding on flowers in urban and sub-urban parks and gardens. The caterpillar of the Mottled Emigrant feeds mainly on its preferred host plant, the Seven Golden Candlesticks (Senna alata), which has been cultivated in many parks and natureways as a butterfly-attracting plant.

In photographs, the Mottled Emigrant may look pale greenish white to light lime green, depending on the condition of the butterfly, its surroundings, fill-flash, ambient lighting and contrast settings on the camera. Hence in the field, it may sometimes be confused with the various forms of its cousin, the Lemon Emigrant. The key distinguishing characteristic are the mottled markings on the underside of the wings.

Text by Khew SK : Photos by Khew SK, Koh CH, Loke PF, Bobby Mun, Tai LA, Benedict Tay and Mark Wong.

17 October 2015

Larval Host Plant for Butterflies: Batoko Plum

Butterflies' Larval Host Plants #4
The Batoko Plum (Flacourtia inermis)

This 4th instalment of our Butterflies' Larval Host Plants series features Flacourtia inermis, a species formerly placed under Flacourtiaceae but has recently been moved to the Salicaceae (willow family) as a result of phylogenetic analyses using DNA sequence data.The species name refers to the fact that there are no spines on the trunk (unarmed).

Plant Biodata :
Family : Salicaceae
Genus : Flacourtia
Species : inermis
Country/Region of Origin : India to Malesia
English Common Names : Batoko Plum, lovi-lovi, lobi-lobi
Other Names : Rukam Masam, 紫梅, 罗比梅
Larval Host for Butterfly Species: Phalanta phalantha phalantha (Leopard), Cupha erymanthis lotis (Rustic).

Batoko Plum is native to the India and Malesia (a floristic region which includes the Malay Peninsula, Malay Archipelago, New Guinea and Bismarck Archipelago) regions. In Singapore, it is commonly planted in parks/gardens and on roadside for shade and ornamental purposes. Elsewhere, Batoko Plum is usually cultivated as a fruit tree.

Two roadside Batoko Plum trees in Singapore.

Batoko Plum is a small to medium-sized tree that grows up 15m, with trunk up to 35cm in diameter. It features simple, alternate leaves. Each leaf is ovate-oblong to ovate-elliptic in shape, about 8-12cm long and has toothed margin. Young, emerging leaves are red in colour. As the leaves grow to its mature size, they decolorise to reddish green and finally to green. The upper leaf surface typically has a glossy appearance.

The reddish young leaves of the Batoko Plum.

Maturing leaves as the reddish coloration fades away.

A mix of leaves in all stages of development of the Batoko Plum.

Mature leaves of the Batoko Plum.

Flowers of the Batoko Plum are small, creamy yellow and occur in short racemes (simple, unbranched inflorescene) which are up to 5 cm long. These flowers are dioecious (having separate male and female flowers). The unisexual flowers attract insects to act as pollinators in the reproduction process.

Racemes of flowers of the Batoko Plum rising from the stem/branch.

Close up view of the flowers.

Fruits occur in bunches and are spherical and berry like, 2 to 2.5cm in diameter. They are initially green but turning pink to red when fully ripened. They can be eaten raw but are sour and acidic in taste. Typically they are turned into jams, preserves and syrups.

Young fruits of the Batoko Plum.

Maturing fruits of the Batoko Plum.

A bunch of ripened fruits of the Batoko Plum.

In Singapore, the Batoko Plum also serves as the larval host plant for two butterfly species: Leopard and Rustic. Both are members of the Nymphalidae family, Heliconiinae sub-family.

A Leopard butterfly.

A Rustic butterfly.

Eggs of both Leopard and Rustic are laid singly on the young shoots of the Batoko Plum. Their caterpillars feed on the young and maturing leaves, and not on the fully matured leaves.

An early instar Leopard caterpillar found on a young shoot of the Batoko Plum.

A 3rd instar Leopard caterpillar resting on a against young leaf of the Batoko Plum.

A 4th instar Leopard caterpillar on the move.

A final instar Leopard caterpillar observed in the Japanese Garden.

Typically, caterpillars of both the Leopard and Rustic butterflies choose to pupate on the underside of a leaf of the host plant.

A pupa of the Leopard found on the underside of a leaf in the western part of Singapore.

A close-up view of a pupa of the Leopard found on a roadside Batoko Plum tree.

Next time when you are out for a walk/jog in our parks, gardens, park connectors or along the road outside your house, check for the presence of the Batoko Plum. A sight of this plant usually implies the existence of a colony of Leopard butterflies in the vicinity.

  • 1001 Garden Plants in Singapore : Boo Chih Min, Kartini Omar-Hor and Ou-Yang Chow Lin, National Parks Board, 2nd Edition 2007.
  • Flacourtia inermis - Asianplant.net.
  • Chase, M. W., S. Zmarzty, M. D. Lledo, K. J. Wurdack, S. M. Swensen, & M. F. Fay. When in doubt, put it in Flacourtiaceae: a molecular phylogenetic analysis based on plastid rbcL DNA sequences. Kew Bulletin 57: 141-181, 2002
  • Flacourtia inermis, Wikipedia.
Text and Photos by Horace Tan.

10 October 2015

Two Lycaenidae to Make it 322!

Two Lycaenidae to Make it 322!
Featuring Transparent Sixline Blue and Mutal Oakblue

In my earlier update to the Singapore Checklist, we saw the inclusion of a Lycaenidae and a Hesperiidae added to the list after the species' life histories were recorded and the voucher specimens examined. This week's article introduces two more species that are not easy to identify in the field without careful scrutiny of the physical features of the butterfly.

The first species featured here is one of the Lycaenidae from the genus Nacaduba. This genus comprises several lookalike species known as the Fourline and Sixline Blues. A number of the species found in Singapore look very similar and only with careful examination of their diagnostic wing markings can one separate them. The fact that these species are also variable across different individuals and sexes can also prove challenging to identify them with a high level of confidence.

The scrutiny of many photos and specimens collected during official NParks surveys indicated that one species, the Transparent Sixline Blue (Nacaduba kurava nemana) is extant in Singapore. Over the years, this species had been mis-identifed as one of its two close cousins - the Opaque Sixline Blue and the Rounded Sixline Blue. Indeed, the species are so similarly marked that they may often be confused with each other, particularly with worn-out or tattered specimens shot in the field.

With the help of ButterflyCircle forums' resident expert, Dr Seow TL, (and many discussions on the forums), we are now confident of the existence of the Transparent Sixline Blue. Besides the ID keys described in our references, Dr Seow has also added certain key characteristics that are consistent in this species.

Voucher specimen of a male Transparent Sixline Blue showing all the typical characteristics of this species

The Transparent Sixline Blue is described to have violet blue upperside in the male with the underside markings visible through the wings by transparency. The female upperside is pale shining blue with white patches beyond the forewing cell. The underside has the post-discal striae inwardly bounded by darker lines and the space between them paler than the ground colour of the wings.

A Transparent Sixline Blue shot at Seletar Country Club's Butterfly Garden

From Dr Seow's observations, he has added the following ID keys to separate this species from the other lookalikes :

Males :

  • The termen of the forewing is fairly straight.
  • Large submarginal spots (may be band-like) with rounded or scalloped inner margins; HW submarginal spot 6 large and very often quadrate (squarish).
  • Underside forewing base not darkened.
  • Upperside markings visible through the wings by transparency (although this diagnostic feature is almost impossible to ascertain in field shots except if the butterfly is sunbathing with open wings)
Females are more difficult to ID although the general features are applicable.

We record the Transparent Sixline Blue (Nacaduba kurava nemana) as species #321 in the Singapore Checklist. In the references, four other Nacaduba species - N. pendleburyi pendleburyi, N. hermus swatipa, N. subperusia lysa and N. russelli - all very similar looking species, should be further investigated and looked for in Singapore, as they have been recorded as extant by the early authors.

The next species of interest comes from the frustratingly-difficult to identify genus, Arhopala. This genus, with over 80 recorded species in Malaysia and Singapore, often proves challenging to separate the individual species. New species are still being described when additional information becomes available. This genus would benefit greatly from DNA sequencing and a database should be collated when the opportunity arises.

After ButterflyCircle member Tan Ben Jin discovered caterpillars of an Arhopala feeding on Lithocarpus bennetii in the nature reserves back in 2010, a long debate ensued and discussions on tracing the ID of the specimen initially proved futile. A later attempt at breeding the same species on the same plant by Horace Tan yielded further voucher specimens for examination.

Even with specimens bred from the same host plant, the voucher specimens that resulted from breeding appeared to have differences between individuals that suggest the existence of more than one species! However, Dr Seow is fairly confident of the identity of the Mutal Oakblue (Arhopala muta maranda) for us to record the re-discovery of this species in Singapore.

The Mutal Oakblue is a small butterfly of about 30mm wingspan and described as shining blue on the upperside, with the marginal borders increasing from 1.5 mm to about 2.0 mm at the apical area of the forewing. The hindwing is paler and a brighter blue contrasting with the forewing in a sidelight.

Male voucher specimen of the Mutal Oakblue (Arhopala muta maranda)

The female is a shining blue with a purple tinge and broad black borders. The post-discal spots on the brown underside appear more squarish, giving it a banded appearance. The spot in space 2 of the forewing is out of line with the adjacent spots and moved towards the termen. The species is tailless.

Pupa of a male Mutal Oakblue on the night before eclosion

With the relatively conclusive evidence of voucher specimens of this species, we record the Mutal Oakblue (Arhopala muta maranda) as species #322 in the Singapore Checklist.  Further investigations continue, and it is highly likely that more species from the genus Arhopala will turn up sooner or later, depending on the availability of life history documentation and actual voucher specimens for examination.

In a forthcoming blog article, we will feature the addition of two more Hesperiidae to the Singapore Checklist after concluding early stages documentation and voucher specimens have confirmed the IDs of the skippers with a high level of confidence.

Text by Khew SK : Photos by Sunny Chir, Foo Jit Leang, Khew SK, Tan Ben Jin and Horace Tan.

Special thanks to Ben Jin for discovering the Arhopala and Horace Tan for his patience and effort in documenting the early stages of these species and to Dr TL Seow for his persistence in scrutinising the voucher specimens to identify the species with a high level of confidence, in particular the Arhopala muta maranda, which led to several dead-ends for some time.

References :

  • The Butterflies of The Plain Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, Malaysian Nature Society.
  • Butterflies of West Malaysia and Singapore, WA Fleming, 2nd Edition, Longmans, 1983
  • Butterflies of Thailand, Pisuth Ek-Amnuay, 2nd Edition, 2012

Special Note :
All voucher specimens, host plants and early stages collected within Parks or Nature Reserves under the jurisdiction of the National Parks Board are done with the permission of the National Biodiversity Centre Division of NParks. Specimens will be submitted to the Lee Kong Chian Natural History Museum's Lepidoptera Collection for reference.