Return of a Magnificent Giant

Return of a Magnificent Giant
Species #301 - Rediscovery of the Malayan Birdwing

It was after a fruitless outing at Telok Blangah Hills Park on a Sunday morning when I decided to pay an 'old friend' a visit. Having last been to the Alexandra Hospital Butterfly Trail some months back, I thought that I'd go check out the trail to see if there were any more Black Roses flying around the area.

When I reached the trail, I could see some butterfly activity, but the weather was cloudy, and the trail was quieter than expected. A couple of macro photographers were shooting spiders and other critters. The number of butterflies was way below the heydays of the AH Butterfly Trail, where the place was busy with fluttering butterflies. I noted that some of the landscaping material had been replaced with plants that were not too attractive for butterflies. Their favourite Lantana plants were gone, as were the Heliotropium indicum. The attendant and active Leopards were also missing, as their caterpillar host plant, Salix babylonica had been removed.

I made a mental note to talk to the person in charge of the landscaping at AH to try to bring back the former glory of the trail, as far as butterflies are concerned. Alexandra Hospital is now run and managed by JurongHealth, and is the holding hospital whilst the new Ng Teng Fong Hospital is being constructed at Jurong. The new 700-bed acute care is designed with good integration of the greenery into the building fabric and features a "window for every patient" as a cutting edge ward design that departs from the conventional rectilinear wards. The hospital is scheduled for completion in 2014. CPG Consultants, the firm that I work for, are the architects for the project :)

On days where there is very little butterfly activity, I usually check out the various host plants at the trail for the early stages of butterflies. There have been times in the past where we stumbled on the caterpillars and pupae of many species. As I walked past the Aristolochia acuminata trellises, I noted that the plants were quite lush, indicating that there was low caterpillar activity. However, I noticed a few early instar and one large late instar Common Birdwing caterpillars on one of the trellises.

As I approached the other trellis, I noticed another medium-sized caterpillar on the underside of one of the large leaves of the host plant. It had curved reddish spines but was strangely speckled. Initially, I thought that it was a caterpillar of the Common Rose, but my instincts told me that this could be something different.

I noticed that the patterns on the caterpillar was indeed different from the two local Aristolochia feeding species that I was familiar with. It did not have the usual whitish-yellow saddle mark that the caterpillars of the Common Rose and Common Birdwing have.

A partially everted osmeterium of the Malayan Birdwing caterpillar

After checking my reference books and also online resources, the other species of Troides that matched the caterpillar that I found were either T. aeacus or T. amphrysus. A few references later, I managed to narrow it down to T. amphrysus as it was the only species between the two to have A. acuminata as one of its host plants.

"The earlier instars larvae usually have a rather plump appearance, constantly lack the pale "saddle 'and have dorsal tubercles that are black with orange to orange-red spines or 'thorns'. Young larvae are black with dark and pale, spineless tubercles. Those dorsally on the abdominal segment nos. 2, 3, 6 and 7 are black, and the remainder a bright orange. The penultimate instar larvae assume the 'mature' colouration and are almost coffee-brown with indistinct markings. There is no 'saddle-mark'.... Large larvae will kill smaller ones when they are present on the same host plant but in the other instances two or more equally large, grown larvae have been observed sharing the plant so that it seems the cannibalistic behaviour may be response to crowding."

(From: A Monograph of the Birdwing Butterflies, volume 2 - The genera Trogonoptera, Ripponia and Troides by J. Haugum, A. M. Low & D. Wilson.)

It was an exciting find, because thus far, the majority of our new discoveries or re-discoveries of butterfly species in Singapore had been through the observation of the adult butterflies. With the exception of the Lycaenidae and Hesperiidae that were bred successfully by ButterflyCircle members to validate the discovery/re-discovery of a species, all of the larger butterflies of the other families added to the Singapore Checklist had been through adult individuals spotted in the field.

Now I had the possibility of a re-discovery, but in the form of a caterpillar! But as I could not be absolutely sure of the identity of the adult butterfly, I continued to feed the caterpillar and watched and waited. The 3rd instar caterpillar moulted after a couple of days, and continued to eat voraciously.

Fortunately, I had cultivated a large pot of Aristolochia in my garden, and hence had adequate supply of fresh leaves for the hungry caterpillar. Almost a week later, it moulted to its 5th and final instar. By this time, the caterpillar had grown to about 90mm long, and was large and heavy. It fed intermittently, but was most active at night.

The Malayan Birdwing caterpillar in its pre-pupation pose. Note the black girdle attached to the stem of the host plant

About two and a half weeks after I discovered the caterpillar, it settled down on a strong stem of the host plant and curled up in its pre-pupation pose. It stayed in that position for over 36 hours and then pupated in the early hours of the morning. The large pupa had the usual Papilionidae girdle and was positioned upright.

After a few days I checked on the pupa, and it wriggled as it sensed something was near. The normal pupation period for many of the Troides spp can range from 12 days to as long as 20 days, so I waited in anticipation for the eclosion, with the hope that the caterpillar was not parasited! I checked on the pupa from time to time over the week or so, and each time I moved its perch, it wriggled violently making 'shuffling' sounds that was clearly audible. It wasn't exactly a squeak as reported in some literature, but definitely loud enough to scare a curious predator off.

"The pupa is usually prominently marked with grey to greenish or brownish green lines... Male pupae are around 5.2 cm long and female pupae measure about 5.8 cm in length. Pupae are capable of sound-production, a distinctly hissing sound is heard when they are disturbed. It is to prevent them from parasitized. The duration of pupal stage lasts about 3 to 4 weeks from Sumatra breeding results. Dupont mentioned that a duration of 15 to 16 days, whilst a Malay Peninsular record mentions exactly 17 days."

(From: A Monograph of the Birdwing Butterflies, volume 2 - The genera Trogonoptera, Ripponia and Troides by J. Haugum, A. M. Low & D. Wilson.)

After the 19th day from its pupation, the pupal shell turned semi-transparent, and I could see the pupa darken with the black forewings of the butterfly. Unfortunately, it was a weekday and I headed off to work, frustrated that I could not record its eclosion. When I returned that evening, a magnificent female Malayan Birdwing (Troides amphrysus ruficollis) greeted me.

Two shots of the Malayan Birdwing (top - male ; bottom - female) taken at Gopeng, Perak in Malaysia

The Malayan Birdwing has a recorded wingspan of up to 180mm and the females are much larger than the only other (until now) Troides species in Singapore, the Common Birdwing. The Malayan Birdwing has the veins of distal area of the forewing streaked with pale yellow or white. The black submarginal spots on the hindwing of the female are large and conjoined, whilst the hindwing of the male has a very narrow black border.

It was the final confirmation that I needed of the existence of this species in Singapore, and we record it as the re-discovery of this species in Singapore and #301 on the Singapore Checklist. Tracing the early stages of this caterpillar, I estimated that a female Malayan Birdwing visited the Aristolochia trellis at Alexandra Hospital Butterfly Trail around late January or early February, perhaps around the Lunar New Year period, and oviposited on the host plant. I was just fortunate to have stumbled upon its caterpillar and bred it successfully.

In one of his technical papers in the Malayan Nature Journal, R Morrell, one of the early authors and butterfly specialists in Malaysia and Singapore, commented that "the Malayan Birdwing was found at the Singapore Botanic Gardens from time to time during the NorthEast monsoon months of the year. He surmised that they could have crossed over from Johor"

So, whichever way the Malayan Birdwing may have come over to Singapore from Malaysia, we hope that the species will return to stay and be part of the butterfly fauna of Singapore once more.

Text by Khew SK ; Photos by Khew SK & Ellen Tan. Special thanks to ButterflyCircle member Teo TP for highlighting the references of the early stages of the Malayan Birdwing, and Keith Wolfe for confirming the ID of the caterpillar

References :

• [C&P4] The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, Malayan Nature Society.


• A Monograph of the Birdwing Butterflies (the Systematics of Ornithoptera, Troides and Related Genera): The Genera Trogonoptera, Ripponia and Troides Vol 2 by J. Haugum and A.M. Low (1985)


• ButterflyCorner.Net - Troides amphrysus

Butterfly of the Month - March 2011

Butterfly of the Month - March 2011

The Common Rose (Pachliopta aristolochiae asteris)

The month of March was a very eventful one globally , with widespread unrest in the Middle East as public protests crippled Egypt and removed its President, Hosni Mobarak, from power. The 'people power' protests spread to other countries like Bahrain and Libya. It would appear that the citizens of these countries, long oppressed by their governments, have had enough of being treated that way, and have risen in unison to overthrow the people behind years of near-dictatorial rule. May these countries and their people find peace again soon.

Over in Asia, on March 11, a massive earthquake calculated at a magnitude 9.0 on the Richter scale occurred near the north-east coast of Honshu, Japan. The devastating tsunami that followed inundated the Miyagi Prefecture, causing at least 10,000 or more deaths. The quake caused damage to the cooling systems at the Fukushima nuclear plants, causing a potential nuclear meltdown and radiation risk to the cities in the vicinity and even further afield in Asia.

Whilst the world reels from this shocking and sad news, our prayers go to the Japanese people that they would recover from this crisis and rebuild their lives.

The month of March is associated with the mineral heliotrope, also known as the Bloodstone. The classic Bloodstone is deep green chalcedony usually with red inclusions of iron oxide or red jasper, giving the stone a dark appearance with blood red spots.

By her who in March was born

No gem save bloodstone shall be worn

They will ensure her constancy

True friendship and fidelity.

- Gregorian Birthstone Poems

A newly eclosed Common Rose clings onto its pupal case.

For the month of March, we feature the spectacular swallowtail, the Common Rose (Pachliopta aristolochiae asteris). The species is moderately common in Singapore, often found in the vicinity of where its caterpillar host plants, Aristolochia spp., are found. Although the preferred local host plant is Aristolochia acuminata, which it shares with the Common Birdwing, it has also been successfully bred on other Aristolochia like A. ringens, A. foveolata and A. grandiflora.

At times, several individuals can be seen in a particular location where the butterfly flies restlessly, always on the move and stopping occasionally to feed at its favourite nectaring plants. During the day, it is always fluttering with a slow unhurried flight, displaying its aposematic warning colouration (a bright red body and red marginal spots on its hindwings) to would-be predators that it is distasteful.

The female Common Mormon mimics the Common Rose for protection from predators by exhibiting similar reddish submarginal spots and white markings on the hindwings.

A female Common Rose oviposits on its host plant, Aristolochia acuminata

In recent years, individuals of the Common Rose have been observed where the hindwings are totally black - this "variation" we call the Black Rose. It consistently appeared for some time from 2008 onwards but became rarer in recent years. The jury is still out on the status of this species. The physical appearance of this Black Rose matches the subspecies antiphus, but in some literature, it has been upgraded to a full species status - Pachliopta antiphus.

In both cases, whether it is Pachliopta aristolochiae antiphus or Pachliopta antiphus, a butterfly of such appearance originates from Borneo. If it were, then it may have been inadvertently brought over from Borneo via human agency through the import of plants, perhaps?

A pristine Black Rose perches on a branch

However, when the Black Rose appeared particularly at the Alexandra Hospital Butterfly Trail and also at the Singapore Botanic Gardens, the black individuals flew and co-existed with the normal subspecies asteris. Could the black "variant" be a morph of subspecies asteris? If it were a distinct subspecies, how then could the two different subspecies co-exist in the same locations?

The Black Rose appeared to be even more common than the Common Rose for a period of time, and then suddenly became rare again! What happened? Natural selection and an unknown evolutionary process that allowed the more 'dominant' subspecies asteris to take control again?

Upperside shot of the Black Rose

Perhaps breeding experiments would prove (or disprove) the status of antiphus. Could a male asteris mate with a female antiphus or vice versa? What would the offspring yield? This opportunity to breed the two "Roses" which were distinctively different in appearance was missed. Until the Black Rose appears again, we will just keep the postulation on the backburner.



Hence the status of the Black Rose is uncertain, and needs to be further researched before ascertaining it as a subspecies (or in some references, as a full and distinct species). So until then, we will leave it as an unsolved mystery and hopefully a job for someone to discover in the near future! In the meantime, let us just enjoy the beauty of the Common Rose.

Text by Khew SK : Photos by James Chia, Sunny Chir, Khew SK, Simon Sng, Horace Tan & Anthony Wong

Further Reading :

• Swallowtails of Singapore
• Aposematism in Butterflies

Life History of the Chocolate Pansy

Life History of the Chocolate Pansy (Junonia hedonia ida)

Butterfly Biodata:
Genus: Junonia Hübner, 1819
Species: hedonia Linnaeus, 1764
Subspecies: ida Cramer, 1775
Wingspan of Adult Butterfly: 55-60mm
Caterpillar Local Host Plants: Ruellia repens (Acanthaceae), Hemigraphis reptans (Acanthaceae)


A Chocolate Pansy displaying its upperside.


A Chocolate Pansy giving us a view of its underside.

Physical Description of Adult Butterfly:
Above, the wings are orangy brown with several indistinct but darker brown bands traversing from the costa towards the dorsum. There are two cell spots on the forewing and a prominent series of reddish brown post-discal ocelli on the hindwing. A much less prominent series of post-discal ocelli is also present on the forewing. Underneath, both fore- and hindwings are in duller brown but each has a dark stripe traversing from the costa to the dorsum. The stripes appear to be continuous across the two wings. A large white spot is present next to the stripe in space 7 of the hindwing. A post-discal series of ocelli is present on both wings, and these ocelli are yellowish brown on pristine specimens.


A Chocolate Pansy visiting flowers.


An adult Chocolate Pansy taking up its position on a leaf.

Field Observations of Butterfly Behaviour:
This species is rather common across multiple habitats in Singapore, with ubiquitous presence in nature reserves as well as urban and suburban areas. It flies in the usual gliding manner of the Junonia spp. and typically several individuals can be seen together in one location. Under sunny conditions, they have a habit of opening their wings wide to sunbathe while resting on a perch.



Early Stages:
The caterpillars of the Chocolate Pansy feed mainly on leaves of the two recorded local host plants, Ruellia repens and Hemigraphis reptans. Both plants belong to the Acanthaceae family, and occur as widespread weeds in Singapore. It is likely that more members of this family serve as the larval food plants for Chocolate Pansy.

Local host plant #1: Hemigraphis reptans.


Local host plant #2: Ruellia repens.

A mating pair of the Chocolate Pansy.

A mother Chocolate Pansy laying an egg on the underside of a leaf of Hemigraphis reptans.

The eggs of the Chocolate Pansy are laid singly on the young leaves or shoots of the host plants. The greenish egg is somewhat globular in shape but with a blunt top. Twelve raised ridges run from this top end to the base of the egg. Each egg has a diameter of about 0.75mm.

Two views of an egg of the Chocolate Pansy. Diameter: 0.75mm.


Two views of a mature egg of the Chocolate Pansy.

The egg takes about 3 days to hatch. The young caterpillar emerges by eating away part of the egg shell, and then proceeds to eat the rest of the egg shell from the outside. The initial length of the newly hatched is about 1.5mm. The cylindrical and pale yellowish body is covered with many small tubercles. Long dark setae emanate from those tubercles occurring dorso-laterally, and long whitish setae occur sub-spiracularly. The head capsule is pale yellowish with two large lateral dark patches.

Two views of a newly hatched caterpillar, length: 1.5mm.

The 1st instar caterpillar feeds on the lamina of young leaves and grows rapidly. After reaching about 3mm in 1.5 days, the caterpillar moults to the 2nd instar.

Two views of a 1st instar caterpillar, length: 2.8mm.


Two views of a 1st instar caterpillar, late in this stage, length: 3mm.

The body of the 2nd instar caterpillar is yellowish brown mainly and is darker brown on the dorsum. Moderately long and branched brownish processes run along the length of the body. Fine setae emanate from these processes and from other small tubercles on the body surface. The head capsule is yellowish to orangy brown and featuring two small dark brown lateral patches. This instar lasts about 2 days with the body length reaching about 5mm.

Two views of a 2nd instar caterpillar, newly moulted, length: 2.5mm


Two views of a 2nd instar caterpillar, late in this stage, length: 4.5mm

The 3rd instar caterpillar has proportionately longer dorso-lateral and lateral processes. The body is mostly dark brown to black, except for the posterior end which is yellowish to orangy brown. This instar takes about 2 days to complete with body length reaching about 8.5mm.

Two views of a 3rd instar caterpillar, newly moulted, length: 4.5mm.


Two views of a 3rd instar caterpillar, late in this stage, length: 8mm.


Two views of a 3rd instar caterpillar, about to moult. Inset: head capsule.

The 4th instar caterpillar closely resembles the 3rd instar caterpillar, except for the proportionately longer processes and the change to an orange base color for the head capsule. The body color is almost entirely black except for a short section of yellowish brown at the posterior end. A fair number of small white specks appear on the body surface. The 4th instar lasts 2-2.5 days with the body length reaching about 12mm.

Two views of a 4th instar caterpillar, early in this stage, length: 9mm.


Two views of a 4th instar caterpillar, late in this stage, length: 11mm.


Two views of a 4th instar caterpillar, about to moult, length: 11.5mm.

The 5th (and penultimate) instar caterpillar is similar to the 4th instar caterpillar.One discernible difference is the presence of a dense set of moderately long fine setae covering the entire body surface. This instar lasts for 2.5-3 days, and the body length increases rather dramatically and reaches up to 23.5mm.

A 5th instar caterpillar, newly moulted, length: 11mm.

Two views of a 5th instar caterpillar, early in this stage, length: 12.5mm. Inset: head capsule.


Two views of a 5th instar caterpillar, about to moult, length: 22mm.

The 6th (and final) instar caterpillar is similar to the 5th instar caterpillar but has an even denser carpet of whitish fine setae on the body surface. Upon closer examination, pitch black triangular patches, one to each body segment, can be discerned against a lighter shade of black for the body base colour. The head capsule is bright orange and has two black patches on both sides of the "face".


Two views of a 6th instar caterpillar, early in this stage, length: 23mm.


Two views of a 6th instar caterpillar, length: 36mm.

The 6th instar lasts for 4-4.5 days, and the body length reaches up to 40mm. The caterpillar ceases feeding and wanders around. Eventually it stops at a spot on the underside of a leaf, young shoot/stem and spins a silk pad from which it hangs vertically to take on the pre-pupatory pose.

A pre-pupa of the Chocolate Pansy.

The pupation event of a Chocolate Pansy caterpillar.

Pupation takes place about 0.5 days later. The pupa suspends itself from the silk pad with no supporting silk girdle. It is entirely greyish brown with a series of dorso-lateral pairs of short and pointed processes, one pair to each segment. The dorsum is sharply raised at the mesothorax. Black markings are also featured in the wing pads. Length of pupae: 18-19mm.

Three views of a pupa of the Chocolate Pansy.

Three views of a mature pupa of the Chocolate Pansy.

After about 5 days of development, the pupal skin of the mature pupa turns translucent and the pupa turns dark brown as a result. Patches of orangy brown can also be noticed in the wing pad. The adult butterfly emerges from the pupa the next day.

The eclosion event of a Chocolate Pansy caterpillar.

A newly eclosed Chocolate Pansy resting on its pupal case.

References:

• [C&P4] The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, Malayan Nature Society.
• A Field Guide to the Butterflies of Singapore, Khew S.K., Ink On Paper Communications, 2010.
  

Text by Horace Tan, Photos by Simon Sng, Federick Ho, Sunny Chir and Horace Tan