Butterfly of the Month - April 2023

Butterfly of the Month - April 2023

The White Banded Flat (Celaenorrhinus asmara asmara)

A White Banded Flat sunbathing on a leaf of the Fishtail Palm 

All too soon, the fourth month of 2023 has come and almost gone. The month of April belongs to the astrological sign Aries. For those born between 21 March and 19 April, your zodiac sign is Aries. We featured Capricorn, Aquarius and Pisces in the preceding Butterfly of the Month blogposts and will now move into the next in the series. The 12 zodiac signs are Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, and Pisces.

Aries (♈︎) (Greek: Κριός, romanized: Kriós, Latin for "ram") is considered the first astrological sign in the twelve signs of the zodiac. Aries has its genesis from the God of War, Ares. He is described as, "murderous, bloodthirsty, troublemaker for mortals; and, strangely, a coward". The Roman name for Ares was Mars, which is the ruling planet of Aries.

People born under the sign of Aries are known to be aggressive leaders, with the characteristics of a street-fighter and often too belligerent for some. They are bold, independent, charismatic, confident, assertive, and powerful. This boss-like zodiac sign is usually in the lead to get things done; they are certainly not procrastinators. Aries people are full of energy and have a fearlessness about them that easily combines with their leadership abilities to make things happen.

Aries are brave in all aspects of life. When it comes to facing the unknown and taking on new challenges, Aries are extremely capable. They take on challenges without wavering and enjoy finding new thrills. However, on the negative side, they can be arrogant and confrontational and an ineffective team player. In a world of collaborations and partnerships, Aries personalities may be rather out of place.

For the month of April 2023, our feature butterfly of the month is the White Banded Flat (Celaenorrhinus asmara asmara). A recent re-discovery in early 2011, the White Banded Flat belongs to the genus Celaenorrhinus which comprises about 80 species across Asia, Africa and America. Only 10 species are known to fly in Malaysia and Singapore, and the White Banded Flat is the single representative of the genus in Singapore.

Two views of a male White Banded Flat showing the erectile hair tufts on the hind tibia

The genus is characterised in that the males have an erectile hair tuft on the hind tibia. The White Banded Flat is thus far known only from a handful of locations on Pulau Ubin. It is considered very rare, but is also very local and regularly observed at its preferred sites on Pulau Ubin. Considering the very limited sites where this species can be found, and based on the IUCN criteria, it has been classified as a Critically Endangered species in the Singapore Red Data Book 3rd Edition.

A White Banded Flat puddling on a rock

The White Banded Flat is described as uncommon but widely distributed in the lowlands of Malaysia. On the forewing above the cell spot is not continued above the radius and there is no white spot in cell 1b. The discal fascia is white and does not extend below vein 2. There are some obscure darker brown markings on the hindwings above.

Typical pose of the Pyrginae or "Flats" - perched on the underside of a leaf with its wings opened flat

Typical of the genus, the males of the White Banded Flat have erectile hair tuft on the hind tibia which gives the legs a rather hairy and unique appearance. The species is often on the wing in the early hours of the day flying rapidly from perch to perch and stopping to sunbathe in the early morning warmth. As the sun rises and temperatures rise, it reverts to the typical "flat" behaviour - flying and resting on the undersides of foliage with its wings opened flat.

Thus far, the caterpillar host plant of the White Banded Flat has yet to be ascertained in Singapore.  The known host plants from other sources include Clerodendron chinense (Lamiaceae), Justicia gendarussa (Acanthaceae) and Jasminum nervosum (Oleaceae). These plant species should be looked for in the habitat where this species frequents on Pulau Ubin.

Text by Khew SK : Photos by Chng CK, Khew SK, Loh MY, Tea Yi Kai and Anthony Wong

Re-Discovery of the White Banded Flat

Re-Discovery of the White Banded Flat

Species #298 on the Singapore Checklist

It was on one of their regular butterfly-shooting outings that ButterflyCircle members Nelson Ong and Yiming decided to take a different route to explore areas that they had not ventured before. The intention was to hopefully find something new and unrecorded.

A White Banded Flat perched on a rocky surface

Their sense of adventure and pioneering spirit was rewarded with the sighting and a few shots of a species that was extant in Singapore in the early authors' checklist, but has not been seen in recent years. What was interesting, was that they didn't just chance upon only one individual of this species, the White Banded Flat (Celaenorrhinus asmara asmara), but stumbled on a small colony of them! The skippers were observed zipping up and down a forested path, and dogfighting with other individuals of the same species, as well as other Hesperiidae species.

The shot that started all the excitement of the re-discovery of the White Banded Flat. This individual was first spotted by Yiming and Nelson

After the sighting was reported, another group of ButterflyCircle members headed for the location and observed the same behaviour in the colony of the species. At certain times of the day, the White Banded Flats were observed stopping and sunbathing on the top surfaces of leaves, almost repeating a fixed routine where they fly rapidly, and then returning to the a favourite perch to sunbathe.

A White Banded Flat checking out the flash of one of the BC members

Occasionally, they even stop on rocks in the same manner, and one even stopped on one of the photographer's camera flash, as if to check out the intruders into their territory! However, this behaviour appeared to be just for sunbathing and resting after their rapid flight. None of them were observed to be feeding on the leaves or perches, as their proboscis were not extended for feeding.

When it has had enough of sunbathing on the top surfaces of leaves, it reverts to the habit of perching on the undersides of leaves with its wings opened flat as shown in this photo

After a period of time, they reverted to the typical behaviour of the subfamily Pyrginae (Flats) whereby they stop on the undersides of leaves with their wings opened flat. Further visits and observations indicated that there was at least half a dozen or more individuals of this species in that location. However, after a period of activity and chasing each other in rapid bursts of active flight, the butterflies abruptly disappeared mysteriously altogether!

This observation is quite consistent with some species of the subfamily Pyrginae, where their active period during the day is very time-sensitive, almost like clockwork, and then beyond their magical "hour" (sometimes longer, sometimes shorter), they will mysteriously disappear suddenly, only to appear at the same time and location the following day, over a period of time.

The White Banded Flat belongs to the genus Celaenorrhinus, which occurs in the tropics of Asia, Africa and America. Some 80 species are known to exist, although only 10 are recorded in Malaysia. In the reference checklist (Ref : Corbet & Pendlebury), one species, C. asmara asmara was recorded in Singapore. However, until this recent re-discovery, the species has not been seen in Singapore over the past two decades or more.

Mr Hairy Legs! The erectile hair tuft on the hind tibia of the male of the White Banded Flat

The males of the species in the genus have erectile hair tuft on the hind tibia which gives the legs a rather hairy and unique appearance. The White Banded Flat has been described as uncommon but widely distributed in the lowlands of Malaysia. On the forewing above, the forewing cell spot is not continued above the radius and there is no white spot in cell 1b. The discal fascia is white and does not extend below vein 2. There are some obscure darker brown markings on the hindwings above.

The host plant is Clerodendrum fragrans. The caterpillar is described as stout with a short neck and a lustrous black head. It is also noteworthy that the scientific name of the species comes from the Malay word asmara which means "romance or love". Whether Butler intended the name of this species to have been derived from the Malay word when he described this species back in 1879 is a subject for further investigation.

With this re-discovery, credited to ButterflyCircle members Nelson and Yiming, the Singapore Butterfly checklist edges closer to the 300 mark as we record this as species #298.

Text by Khew SK : Photos by Sunny Chir, Chng CK, Khew SK, Nelson Ong & Anthony Wong

References :

The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, The Malayan Nature Society.

Life History of the White Banded Flat

Life History of the White Banded Flat (Celaenorrhinus asmara asmara)

Butterfly Biodata:
Genus: Celaenorrhinus Hübner, 1819
Species: asmara Butler, 1879
Sub-species: asmara Butler, 1879
Wingspan of Adult Butterfly: 40mm
Caterpillar Local Host Plant: Jasminum elongatum (Oleaceae, common names: Common Malayan Jasmine, 扭肚藤).

A male White Banded Flat.

Physical Description of Adult Butterfly:

On the upperside, the wings are brown. On the forewing, there are hyaline subapical spots in each of spaces 6,7 and 8. There is also an oblique discal band extending from cell-end to vein 2. On the hindwing, there are some obscure darker brown markings. Underneath, the wings are similarly marked as per above. The male has erectile hair tuft on the hind tibia which gives the legs a rather hairy appearance.

A female White Banded Flat.

Field Observations of Butterfly Behaviour:  
This species is rare in Singapore and its distribution is restricted to a few areas in the offshore island of Pulau Ubin. A small colony was rediscovered in 2011, and since then sightings have been very infrequent. As is the case for the Tagiades species, the adults have the habit of perching on the underside of a leaf between flights, and with its wings opened flat. The adults are also active only during the few hours after sunrise.

Early Stages:
To date only one local host plant, Jasminum elongatum, has been recorded for the White Banded Flat. This plant can be found growing at a few sites on Pulau Ubin, as well as being cultivated in multiple parks and gardens on the main island. Outside Singapore, Clerodendrum fragrans has also been recorded as the larval host. The caterpillars of the White Banded Flat feed on leaves of the host plant. When not feeding, the caterpillars seek  safety and concealment in a leaf shelter formed  by cutting and folding a leaf fragment along the edge of the leaf.

Local host plant: Jasminum elongatum.

The eggs of the White Banded Flat are laid singly on the underside of a leaf of the host plant. At times, several eggs can be found on different parts of the same leaf as a result of different oviposition visits by the same or different female. The whitish egg is hemispherical with surface marked with longitudinal ridges running from the pole to the rim of the base. Each egg has a basal diameter of about 1mm.

An egg of the White Banded Flat found on the underside of a leaf of the host plant.

Two views of an egg of the White Banded Flat.

The egg takes about 5 days to hatch. The young caterpillar emerges by eating away the polar  part of the egg shell. The rest of the egg shell is not eaten by the newly hatched which is about 2.2-2.3mm in length. The yellowish body is roughly cylindrical in shape and the head capsule is black or dark reddish brown in color. A prominent, black collar mark is present on the dorsum of the prothorax.

Left: mature egg. Right: empty egg shell.

Two views of a  newly hatched caterpillar of White Banded Flat cutting leaf lamina for its first leaf shelter, length: 2.3mm.

The newly hatched makes its way to the leaf edge to  construct its very first  leaf shelter right away. Typically the cut-out leaf fragment is turned over and secured to the upperside of the leaf. The caterpillar ventures out of the shelter from time to time to feed on the leaf lamina in the vicinity. As the caterpillar grows, the body assumes a green undertone. After reaching about 5mm in about 4-4.5 days, the caterpillar moults to the 2nd instar.

Top: a newly hatched caterpillar cutting the leaf lamina. Bottom: the completed leaf shelter with the cut-out folded over.

Two views of a 1st instar caterpillar of the White Banded Flat, length: 3mm.

Two views of late 1st instar caterpillar of the White Banded Flat, dormant prior to its moult to the next instar.

The body of the 2nd instar caterpillar is pale whitish to yellowish with a green undertone. There is no trace of the black collar mark on the prothorax seen in the 1st instar. The head is black and broadened sideways to two short tips at the upper end. The surface of the body is sparsely dotted with tiny whitish setae. This instar lasts about 5-5.5 days with the body length reaching about 8mm.

Two views of a 2nd instar caterpillar of the White Banded Flat, early in this stage, length: 4.5mm.

Two views of a 2nd instar caterpillar of the White Banded Flat, length: 6.5mm.

Two views of a late 2nd instar caterpillar of the White Banded Flat, dormant prior to its moult.

The 3rd instar caterpillar closely resembles the 2nd instar caterpillar. The head capsule is dark reddish brown but broader sideways and with the two raised tips more prominent. This instar takes about 5.5-6 days to complete with body length reaching about 12-13mm.

Two views of a 3rd instar caterpillar of the White Banded Flat, early in this stage, length: 7.5mm.

Two views of a 3rd instar caterpillar of the White Banded Flat, length: 9mm.

Two views of a late 3rd instar caterpillar of the White Banded Flat, dormant prior to its moult.

The 4th instar caterpillar is little changed from the 3rd instar in all body features. The head capsule is reddish brown soon after the moult, but turned dark reddish brown moments later. This penultimate instar lasts about 7.5-8.5 days with body length reaching about 20mm.

Two views of a 4th instar caterpillar of the White Banded Flat, early in this instar.

Two views of a 4th instar caterpillar of the White Banded Flat, length: 16mm.

Two views of a 4th instar caterpillar of the White Banded Flat, length: 19.5mm.

A leaf shelter of a 4th instar caterpillar of the White Banded Flat (top right leaf) sighted in the wild.

Two views of a late 4th instar caterpillar, dormant prior to its moult.

The 5th instar caterpillar has similar body markings as in the 4th instar initially. As in the 4th instar, the head capsule is bright reddish brown after the moult, but turning dark reddish brown moments later. As growth progresses in this instar, a thin yellowish lateral band appears on each side of the body. In this instar, and sometimes in the 4th instar, the leaf shelter is constructed from joining two adjacent leaves together. The 5th instar lasts for about 8-9 days, and the body length reaches up to 28-29mm.

Two views of a 5th instar caterpillar of the White Banded Flat, newly moulted with exuvia nearby.

Two views of a 5th instar female caterpillar of the White Banded Flat, late in this stage, length:28mm.

Two views of a 5th instar male caterpillar of the White Banded Flat, late in this stage, length:28mm. Note the pair of testes visible on the dorsum.

On the last day of 5th instar, the body decolorises  to a very pale whitish shade of yellowish green. The caterpillar ceases feeding and confines itself to the leaf shelter. The pre-pupatory larva prepares for the pupal phase with a series of silk construction work with the main pieces being a silk girdle across the dorsum of its early abdominal segments, and a short and thickened transverse silk band on the substrate at its posterior end. Soon the pre-pupatory larva becomes dormant in its leaf shelter. Pupation takes place about 1 day later.

A pre-pupa of the White Banded Flat seen through the side of the partially opened leaf shelter.

The girdled pupa is secured with its cremaster attached to the short transverse band on the substrate. It has a short thorax, a rather long abdomen, a pointed brown rostrum and two lateral brown cephalic processes. The body is pale whitish beige brown in the abdomen but yellowish green in the thorax and wing pads. There are two brownish patches on the upper part of the wing pad. The ventrum of the thorax has a remarkable convex downward outline. Length of pupae: 22mm.

Two views of a pupa of the White Banded Flat.

After about 6.5-7 days of pupal development, the pupal turns dark in the wing pad and thorax areas. The white discal band is also visible at this time. The following day, the adult butterfly emerges from the pupal case.

Two views of a mature pupa of the White Banded Flat.

A newly eclosed female White Banded Flat.

A newly eclosed female White Banded Flat, resting next to its pupal case.

A newly eclosed male White Banded Flat, resting atop its pupal case.

References:

• [C&P5] The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, G. and N.  van der Poorten (Eds.), 5th Edition, Malayan Nature Society, 2020.
• Butterflies of Thailand, Pisuth Ek-Amnuay, 2nd Edition, 2012.
• A Field Guide to the Butterflies of Singapore, Khew S.K., Ink On Paper Communications, 2nd Edition, 2015.

Acknowledgment:
I would like to express my gratitude to Timothy Liew, Loh Jian Kai and Zick Soh for sharing information on the host plant and early stages of the White Banded Flat.

Text by Horace Tan, Photos by Loh Mei Yee, Low Jian Kai, Sebastian Ow, Zick Soh, Anthony Wong, Khew SK and Horace Tan.