Butterfly of the Month - September 2010 The Lesser Harlequin (Laxita thuisto thuisto)
As we cross the threshold into the ninth month of 2010, most Asians are familiar with the Month of Ramadan where Muslims observe a full month of fasting. Hari Raya Aidil Fitri is now over, falling on Friday 10 Sep 2010. In Singapore's multi-racial society, where one colourful festival is celebrated and ends, another starts - the Mid-Autumn festival celebrated by the Chinese community. It's a festival where Chinese family members and friends will gather to admire the bright mid-autumn harvest moon, and eat moon cakes and pomelos under the moon together.
This month, we feature a butterfly from the family Riodinidae. The Riodinids are often referred to as "Metalmarks". Many species of this family feature attractively coloured metallic markings on their wings. The Riodinids are shade-loving butterflies, preferring to remain under the canopy of tall trees in forested areas. They have a habit of a hopping flight, stopping and then twisting and turning with half opened wings on the upper surfaces of leaves.
Our feature butterfly, the Lesser Harlequin, is a relatively small butterfly with a wingspan of about 35-45mm. This species behaves like the typical Riodinid, frequenting the heavily-shaded understorey habitats of Singapore's nature reserves and forested areas.
It flies around with a short hopping flight, and is quite skittish. At times, after a bit of flying around, the butterfly can stand still and 'sleep', staying motionless for long periods unless disturbed. But once alarmed, the Lesser Harlequin can take off to the treetops in a capable fashion. When seen in a particular location, the same butterfly can be observed to stay in the vicinity for a few days.
The Lesser Harlequin is reddish brown with blue-edged black spots on the underside of its wings. The iridescent metallic blue scales explain why the butterflies of this family are called Metalmarks.
The male Lesser Harlequin is all black on the upper surfaces of its wings. It has a stronger flight than the female but has only two pairs of legs that are developed for walking. The forelegs in the male are undeveloped and brush-like.
The female Lesser Harlequin has her upper wing surfaces marked like the underside. However, she has all three pairs of legs fully developed for walking. The eyes in both sexes are jet-black and featureless.
A female Lesser Harlequin ovipositing on a leaf of its host plant
The species is rare in Singapore, with infrequent observations of individuals in the forests after long intervals. A female was recently observed ovipositing and the host plant is known but not yet reliably identified.
Like its close relative, the Harlequin, little is known about its preferred habitat, its survival rate, or why it appears in certain areas and not others. Further studies and observations are needed to help conserve this species and to ensure its sustainability and existence amongst Singapore's butterfly fauna in the years to come.
Text by Khew SK : Photos by Sunny Chir, Federick Ho, Khew SK, Koh Cher Hern & Ellen Tan
A sunbathing male Long Banded Silverline displaying its striking upperside.
Physical Description of Adult Butterfly:
Above, both sexes are brown with an orange tornal patch on the hindwing. In addition, the male is purplish blue in the dorsal area of the forewing, as well as for almost the whole hindwing except the costal border. Underneath, both sexes are similar with a pale yellow ground colour. Both wings are traversed by 5 or 6 silverlines broadly edged with dark red or black. There are white-tipped, moderately long filamentous black tails at the end of veins 1b and 2, of which the pair at vein 1b longer is.The abdomen is striped in red to dark red.
A female Long Banded Silverline sunbathing between its ovipositing runs..
A Long Banded Silverline perching on a leaf.
Field Observations of Butterfly Behaviour:
This attractive species is uncommon in Singapore, despite the fact that it has a wide distribution across the main Singapore island. The fast flying adults have been sighted in multiple locations including Pulau Ubin, Sungei Buloh Wetland Reserve, Kranji Nature Trial, as well as iwastelands in the western and northern eastern part of Singapore. The adults seemed to have a fondness for flowers of the Mile-a-minute weed commonly found in wastelands.
A Long Banded Silverline taking nectar from flowers of the mile-a-minute.
Two close-up views of the silver lines on the wings.
Early Stages:
The immature stages of Long Banded Silverline are polyphagous and so far 6 plants have been recorded as local host. It is noteworthy to point out that one of them, Flagellaria indica, is a monocot and this is a very unusual host for a lycaenid butterfly. Caterpillars of all instars of the Long Banded Silverline feed on young to middle-aged leaves of the hosts, and have a strong association with ant species living on the same host plant.
Host plant: Sea Almond. Leaves and fruits are featured here. Host plant: Flagellaria indica.
In the field, a typical encounter of a Long Banded Silverline caterpillar would see it being attended by many ants. It is also likely that several caterpillars, sometimes of different instars, share the same leaf. Where available, the caterpillar also takes advantage of the ant pavilion, typically constructed by the attending ants on the leaf underside, and uses it as shelter from predator or parasitoids. Such strong association with ant species has earlier been observed and documented in earlier literature on this species. This strong ant association could be a reason why caterpillars of this species never made it to adulthood when they were taken from the field and bred in captivity. Breeding from the egg stage is however possible, and so far several ButterflyCirlce members have been able to do so successfully. The following account of the complete life history of Long Banded Silverline is based on specimens bred on Sea Almond.
A video clip showing the ant-caterpillar assocation between one Long Banded Silverline caterpillar and one ant species. Note the eversion of the tentacular organs when the ant got too close.
A mating pair of Long Banded Silverline on a grass blade. A female laying the second of a pair of eggs on the leaf upperside. The first egg can be seen near the abdomen tip.
Eggs are laid on the leaf surface or on a petiole. When laid on the green leaf surface, the female typically seeks out a small brown patch (where the leaf has been somehow damaged previously) to lay its eggs. The eggs are laid either singly or in pairs. Each egg is initially whtiish green, but turning light brown within minutes of being laid, and eventually chocolate-brown within hours. The coloration makes the eggs almost indiscernible against the brown substrate they were adhered to. Each egg is about 0.8mm in diameter, with a thick discoid shape. The egg is coarsely recticulated with rather large and deep pits and ridges. The micropylar sits atop at the center of the upper surface.
Two views of a pair of eggs laid on a damaged and brown patch on the upperside of a leaf.
Each egg takes about 6-7 days to hatch. The young caterpillar emerges after nibbling away sufficiently large upper portion of the egg shell. Measured at a length of about 1.8mm, its pale yellow green body is somewhat flatish with four rows of moderately long fine setae running lengthwise. Each body segment has a short protrusion laterally on both sides of the body. A very long black setae and a few shorter whitish setae emanate from each protrusion. The thorax except for the dorsal area of the 3rd thoracic segment is dark red, and there is a dark and rather large prothoracic shield. The posterior segments from the 8th abdominal segment are also dark red with a large black anal plate. Two small lateral processes are discernible on the 8th abdominal segment. The head capsule is black.
Left: a pair of mature eggs. Right: one new hatched caterpillar with another still eating its way out.. Two views of a 1st instar caterpillar, early in this stage, length: 2mm.
As the caterpillar grows, its body broadens sideway.The growth is slow and after about 3-3.5 days, it only reaches about 3-3.5mm in length when it stops for the moult to the 2nd instar.
Two views of a 1st instar caterpillar, late in this stage, length: 2.8mm.
Covered with numerous short setae (each with an enlarged tip), the body of the 2nd instar caterpillar is pale yellow in base color and is flattened dorso-ventrally. The prothoracic shield is dark and much larger than in the 1st instar. There are two dorso-lateral series of small red markings on the first 6 abdominal segments.Each of the three thoracic segments and the first 7 abdominal segments bears a pair of lateral cone-shaped projections furnished with a tuft of short to moderately long whitish setae. Each of these setae is not smooth but carry a number of spikes along its length. The dorsal nectary organ is now discernible on the 7th abdominal segment. On the 8th abdominal segment, there are two prominent cone-shaped projections housing the tentacular organs. The last 2 posterior segments are fused into an enlarged flat structure carrying the black anal plate on its dorsum.
Two views of a 2nd instar caterpillar, early in this srage, length: 3.3mm.
The growth in this stage brings the caterpillar to a length of about 4.5-5mm, and after about 3-3.5 days in this stage, it moults again.
Two views of a 3rd instar caterpillar, late in this stage, length: 4mm.
The 3rd instar resembles the 2nd instar caterpillar in most aspects. Now the eversion of the tentacular organs can be readily observed. A large dorsal band, bordered by the two dorso-lateral series of dashed markings, is vaguely defined. Each of these dorso-lateral markings consists of a dark red patch flanked upwardly by a whitish patch. This instar takes 3-4 days to complete with the body length reaching about 7-8mm before the next moult.
Two views of a 3rd instar caterpillar, newly moulted, length: 4mm. Two views of a 3rd instar caterpillar, late in this stage, length: 6mm.
The 4th instar caterpillar has a distinct dorsal band highlighted by a much darker shade of yellowish green along its doro-lateral border, in contrast to the much lighter shade in the body ground colour. A thin pale dorsal line sits in the middle of the dorsal band. The another visual difference is in the greater orange tone in the first 2 thoracic segments. This instar lasts about 3.5-4 days with length reaching 10mm.
Two views of 4th instar caterpillar, early in this stage, length: 6.5mm. Two views of 4th instar caterpillar, late in this stage, length: 9mm. Several caterpillars of the Long Banded Silverline taking shelter in an ant pavilion on the underside of a Sea Hibiscus leaf.
The 5th instar caterpillar has a much more prominent dorsal band due to the assumption of a much darker tone of yellow and orange in its coloration. The greater orange tone is also found in the thoracic and posterior segments. The body base colour is yellowish green in one form, and brownish in another. This instar lasts about 3.5-4.0 days with length reaching 14mm.
A 5th instar caterpillar, newly moulted, length; 8.5mm.
A 5th instar caterpillar, early in this stage, length: 9mm. Two views of a 5th instar caterpillar, late in this stage, length: 12mm.
Compared to the earlier instars, the 6th (and final) instar caterpillar has a much darker coloration especially in the dorso-lateral series of markings. The thin dorsal line is also highlighed by flanking black lines. This instar lasts about 6-7 days with the length reaching up to 24mm.
The two late instar caterpillars in a shallow leaf shelter. The left one is about to moult to the 6th instar, and the right one is in early 6th instar. Two views of a 6th instar caterpillar, early stage, length: 12.5mm. Two vliews of 6th instar caterpillar, later in stage, length: 18mm. Two final instar caterpillars found on the underside of a Sea Almond Leaf in the field. One was partially hidden in an ant pavilion while another was feeding nearby.
Towards the end of the 6th instar, the caterpillar ceases eating and its body shortens in length as it seeks out a pupation site. In the field, one common pupation site is an available ant pavilion. Otherwise the caterpillar creates a shallow pupation shelter on a spot of the leaf surface with a number of silk threads. Within the pupation shelter, the pre-pupatory caterpillar readies itself for pupation by spinning a silk pad to the substrate. No silk girdle is used as the pre-pupa secures itself to the silk pad via the claspers at its posterior end.
Two views of a pre-pupatory larva of the Long Banded SIlverline.
Pupation takes place after 1.5-2 days of the pre-pupal stage. The pupa has the typical lycaenid shape, yellowish green in the abdomen and green in the thorax and wing pads. The pupa has a length of about 10-12mm.
Two views of a pupa of the Long Banded Silverline. A pupa of the Long Banded Silverline found in the field. Pupa was seated within an ant pavilion. The bottom picture shows the pupa exposed after the top of the ant pavilion was removed.
Eight days later, the pupa becomes darkened in color signaling the imminent emergence of the adult. The next day the adult butterfly emerges from the mature pupa. (Note: Based on breeding experience of ButterflyCircle members of this species, having six instars for the larval stage seems to be norm but there were exceptions where the number of instars reached up to 8.)
Two views of a mature pupa of the Long Banded Silverline. A newly eclosed Long Banded Silverline "drying" its wings.
References:
The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, Malayan Nature Society.
Life Histories of Asian Butterflies, Vol. II, Igarashi S. and Fukuda H., Tokai University Press, 2000.
Text by Horace Tan, Photos by James Chia, C K Chng, Ben Jin Tan, Sunny Chir, Khew SK and Horace Tan
A shot of the Coon taken at Endau Rompin Forest Reserve in Malaysia
The family Hesperiidae (or commonly known as Skippers) feature rather unattractive butterflies. They are fast flying, with big eyes and many of them perch with their wings opened in a unique fashion, known only to the Hesperiidae - with their forewings held out at a 45 deg angle, whilst the hindwings are opened flat.
A shot of the Forest Hopper taken in Singapore
Many skippers are brown, unmarked and not typical of what enthusiasts, hobbyists and nature photographers would find particularly beautiful in a butterfly. Hence it is not surprising that many of these ubiquitous butterflies go about their daily lives, flitting amongst flowers in the early morning hours and later hours of the day largely unnoticed.
A Forest Hopper perches on a blade of grass
Of particular interest would be the many lookalikes which are difficult to identify with a high level of confidence from just field shots. To add to this difficulty, the large variations in the physical characteristics like their hyaline spots, markings and colours in both the males and females make it extremely challenging to distinguish between certain species without examining them scientifically - i.e. dead in a collection or via dissection of the genitalia.
Another Forest Hopper on a leaf
Early in the compilation of the Butterflies of Singapore checklist, I had inadvertently classified a predominantly brown and unattractive skipper as the Coon (Psolos fuligo fuligo). For a long time, we had assumed that this was the species flying around the grasslands in Singapore.
Recently, one of ButterflyCircle members, Dr S. Kalesh, who hails from Trivandrum (or Thiruvananthapuram) in India, and who is a specialist in Hesperiidae, corrected this mistake. The Singapore Checklist has been updated accordingly, as after examining the repository of photographs and also voucher specimens amongst ButterflyCircle members and my own collection, the Coon (Psolos fuligo fuligo) is unfortunately no longer extant in the Singapore environment. Although it is listed in the Checklists of Butterflies of the Malay Peninsula (C&P4), there has be no reliable evidence that this species still exists in Singapore and therefore removed from the Checklist until such time any evidence of its presence can be validated.
A shot of the Coon taken in India
The butterfly that had earlier been mis-identified as the Coon, has now been confirmed to be the Forest Hopper (Astictopterus jama jama) and reinstated to the Singapore Checklist. This predominantly brown skipper is described as "above and below the butterfly is dark brown and is usually unmarked although there may be two or three white hyaline subapical dots on the forewing.
A Forest Hopper feeds on a yellow flower
In C&P4, page 351, the authors continued to mention that "The unicolourous underside and porrect palpi differentiate this species from the superficially similar Psolos fuligo (Coon)". The Coon, on the other hand, is described to have a few small and rather obscure ferruginous spots on the forewing and hindwing.
Dr S Kalesh further added that,
Note the 'hunchbacked' appearance of the Coon and also the obscure spots
In the Coon : The forewing tips diverge from each other and the wings are more produced in coon. Underside hue is brown with a violetish tinge with some pale brown areas. The forewings also curve in a convex manner, giving the butterfly a "hunchbacked" look.
The unicolourous underside of the Forest Hopper and the three subapical hyaline spots on the forewing
In the Forest Hopper : The underside is blackish brown with grey scales occationally also with 3 apical spots and the wingtips dont diverge from each other.
Another Forest Hopper perched on a blade of grass
The shots in this blog article show the differences between the Coon and the Forest Hopper. The other species that are extant in Singapore and that may be confused with these two species would be the Chocolate Demon (Ancistroides nigrita maura) and the all-brown male of the rare skipper Quedara monteithii monteithii.
Text by Khew SK ; Photos by Federick Ho, Dr S Kalesh, Khew SK, Horace Tan & Wong CM
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