Plus Two makes 284

Re-discovery of two more species of Lycaenidae brings the Singapore Checklist to 284 species.

The recent re-discovery of two more species of Lycaenidae - one from the genus Nacaduba and the other from the genus Manto brings the total number of species in the Singapore Checklist to 284 species.

The Jewel Four-Line Blue (Nacaduba sanaya elioti)

The first species is the Jewel Four-Line Blue (Nacaduba sanaya elioti ). The genus Nacaduba comprise many species which look very similar to each other and are not easy to identify in the field. However, our ButterflyCircle member, Horace Tan, who specialises in the early stages of butterflies, managed to observe this species over a few months and managed to breed the species from egg to adulthood.

The pristine adult specimens were then compared with the reference books and it was discovered that this specimen was not similar to the other species already recorded in the Singapore checklist. This species, obviously belonging to the pavana group (the 4-line Blues) is also without a basal pair of lines in the forewing cell beneath.

A female Jewel Four-Line Blue oviposting on its host plant, and the leaves of the host plant of this species.

After careful investigations and seeking advice from our foreign expert, Prof Konrad Fiedler, a renowned expert in tropical Lycaenidae, it was confirmed that this species is indeed the Jewel Four-Line Blue (Nacaduba sanaya elioti). It is now re-instated into the Singapore Checklist, where it was originally recorded as extant by Corbet & Pendlebury as well as W. A. Fleming.

The Green Imperial (Manto hypoleuca terana)

The second species is the Green Imperial (Manto hypoleuca terana). Described as "rather rare and is more often taken in the forest at low to moderate elevations than on the hill tops", the species has been earlier observed, but only on this opportune occasion where a pristine male was observed with its characteristic green upperside, when the species could finally be positively identified.

This species appears superficially similar to the Grand Imperial (Neocheritra amrita amrita) and the Great Imperial (Jacoona anasuja anasuja). However, the Green Imperial has a wider suffusion of orange on the hindwing below, almost reaching the dorsal margin of the hindwing below, unlike the other two species, particularly in the males. That the post-discal striae reach vein 6 on the hindwings also reaffirms this species identification.

Photographed at the edge of the nature reserves feeding on the flowers of the Yellow Cane Palm (Dypsis lutescens), the fortunate encounter has confirmed the existence of this rare Lycaenid in Singapore, and the species Green Imperial (Manto hypoleuca terana) has been reinstated to the Singapore Butterfly checklist as species # 284.

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

Life History of the Malayan Bush Brown

Life History of the Malayan Bush Brown (Mycalesis fusca fusca)

Butterfly Biodata:
Genus: Mycalesis Hübner, 1818
Species: fusca C. & R. Felder, 1860
Subspecies: fusca H C. & R. Felder, 1860
Wingspan of Adult Butterfly: 45mm
Caterpillar Local Host Plant: Scleria bancana (Cyperaceae)

Physical Description of Adult Butterfly:
Underside, both wings are yellowish brown in ground colour, with two reddish/orangy brown longitudinal stripes crossing from the upper to lower edges, and a series of moderate to small ringed spots (ocelli) in the submarginal area. The post-discal area of the hindwing carries a reddish brown coloration. Above, the male is brown with obscure post-discal ocelli while the female is pale brown with more distinct post-discal ocelli. The female is typically larger in size.

Field Observations of Butterfly Behaviour:
This species is one of the less common of the Mycalesis genus in Singapore, and thanks to its more striking undersides, it is also one of the more distinctive members of this genus which typically features dull brown adults. Local sighting locations include the Central Catchment Nature Reserve and the Bukit Timah Nature Reserve. Individuals are usually encountered flying alongside forest trails or lurking in shady undergrowth in the vicinity of its host plant. As with other Satyrinae members, the adults fly in an erratic and jerky manner as their wings are closed for a relatively long period during flights.

Early Stages:
The host plant is a member of the Cyperaceae (Sedge) family, a grass-like herb with triangular stems and 3-ranked leaves with sheaths. This plant is rather common in the Catchment Reserves and even along trails in the Southern Ridges.

Host plant: Scleria bancana.

The eggs of the Malayan Bush Brown are laid singly on the grass leaf blade. Each egg is more or less spherical (about 1mm in diameter) and light translucent yellow. It appears to be smooth to the naked eyes, but faintly sculptured with a hexagonal reticulum when viewed with a more extreme close-up camera set-up.

A fresh egg of Malayan Bush Brown

The egg takes 4 days to mature. The young caterpillar pushes its way through the cracked egg shell, and then proceeds to eat up the egg shell almost entirely. It has a spindle-shaped body in light creamy yellow colour, and an initial body length of about 4mm. The body has rugose and ill defined segments. There is a pair of backward-pointing anal projections and a black head with a pair of short and rounded horns on the head. The young caterpillar eats the leaf blade along the edge. Caterpillars of all instars are observed to be sluggish in movement. They tend to rest lengthwise on the underside of a leaf during pauses between feeds.

Mature egg with the head about to break through the shell

Newly hatched 1st instar caterpillar, length: 4mm

The first instar lasts 4 days with the body length increases to about 6mm before the inevitable moult. With the change of instar, the two cephalic on the head become pointed and the two anal projections longer and thus pronounced. The body colour is yellow with a green undertone. The head and body is also roughened by numerous minute tubercles, each with a single seta. Faint longitudinal lines are also distinguishable on the body.

2nd instar caterpillar, early in this stage, 6.5mm

2nd instar caterpillar, late in this stage, length: 10mm

The 2nd instar lasts for 4 days with the body length reaches about 11mm before the next moult. The 3rd instar caterpillar mostly resembles the previous instar except for having longer anal projections and more prominent longitudinal lines on its body. This stage also takes 4 days to complete with body length reaching about 16mm.

3rd instar caterpillar, early in this stage, length: 11mm

3rd instar caterpillar, late in this stage, length: 13mm

One obvious change in the 4th instar caterpillar is in the head where the "face" area has changed from dark brown to yellowish green while the forward-facing portions of the horns remaining dark brown. The 4th instar lasts about 5 days with body length reaching 22-23mm.

4th instar caterpillar, length: 16mm

The next moult brings the caterpillar to its 5th and final instar. Now the "face" area of the head is pale yellow in colour and decorated with three pairs of curved brown lines. The body is dotted with several prominent black spots, and the longitudinal lines become more striking with alternating and varying shades of brown and green. In a period of 9 days, the body grows at a faster pace to a maximum length of about 40-42mm.

5th instar caterpillar, early in the stage, 30mm

5th instar caterpillar, late in this stage, length: 40mm

Toward the end of 5th instar, the body gradually shrinks in length and becomes paler in colouration. Finally the caterpillar finds a spot on the underside of a leaf blade to secure itself at the anal end. The dormant pre-pupatory pose is complete once it has its body curved up and the head touches part of the body.

Preparatory pupa of Malayan Bush Brown

After one day as a pre-pupa, pupation takes place. The smooth pupa is light woody brown with faint brown markings. It is somewhat angular, with a dorsal keel on the thorax and ridges defining the dorsal wing margins. Length of pupae: 15-16mm.

Fresh pupa of Malayan Bush Brown

After 9 days of development, the pupa becomes darkened in color especially at the wing pads (corresponding to the dark brown uppersides of the forewings). The next day the eclosion event takes place with the adult butterfly emerges to start the next life cycle.

Mature pupa of Malayan Bush Brown

A newly eclosed Malayan Bush Brown

References:

• The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, Malayan Nature Society.
• The Butterflies of Hong Kong, M. Bascombe, G. Johnston, F. Bascombe, Princeton University Press 1999

Text and Photos by Horace Tan

Butterfly of the Month - May 2008

BUTTERFLY OF THE MONTH - MAY 2008
The Plain Nawab (Polyura hebe plautus)

The Plain Nawab (Polyura hebe plautus) belongs to the sub-family Charaxinae, which feature large, heavy-bodied robust butterflies which are capable of rapid and swift flight. There are seven known species of this genus in Malaysia, of which two are found in Singapore. Both species, the Plain Nawab (Polyura hebe plautus) and the Blue Nawab (Polyura schreiber tisamenus) are not considered very rare.

The Plain Nawab is the commoner of the two known species of the genus in Singapore. The butterfly is greenish white above and the forewing has a broad black apical border, which is very wide at the apex, but decreases in width towards the tornus and base of the costa. There is a greenish white subapical spot on the forewings and a series of submarginal spots on the hindwings.

The underside has a large, pale silvery green median patch, which covers a little more than a quarter of the wing. It is represented by the subspecies plautus in Singapore, and which can be distinguished by a broad black bordered hindwing. The Malaysian subspecies that is usually encountered, chersonesus, has a narrow hindwing border.

As in most of the typical Polyura species, the hindwings of the Plain Nawab feature a pair of short stubby tails each – slightly broader and longer in the female and narrower and sharper in the male.The butterfly has a strong and erratic flight. It has a habit of perching on a lofty leaf or branch, surveying the grounds below. It then flies rapidly in the vicinity of its perch, often 'attacking' intruders and chasing other flying objects away, but coming back again and again to the same preferred perch to rest. This species can also be observed puddling on roadside seepages, carrion, faeces and tree sap.

A Plain Nawab puddling at a sandy seepage.


A Plain Nawab feeding on tree sap

The caterpillar of the Plain Nawab feeds on the Leguminosae Adenanthera pavonina (commonly known as the Red Saga). Females of this species have also been observed ovipositing on the young Petai (Parkia speciosa) plant, and Albizzia (Falcataria moluccana) both of which appear to be an alternative host plants.

Its habit of weaving a silken pad on one of the leaves as its “base camp”, from which it makes it nocturnal forays to other parts of the Saga plant to eat, is a behaviour unique to both the Polyura species in Singapore. As the caterpillar grows larger, it takes on a two-shade green appearance, with triangular wedge-shaped stripes along the length of its body. It is interesting that it still maintains its silken pad base-camp, although the pad now consists of many leaves weaved together to accommodate the large caterpillar. It makes no attempt to conceal itself, and stays stationary on its silken pad in the daytime, feeding mostly at night.

Final instar caterpillar of the Plain Nawab resting on its "base camp". The host plant is Falcataria moluccana  in this case.

Another puddling Plain Nawab

Mating pair of the Plain Nawab

Text by Khew SK : Photos by Horace Tan, James Chia and Khew SK

Life History of White Spot Palmer

Life History of the White Spot Palmer (Eetion elia)

Butterfly Biodata:
Genus: Eetion de Nicéville, 189
Species: elia Hewitson, 1866
Wingspan of Adult Butterfly: 38mm
Caterpillar Local Host Plant: Sarcotheca griffithii (Oxalidaceae)

Physical Description of Adult Butterfly:
Above , the wings are dark brown with the forewing possessing separated white hyaline spots in the cell and in spaces 1b, 2, 3, 4 and 5 (two minute spots), and with sub-apical spots in spaces 6 to 8. On the hindwing upperside, there are spots in spaces 1b, 2, 3 and conjoined spots in spaces 4 and 5. The hindwing underside has the basal half silvery white below vein 8. The abdomen is dark brown, white banded above and entirely white beneath. On the upperside of the forewing, the male has a narrow arcuate whitish brand from just below vein 2 to before the origin of vein 3.

A view of the upperside of a male Eetia elia showing its brand.

Field Observations of Butterfly Behaviour:
This species is rarely encountered in Singapore. Past sighting locations of the adults include various parts of the Central Catchment Area such as MacRitchie Nature Trail, Sime Forest and Upper Seletar Reservoir Park. As typical with other skippers, the adults fly with swift and darting flights.

Early Stages:
Thus far, only one local host plant has been identified. The plant is Sarcotheca griffithii, a rare plant species mainly found in the central catchment reserve.

Host plant:Sarcotheca griffithii.

Close-up view of leaves of Sarcotheca griffithii.

The eggs are laid singly on the leaf upperside of the host plant. Each egg is mostly pink and has a darker shade of pink at the micropylar area. It is spherical with a flattened base and has a surface covered with a fine mesh of short wavy lines. The diameter is about 0.9mm.

Two views of an egg of Eetia elia

Mature egg with a faint view of the head (left), empty egg shell (right).

It takes 3 days for the collected egg to hatch. The young caterpillar eats just enough of the shell to emerge, and has a length of about 2.5mm. It has the typical cylindrical shape for skipper caterpillars, and a large black head. The body colour of the 1st instar could range from yellow to orange as depicted below.

1st instar caterpillar, length: 2.5mm.

After a quick exit and look around, the young caterpillar returns to the remnant of the egg shell to munch away more of the egg shell for its first meal. It does not finish the entire egg shell and soon makes its way to the leaf edge to construct its first leaf shelter. It rests within the shelter and ventures out to eat the leaf surface nearby and parts of the shelter. With additional cuts to the leaf flap and further silk threading work, the shelters for the first instar (and second instar) caterpillars soon assume a convex and tent-like appearance.

1st instar caterpillar, 4mm.

The tent-like leaf shelter for a late 1st instar caterpillar.

As with some other skipper species, Eetion elia caterpillars have been observed to ballistically eject their faecal pellets (frass) at speed, ensuring that the pellets are displaced as far away as possible from the shelter. This is believed to be a self-defense strategy, preventing potential predators or parasitoids from following the chemical signature of the frass to the originator.

2nd instar caterpillar, early in this stage, length: 7mm.

After 3 days in 1st instar and reaching a length of about 5mm, the caterpillar moults to the next instar within the shelter. The 2nd instar caterpillar is yellow with a green undertone. It reaches a length of about 9mm after 3 days of growth in this instar. The 3rd instar caterpillar has similar appearance as in the previous instar. As it grows, the body takes on bands of transverse ring patterns alternated with bands of smooth skin. The 3rd instar lasts about 5 days with the body length reaches 14-15mm. The leaf shelters for the larger caterpillars in 3rd and later instars are made from bringing two edges of the leaf together with sinuous cuts and silk threads, resulting in a ``curry puff'' appearance. The caterpillars eat the leaf adjacent to the shelter as well as the edges of the shelter.

3rd instar caterpillar, early in this stage, length: 9mm.

3rd instar caterpillar, late in this stage, length: 15mm.

Leaf shelter for a 3rd instar caterpillar over a 2-day period.

The 4th instar caterpillar has a rather different looking head capsule. There are three large and dark brown spots set among a light brown base colour. This instar takes about 5 days to complete with the body length reaching 23-24mm.

4th instar caterpillar.

5th instar caterpillar, early in this stage, 26mm.

The head capsule of the final and 5th instar caterpillar has an orange base color, and has all three black spots well defined and set within rings of beige coloration. This stage takes about 9-10 days to complete with the body length reaching 40mm.

5th instar caterpillar, late in this stage, length: 40mm.

At the end of 5th instar, the body of the caterpillar shrinks in length. Soon it becomes dormant in its leaf shelter and enters the prepupatory phase which lasts for one day.

Pre-pupatory larva of the White Spot Palmer.

Pupation takes place within the leaf shelter. The pupa secures itself with its cremaster attached to a short transverse band on the leaf surface, and has a silk girdle. The pupa is mostly pale green in base colour. It has a short thorax, a rather long abdomen, a long and pointed rostrum. There is also a pair of small but distinct orange-brown patches on the anterior part of the mesothorax. Length of pupae: 30-34mm.

Fresh pupa of the White Spot Palmer.

After 9 days, the pupa becomes mostly black in color with spots on the forewing upperside visible through the now transparent skin. Eclosion takes place the next day.

Mature pupa of the White Spot Palmer.

A newly eclosed White Spot Palmer.

Another newly eclosed White Spot Palmer.

References:

• The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, Malayan Nature Society.
• The Butterflies of Hong Kong, M. Bascombe, G. Johnston, F. Bascombe, Princeton University Pres 1999

Text and Photos by Horace Tan