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.

References:

• 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.

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.

Life History of the Dingy Bush Brown

Life History of the Dingy Bush Brown (Mycalesis perseus cepheus)

Butterfly Biodata:
Genus: Mycalesis Hübner, 1818
Species: perseus Fabricius, 1775
Subspecies: cepheus Butler, 1867
Wingspan of Adult Butterfly: 35-45mm
Caterpillar Local Host Plants: Ischaemum ciliare (Poaceae, common names: Smut Grass), Axonopus compressus (Poaceae, common names: Wide-leaved Carpet Grass, Cow Grass).

Physical Description of Adult Butterfly:
On the upperside, the wings are dark greyish  brown with a large but obscure ocellus in space 2 of the forewing. The male has a small, dark brown sex brand in space 1b of the forewing, and another one at vein 7 of the hindwing overlaid with a pale yellow hair tuff. On the underside, both wings are pale brown in ground colour (with the male in darker brown than the female) and have a clear-whitish post-discal band. There is a series of ringed ocelli in the submarginal area on both wings. In the forewing, the submarginal ocelli usually include only one ocellus in each of spaces 2 and 5, and two smaller ocelli in between.  In the hindwing, there is a thin, dark indentation line  stretching down to (but not beyond) vein 1b. Furthermore, the submarginal series of ocelli has an arched appearance with the ocellus in space 2 moved inwards and out of alignment with those in spaces 1b and 3.

A pair of Dingy Bush Brown. Left: male; Right: female.

Field Observations of Butterfly Behaviour:
The Dingy Bush Brown is a moderately common butterfly in Singapore. Adults can be sighted flying low, in and around grassy patches at several locations across the island. 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:
Two grass species, Ischaemum ciliare and Axonopus compressus, have been recorded as larval hosts for the Dingy Bush Brown in Singapore so far. The caterpillars feed on leaves of the host plant, and have been observed to forcefully ejecting their frass pellets, a larval habit rarely seen outside the skipper/flat families. They tend to rest lengthwise on the underside of a leaf during pauses between feeds.

Forceful ejection of frass pellets by caterpillars (in all five instars) of the Dingy Bush Brown.

Local host plant #1: Ischaemum ciliare.

Local host plant #2: Axonopus compressus.

A mating pair of the Dingy Bush Brown.Left: male; Right: female.

The eggs are laid singly on the underside of a grass blade. Each oblate ellipsoidal egg (about 1.1mm in diameter and 1mm in height) is pale translucent green. The surface appears smooth to the naked eyes, but is actually sculptured with a polygonal reticulum when viewed with a macro lens.

Two views of an egg of the Dingy Bush Brown .

The egg takes about 3 days to hatch. The young caterpillar nibbles away a portion of the egg shell to exit and then proceeds to devour the rest of the egg shell almost entirely. It has a cylindrical body in whitish colour, and an initial body length of about 3.2mm. The body is covered with dorso-lateral and lateral rows of whitish setae. At the posterior end, there is a pair of backward-pointing processes. Its dark colored head features a number of setae and has a pair of short and rounded horns and a few lateral protuberances.

Two views of a newly hatched caterpillar, length: 3.25mm.

As a result of its leaf diet, the 1st instar caterpillar soon takes on a greenish undertone and its body lengthens gradually. The first instar lasts about 2.5-3 days with the body length increases to about 6-6.5mm.

Two views of a 1st instar caterpillar, length: 6mm.

Two views of a late 1st instar caterpillar, dormant prior to its moult, length: 6.25mm.

In the 2nd instar, the cephalic horns become pointed and the two anal processes longer and thus pronounced. The few lateral conical protuberances on the head capsule are now much smaller and whitish in colour. The body is yellowish green. The head and body is also adorned with numerous minute tubercles, each with a single seta emanating from it. The 2nd instar lasts about 2.5-3 days with the body length reaches about 10-10.5mm.

Two views of a 2nd instar caterpillar, early in this stage, length: 6.8mm.

Two views of a 2nd instar caterpillar, length: 8.5mm.

Two views of a late 2nd instar caterpillar, dormant prior to its moult, length: 10mm.

The 3rd instar caterpillar mostly resembles the previous instar. The head capsule is reddishbrown in the cephalic horns and the basal areas around the mouth parts but yellowish brown elsewhere. This stage also takes 2.5-3 days to complete with body length reaching about 14.5-15mm.

Two views of 3nd instar caterpillar, early in this stage, length: 10.2mm.

Two views of a 3nd instar caterpillar, length: 15mm.

Two views of a late 3nd instar caterpillar, dormant prior to its moult, length: 14.5mm.

The 4th instar caterpillar bears a close resemblance to the 3rd instar caterpillar with no obvious change of any features or markings. The 4th instar lasts about 4 days with body length reaching about 20-22mm.

Two views of a newly moulted 4th instar caterpillar, length: 14mm.

Two views of a 4th instar caterpillar, late in this stage, length: 20mm.

Two views of a late 4th instar caterpillar, dormant prior to its moult, length: 22mm.

The next moult brings the caterpillar to its 5th and final instar. Now the caterpillar could appear in two colour forms: a brown form which is mostly pale brown and a green form which is pale yellowish green. In a period of about 6 days, the body grows to a maximum length of about 40-41mm.

Two views of a newly moulted 5th instar caterpillar, green form, length: 19mm.

Two views of a 5th instar caterpillar, green form, length: 32mm.

Toward the end of the 5th instar, the body gradually shrinks in length. Typically, the caterpillar will seek out a spot on the underside of a leaf blade to spin a silk pad. It then anchors itself there via its anal end, and assumes its upside-down pre-pupatory pose.

Two views of a 5th instar caterpillar, brown form, late in this stage, length: 33.5mm.

A prep-pupa of the Dingy Bush Brown.

After one day as a pre-pupa, pupation takes place. The smooth pupa is mostly green throughout with its surface dotted with numerous tiny whitish spots. It is somewhat angular in appearance, with a small dorsal keel on the thorax and ridges defining the dorsal wing margins. There are a few small black spots dotting the wing pad margin. Dorso-lateral pairs of round and whitish spots can be observed on some abdominal segments. Length of pupae: 14-15mm.

Three views of a pupa of the Dingy Bush Brown.

After about 5 days of development, the pupa becomes darkened in color, and the ringed-spot on the forewings can now be seen through the pupal skin in the wing pads. The next day the eclosion event takes place with the adult butterfly emerges to start the next phase of its life cycle.

Three views of a mature pupa of the Dingy Bush Brown.

A newly eclosed female Dingy Bush Brown.

References:

• [C&P4] The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, Malayan Nature Society.
• Butterflies of Thailand, Pisuth Ek-Amnuay, 2nd Edition, 2012.
• A Field Guide to the Butterflies of Singapore, Khew S.K., Ink On Paper Communications, 2010.

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