28 January 2018

Favourite Nectaring Plants #15

Butterflies' Favourite Nectaring Plants #15
The Spicate Eugenia (Syzygium zeylanicum)

A Plane (Bindahara phocides phocides) feeding on the flower of Syzygium zeylanicum

This article features a relatively widespread species of the Syzygium genus, the Spicate Eugenia (Syzygium zeylanicum). The genus Syzygium comprise flowering plants that belongs to the myrtle family, Myrtaceae. The genus comprises about 1200–1800 species, and has a native range that extends from Africa and Madagascar through southern Asia east through the Pacific. Its highest levels of diversity occur from Malaysia to northeastern Australia, where many species are very poorly known and many more have not been described taxonomically.

A Spicate Eugenia tree in full bloom along the fringe of the nature reserves

Several species of Syzygium are well-known as a popular local fruit called "Jambu", a pink or red crunchy and thirst-quenching fruit that is often eaten "off the tree". The flowers of the Syzygium spp are quite unique in that they often bloom in bushy white clusters, giving the tree a "wintry" appearance. When in full bloom, many species of the Syzygiums attract insects and other pollinators to feed on the nectar of its flowers.

Buds and flowers of the Spicate Eugenia

Whilst we feature the Spicate Eugenia as our 15th butterflies' favourite nectaring plant, there are several other local Syzygium species, like S. glaucum, S. myrtifolium, S. lineatum and probably several other species that look quite similar to the Spicate Eugenia and whose flowers are equally as attractive to butterflies. These plants can be found in Singapore's parks and nature reserves and whenever they are in bloom, it is always a delight to enjoy the numerous species of butterflies feeding on the flowers of these plants.

The genus name Syzygium is derived from 'syzygos' (Greek for 'joined'), alluding to the opposite paired leaves. The species name 'zeylanicum' refers to Ceylon (old name for Sri Lanka), where the species is also naturally distributed. The Spicate Eugenia is native to Singapore and has a distribution range across East Madagascar, through India, South China to Southeast Asia.

Plant Biodata:
Family: Myrtaceae
Genus: Syzygium
Species: zeylanicum
Synonyms: Eugenia longicauda, Eugenia zeylanica, Eugenia varians, Myrtus zeylanica, Syzygium spicatum, Eugenia spicata
Country/Region of Origin: Native to Singapore
English Common Names: Spicate Eugenia
Other Local Names: Kelat Nasi Nasi, Kelat Nenasi, Gelam Tikus, Gelam Paya, Gelam Tikus Laut, Kelat Merah, 锡兰蒲桃

A Spicate Eugenia tree in full bloom.  Can you spot the two butterflies feeding on the flowers?

The Spicate Eugenia is a small to medium-sized tree that can grow up to 18 m tall, attain 100 cm in girth size, with oval to rounded crown.. The bark of the tree is reddish-brown and papery-flaky in young specimens. Where cultivated in parks or the fringes of nature reserves, it is planted single in rows or close together to form a hedge or a visual screen. It is sometimes seen growing wild on our natural coastal cliffs such as those on St John's Island and Labrador Park. In other areas, it is cultivated at Singapore Botanic Gardens, Upper Seletar Reservoir Park, Pulau Ubin, Pulau Tekong, Telok Blangah Hill Park and many other parks in Singapore.

Leaves of the Spicate Eugenia. Young leaves are orangish-pink and glossy

The leaves are opposite, short-stalked and leathery, elliptical to lance-shaped, 5–11 cm long by 2–5 cm wide with a pointed leaf tip. Each leaf has one vein running parallel to the leaf margin, and 10–14 pairs of side veins. Mature leaves dark glossy green above, paler green below, with numerous secondary veins spaced 2-3 mm apart and at 80°-85° angle from midvein, veins conspicuous on upper leaf surface and slightly raised on bottom surface. The young leaves are purplish to orangish-pink and very glossy.

Close up of the flowers of the Spicate Eugenia

The flowers of the Spicate Eugenia are bisexual and are white, faintly fragrant, and found in up to 2.5–4 cm long flower clusters located at ends of its branches, or axils of its leaves. The flowers are bushy, often described to look like "pom-poms" and are highly attractive to butterflies and other insect pollinators. When in full bloom, the tree looks like it is covered in white "snow". The flowers are delicate, and usually do not last for more than a week.

The whitish-green fruits of the Spicate Eugenia with a Copper Flash standing guard

The plant produces fleshy fruits that are oblong-round, 0.5–0.7 cm in diameter, white and each fruit contains one greenish seed. The small berries ripen from greenish to white and freckled with several brownish spots. The relatively thin pulp is soft and fleshy, and is edible. The seeds are eaten by birds, squirrels and other fruit-eating animals.

The Spicate Eugenia flowers infrequently - sometimes once to three times a year, and occasionally it may flower weakly and the tree does not reach a full bloom. However, when it does flower (and often several trees in the same vicinity flower together at once), the butterfly species that visit the flowers for their nectar is an awesome sight to behold! Where the tree grows at the fringes of the nature reserves, many rare and otherwise not-often-encountered species can be observed.

Butterflies of all sizes and species are attracted to the flowers of the Spicate Eugenia

A tree in full bloom attracts many representatives from five of the six families of butterflies in Singapore - with the exception being the Riodinidae, which I have personally not encountered any of the species feeding on the flowers of the Spicate Eugenia. It is interesting to note that the physical structure of the flowers are almost universal to allow butterflies of all shapes and sizes to feed on the nectar in the flowers - from the large Papilionidae to the diminutive Lycaenidae and the long-proboscis endowed Hesperiidae.

Very subtle differences between the leaf margin veins between S. zeylanicum and S. lineatum

The Spicate Eugenia is often confused with the very similar-looking Common Kelat (Syzygium lineatum). Both trees, when flowering, are equally as attractive to butterflies. The distinguishing veins on the underside of the leaf of the Common Kelat has two veins running parallel to the leaf margin, whereas the Spicate Eugenia's leaf has only one vein.

Another closely-related species, Syzygium glaucum and some butterflies that feed on the flowers

Another related species, Syzygium glaucum, has almost similar looking flowers that are equally attractive to butterflies and is also featured here with several butterfly species feeding on the flowers. This Syzygium species has been cultivated at Pasir Ris Park near the mangrove walk, and should also be observed for its attractiveness to the butterflies in this urban park.

Whilst the fragrance of the flowers is not often detectable by the human nose, once the Spicate Eugenia trees or bushes flower, particularly in nature areas, it will be swarming with butterflies, bees, moths and all sorts of insects. This strongly suggests that the nectar in the flowers must be attractive enough to bring all these visitors, which are otherwise shy and not often observed, to the flowering trees.

The usually shade-loving Archdukes come out to feed on the flower of the Spicate Eugenia.
Top : Male Archduke Bottom : Female Archduke

It is always amazing to see so many species of butterflies visiting the flowers of the Spicate Eugenia, and even the ground feeders can be seen. For example, the Archduke (Lexias pardalis dirteana), usually found in the shaded understorey of forested areas and typically feed on rotting fruits on the forest floor, has been seen feeding at the flowers of the Syzygium in the open. This observation is evidence of a change in behaviour of the shade-preferring Archdukes, whenever they are attracted to the flowers of this plant.

Various Hesperiidae and Lycaenidae feed on the Spicate Eugenia flowers

For the many other species of butterflies which an observer may encounter when the Spicate Eugenia (and several other related Syzygium spp) flowers, there are too many to name in this article. We will continue to be surprised at the diversity of butterflies that are attracted to this flowering tree and it is certain one of the 'butterfly magnets' that NParks should continue to cultivate, particularly in the vicinity of the nature catchments.

Text by Khew SK : Photos by Khew SK, Henry Koh, Loke PF, Bene Tay and Teo Siyang

21 January 2018

Aberrations in Butterflies

Aberrations in Butterflies
Variations and abnormalities in butterflies

About 10 years ago, an aberration of the Common Rose which has missing hindwing white patches of the normal species appeared in Singapore.  Whilst the status of this variation/form/aberration was unknown, several generations of this black hindwing Rose continued for some time before mysteriously disappearing again. With several similar individuals appearing for some time, it could be a subspecies or a different species, but its disappearance raises some doubt as to whether this "aberration" was caused by genetic or environmental triggers? *1

In the animal kingdom, abnormalities caused by genetic mutations or disorders give rise to aberrations or mutations that are physically different from the norm. The more well-known disorders like albinism (the lack of pigmentation in humans and animals), dwarfism (severely restricted growth, leading to smaller than usual individuals), Down's Syndrome (intellectual disability and characteristic facial appearance), polymelia (born with additional appendages) and too many others to discuss here, have been well-documented in genetic science.

An aberrant Malay Viscount with suffused white markings on the forewings

Aberrations in the butterfly world are not rare as thought. The number of photographs of aberrant butterflies that can be found on the Internet, ranging from minor to extreme aberrations in wing patterns and shapes, is evidence that aberrations are relatively regularly encountered in the field. An aberration is a variation in the wing pattern of a butterfly species which is different in some way to the normal pattern. This can occur as a genetic or environmentally produced/induced variation of the usual form of the species. Some aberrant forms although rare, recur on a fairly regular basis and have been documented as new "forms" of a butterfly species.

An aberration of the Branded Imperial where the dorsal side of the hindwing appears to be orange.  In normally-coloured individuals, the dorsal side of the hindwing is black.

Butterfly aberrations may occur for a variety of reasons - for example, extreme temperature changes especially while the butterfly is developing during the pupal (chrysalis) stage may cause aberrations to occur. Very cold conditions can produce very dark forms of some species while heat shock may cause dramatic changes in wing pattern. Research that subject pupae to cold shock have yielded a wide variety of aberrant patterns and colours in butterflies' wings. In some extreme research, chemical injections into caterpillars and pupae to catalyse change in the butterflies' wing patterns have also been carried out in controlled environments.

An extreme aberration of a Common Bluebottle where almost all the blue pigment is missing from the wings

This article discusses and showcases examples of aberrant butterflies that have been observed in the field, that appear different from normal individuals of the species. Amongst the Papilionidae, there have been cases of minor variations observed. However, one such case stands out as a striking example of an extreme aberration. In the case of the Bluebottle (Graphium sarpedon luctatius) encountered, the macular band across both wings has merged with the wing borders and the absence of the usual blue colour gives it a totally different appearance from the norm.

An aberrant Common Grass Yellow (left) with no cell spots

Minor aberrations in the spots of the Eurema spp. is quite regularly encountered in Singapore. The absence of the diagnostic cell spots in these Grass Yellows often cause confusion as to what species has been observed. In the example shown above, this aberrant Common Grass Yellow (Eurema hecabe contubernalis) shows a total absence of its cell spots and the lack of other spots and features on the wings make it appear like a different species from the normal butterfly.

The Ypthima species are well-known for having aberrant individuals with additional ocelli on the hindwings

Amongst the Satyrinae, aberrations in the form of additional ocelli has been regularly documented in the Ypthima spp. Examples of the Common Three Ring and Common Five Ring are encountered so regularly with additional ocelli that this phenomenon is taken as "normal" that some individuals sport these extra eyespots.

An aberration of the Malayan Bush Brown with a thick, dark marginal border on both wings

This strange looking aberrant Malayan Bush Brown (Mycalesis fusca fusca) sports a marginal black band on both its wings. A normal individual does not have this dark band, but instead has marginal and submarginal zigzag lines which are completely absent in the aberrant individual.

An aberrant Peacock Pansy with very much reduced or absent hindwing ocelli

This aberrant Peacock Pansy (Junonia almana javana) with a reduced or absent large ocellus on the hindwing makes it appear very different from a normal individual of the same species. The ocelli on the forewing also lack the blue and white highlights of a normal Peacock Pansy.

An aberrant Malay Viscount with abnormal forewing markings that make it look very different from a normal individual of the species

This rare aberrant Malay Viscount (Tanaecia pelea pelea) with the highly diffused forewing markings and reduced cell spots makes it appear like a different species at a glance, when compared with a normal individual of the same species. In this case, the aberrations are limited to the forewings only, as the hindwings appear quite normal with the usual markings of the species.

Various aberrations (left, middle) of the Common Hedge Blue

Aberrations amongst the Lycaenidae appear to be quite regular amongst the Polyommatinae species. The variations in these aberrant individuals can range from a heavily darkened wings with heavier markings to additional spots and diffused striations that make the aberrant individual appear like a totally different species. In the example above, the Common Hedge Blue (Acytolepis puspa lambi) on the extreme left appears very different from the normal example on the right. The middle specimen has conjoined spots on the hindwing.

Aberrant markings of the Malayan (left, middle) which give the individuals a much darker and busier appearance than the normal appearance of the species

The Malayan (Megisba malaya sikkima) depicted above also shows a range of variations from left to right, showing examples of melanism in their wings that suggests a different species, if not carefully scrutinised.

An extreme aberration of the Pointed Line Blue (left) gives it an appearance of a different species

This example of a Pointed Ciliate Blue (Anthene lycaenina miya), an aberration with distinct diffuse white markings on both wings makes it appear very different from a normal individual of the same species.

The large black apical hindwing spot and thicker markings on this aberrant Cycad Blue makes it appear very different from a normal individual of the species

The aberrant Cycad Blue (Chilades pandava pandava) with an extra large black apical spot on the hindwing and the suffused markings on both wings depart quite significantly from the normal butterfly's wing markings.

The large hindwing patch on this aberrant female Quedara monteithii monteithii suggests a different species from what it should look like

And finally, amongst the Hesperiidae (Skippers), aberrations are also known to occur. This bred female of Quedara monteithii monteithii appears to have an extra white patch on its hindwings, whereas a normal female features an all-brown hindwing. The aberrant female appears like a different species.

The complete absence of the arrow-shaped black spots on this aberrant Plain Palm Dart, and the paler orange colour makes it look like a totally different species from the normal individual of this skipper

In the above example of a Plain Palm Dart (Cephrenes acalle niasicus) this aberrant individual lacks any of the normal black arrow-shaped markings of a normal individual of this species. Its paler than usual orange colour for this male plus the strange patch that lacks any wing scales whatsoever gives this aberrant individual a very strange appearance.

Text by Khew SK  : Photos by David Chan, Chng CK, Jerome Chua, Khew SK, Bobby Mun, Simon Sng, Michael Soh, Horace Tan, Tea Yi Kai and Benjamin Yam

*1 : Notes on Pachliopta antiphus (Black Common Rose) - The taxonomic position of antiphus is uncertain. It is regarded as conspecific with Atrophaneura aristolochiae by Tsukada and Nishiyama (1982) and Fujioka et al. and but recognized as a separate species by Page & Treadaway (1995). Papilio aristolochiae subspecies poseidippus Fruhstorfer, 1911 and Papilio aristolochiae subspecies kameiros Fruhstorfer, 1911 are both treated as junior synonyms of Pachliopta antiphus antiphus (Fabricius, 1793) by Page & Treadaway (1995)

14 January 2018

Butterfly of the Month - January 2018

Butterfly of the Month - January 2018
The Tawny Coster (Acraea terpsicore)

Mating pair of Tawny Costers - top : male, bottom : female

Here we are, right in the middle of the first month of 2018, and we continue with our feature-butterfly monthly series into its 11th year. The weather is uncharacteristically odd in Singapore for this time of the year and we are enjoying (?) sub-23 deg C temperatures on most days, with the lowest temperature of 21.4 degC recorded in western Singapore in recent years. The persistent wet weather over the past week added to the cold snap as airconditioners were turned off, and tumble dryers doing their fair share to keep the laundry nice and dry.

A taste of climate change to come? The exceptional rain on 8 Jan dumped so much water over the eastern part of Singapore over a couple of hours that the drainage system was unable to cope with the sudden downpour. The ensuing floods in some of the low-lying areas created the first major traffic snarl for the year, coupled with half-submerged cars and damaged properties.

The residents in the eastern US will probably think that a puddle of water in Singapore is nothing compared to the 'bomb cyclone' that dropped a whole load of snow on them. Sub-zero temperatures and foot-high snow closed airports in New York and kept the kids from schools. Even in the warmer south of the US, in Florida, the sudden cold weather caused near-frozen iguanas to drop from trees! So far, we haven't had any records of our local changeable lizards dropping off our trees yet.

The cold and wet weather has kept our local butterfly-watchers indoors as there is very low butterfly activity out in the field anyway. We look forward to warmer weather and bluer skies in the coming months where we can go out and enjoy the beauty of nature's flying jewels again soon. Until then, we can only ponder on the effects of climate change, and what the impacts are, to our environment and biodiversity.

And so we turn to our January Butterfly of the Month, the Tawny Coster (Acreae terpsicore). This species did not appear in Singapore until some time back in 2006. After it reached the shores of Singapore, we postulated its likely voyage all the way from the Indian subcontinent, through Thailand and Peninsula Malaysia. Subsequently, it was spotted in Indonesia, and it is believed to have colonised part of Australia as well. A very tenacious butterfly indeed!

Tawny Coster perched with wings folded upright when resting

Before 2006, it was first spotted by collectors in the northern states of West Malaysia in 1992 as it progressively made its way down the peninsula over the span of at least a decade. The species' journey is most likely aided by the easy availability of its caterpillar host plants, Passiflora foetida, Passiflora edulis and Passiflora suberosa - all fast-growing Passion Fruit vines that are spread by birds that eat their fruits. Its caterpillars were also found on Tuneria ulmifolia another plant of the Passion Fruit family, and it is highly likely that its caterpillars can also feed on other species of Passifloraceae.

Top : Upperside of male Tawny Coster ; Bottom : Upperside of female Tawny Coster

The male Tawny Coster is a deep orange on its upperside whilst the female is a paler orange-yellow. There is a transverse black spot in the cell of the forewing. The underside is generally of a lighter shade of orange with a larger number of black spots on both wings compared to the upperside. There is a marginal row of black-bordered white spots giving the termen of the hindwing a scalloped appearance.

Mating pair of Tawny Coster - Left : female Right: male

The butterfly has a relatively slow flight, usually fluttering restlessly as it moves around to feed on various nectaring sources. Occasionally, it will stop to rest on twigs or upper surfaces of leaves with its wings folded upright. Most of the time, when it stops to feed on flowers, it tends to keep its wings open for balance.

The Tawny Coster is now a permanent extant species in Singapore and is quite common in urban parks and gardens and in undeveloped wastelands where its preferred caterpillar host plant, Passiflora foetida can be found. One of the reasons why this species is so successful may be the way the female lays its eggs - often up to 50 at one sitting and the purported distastefulness of both its caterpillars and adult butterflies.

A newly-eclosed male Tawny Coster holding on to its pupal case

The butterfly is believed to display aposematic colouration in being brightly-coloured and conspicuous. It is likely to be distasteful to birds, as are several other butterfly species that feed on Passifloraceae, e.g. the Lacewings (Cethosia spp). However, it is not immune to attacks from reptiles and mantises - as shown in the photo below where a mantis has ripped off the head of a Tawny Coster that it captured and is eating.

Text by Khew SK : Photos by Bob Cheong, David Chan, Chng CK, Khew SK, Loke PF, Anthony Wong, Mark Wong and Benjamin Yam