Variation or Form?

Variation or Form?
Observation Notes on 3 Singapore Butterflies

A Common Tit puddles on a small stone.  The forewing is grey and weakly shaded with ochreous brown along the termen

In an earlier discussion on dimorphism and polymorphism in butterflies, we saw that in some species of butterflies, one or both sexes occur in two or more discontinuous forms due to a difference in their genetic constitution. Unlike seasonal forms (which are uncommon in Southeast Asian butterflies) which are physically differentiated primarily due to environmental factors, the forms that are caused by genetic variation are called morphs and usually given separate names.

A male Colour Sergeant perches on a leaf in a sunlit spot.  Note the orange subapical spot on the upperside of the forewing

The more obvious species that are dimorphic or polymorphic in either the males or females are well documented. Some examples are the Common Mormon (Papilio polytes romulus), of which the females occur in two forms, the Plain Tiger (Danaus chrysippus chrysippus), which occurs in two forms, and the Malay Baron (Euthalia monina monina) in which the male occurs in at least 3-4 different forms.

A female Blue Pansy with the typical brown hindwing colour

With observations over the past 3-4 decades of butterfly watching in Singapore, there are a few species that warrant closer observations for potential dimorphism. Although undocumented, these species may be good subjects for scientific research as to whether the regular variations observed suggest the possibility of a divergence in the physical characteristics of the species such that they may be considered dimorphic. These species are discussed below :

1) The male Colour Sergeant (Athyma nefte subrata)

A male Colour Sergeant with orange subapical spot.  This individual was photographed at Mt Faber Park

Sexual dimorphism is well documented in the females of the Colour Sergeant where the females occur in two distinct forms - the orange coloured form-neftina and the brown coloured form-subrata. That the females of the species occurs in two different forms is not in doubt. However, observations of the males of the Colour Sergeant poses some questions about the consistent variation (albeit a subtle one) in the colour of the subapical spot on the upperside of the forewing.

A male Colour Sergeant with white subapical spots on the forewing.  This individual was photographed at Telok Blangah Hill Park

A male Colour Sergeant with orange subapical spots on the forewing.  This individual was photographed at Ulu Sembawang Park Connector

The typical male, as described, is rich velvety black with the white markings tinged with bluish. The apical spot in space 6 of the forewing is usually white, but individuals have been recorded here in Singapore where this spot is more than just "tinged with orange". In some examples shown here, the spot is quite large and distinctly orange - even in bred specimens.

A male Orange Staff Sergeant (Athyma cama gynea) with orange subapical spots on the forewing.  This species is not found in Singapore and prefers montane habitats.

A newly-eclosed bred male Colour Sergeant with orange subapical spots on the forewing

A male Colour Sergeant with white subapical spots on the forewing.  This individual was photographed at Telok Blangah Hill Park

The variation of this subapical spot ranges from totally white with no trace of orange, to almost orange, with a range of variations in-between. This is contrasted with the similar-looking Orange Staff Sergeant (Athyma cama gynea) which is montane and does not occur in Singapore, where the subapical spot is orange. Would it be possible that the male Colour Sergeant occurs in two "forms" - one with the white subapical spot, and the other with an orange subapical spot? Or is the difference in the colour of this spot too insignificant for the male to be considered dimorphic?

2) The female Blue Pansy (Junonia orithya wallacei)

A typical female Blue Pansy with all-brown hindwings

This common urban species is widely distributed in Singapore, primarily due to the abundance of its caterpillar host plant, the Chinese Violet (Asystasia gangetica). The male is distinctive, with its attractive bright blue hindwing and cannot be confused with any other species in the region. The female, which is described as coloured with more sombre hues, and has a half bluish-grey hindwing.

A female Blue Pansy with extensive blue shading on the hindwing

A female Blue Pansy with a moderate blue shading on the hindwing

A female Blue Pansy with almost all-brown hindwing, and only slight blue shading at the dorsum of the hindwing

The colour of the hindwing of the female ranges from the post-discal half of the hindwing blue to totally brown with no hint of blue at all. Whilst the diagnostic pair of large orange-red post-discal ocelli on the hindwing is always consistent, it is the colour of the hindwing that may offer some interest to researchers to dwell further on the subject of whether the female Blue Pansy could be dimorphic.

A pair of Blue Pansy (left : male and right : female).  The female has all-brown hindwings

An all-brown hindwinged female Blue Pansy

A female Blue Pansy with strong blue shading on the hindwing

Whilst the extent of the blue colour on the hindwing of the female Blue Pansy is variable, the occurrence of totally brown females with no blue presents a question of whether there could be genetic variation at work that could point to some form of dimorphism in the females. As there are no distinct seasonality of the occurrence of the blue and brown hindwinged females, it is unlikely to be a subject of dry or wet season forms here.

3) The Common Tit (Hypolycaena erylus teatus)

A Common Tit displaying the typical pale greenish grey underside with slight ochreous brown termen and orange post-discal bands on the underside of the wings

This small and common urban species can be found in Singapore's parks and gardens as well as on the fringes of the forested nature reserves. In this species, the range of the colour of the underside of the forewing ranges from pale greenish grey with "weakly shaded with ochreous brown along the termen" to a very strong and obvious orange shading appearing like a submarginal band on the forewing.

Another typical "grey form" of the Common Tit with slight orange shading along the termen of the forewing underside

An "orange form" of the Common Tit with extensive orange shading on the underside of the forewing, making it appear like a band along the termen margin

A Common Tit with extensive orange shading across both wings

In some pristine individuals, the orange underside is so distinct as to even closely resemble the related species, the Dark Tit (Hypolycaena thecloides thecloides) whose underside of the wings are consistently orange. At the other end of the spectrum, there are individuals of the Common Tit that appear almost grey, with the post-discal bands a deeper orange-brown compared to the brighter orange bands in the orange "form".

Another Common Tit with strong orange shading along the termen of the forewing

A Common Tit with slight orange shading at the termen of the forewing

A Common Tit with minimal orange shading along the termen, making it appear grey compared to the extensive orange "form"

Would the variations in the colour of the underside of this species suggest some form of dimorphism? Individuals of the orange or grey "forms" appear consistently enough to imply that these are not aberrations. Is there a possibility of two different forms of the Common Tit? This is a subject that may be worth pursuing by researchers who are keen to take this observation further.

The observations here are for discussion, and certainly does not claim to be conclusive with any scientific rigour. The possibilities of dimorphism of these species with distinct forms will have to be researched and studied further.  But the observations are intended to spark off further thoughts and considerations for those who may be interested to find out more.

Text by Khew SK : Photos by Foo JL, Khew SK, Lim CA, Loh MY, Michael Soh, Horace Tan and Anthony Wong  

Butterfly of the Month - August 2020

Butterfly of the Month - August 2020
The Yellow Grass Dart (Taractrocera archias quinta)


A mating pair of Yellow Grass Darts

We are now into August 2020, and the pandemic continues to haunt the world. We are contemplating the "new norm" as our lives have to adapt and evolve to accommodate the way we work, live, learn and play. Today, the term WFH (Work From Home) is immediately understood by everyone, people are familiar with online shopping and ordering food, students have come to terms with attending lectures on online platforms under home-based learning programmes, and so on.

Typical skipper sunbathing pose with the forewings held at an angle and the hindwings opened flat

For those of us who travel around the world, whether for work or leisure, will find that the "new norm" will make travelling by air a very different experience from now on. Just as air travel changed (and inconvenienced everyone) after the 911 attack in the US, the COVID-19 effect will certainly transform the whole aviation industry in the way we travel from place to place in future.

Personal protection equipment on flights, like face masks, will be the standard once inter-country travel restrictions are lifted. As would be temperature checks, health checks, swabbing and a myriad of other unprecedented procedures and processes that will make air travel very inconvenient and probably uncomfortable. The prospects of having to be quarantined for the mandatory 14 days if one is found unwell when reaching the destination country would probably be something that travellers would have to contend with, in future.

Over in Singapore, the battered economy is taking time to heal itself, as the government extended a financial helping hand to businesses severely affected by the pandemic. Those on the front line of the aviation, tourism, F&B, commercial sectors were the hardest hit and needed help most. The migrant workers' crisis that specifically hit Singapore worst, severely affected the built environment sector and had a cascading effect on consultants, suppliers and contractors.

This month, we introduce another skipper from the genus Taractrocera. We earlier featured the Spotted Grass Dart as our April 2020 Butterfly of the Month. Our August 2020 Butterfly of the Month is the other Singapore-extant species from this genus, the Yellow Grass Dart (Taractrocera archias quinta).

A Yellow Grass Dart feeding on the purple flower of the Elephant's Foot weed

A Yellow Grass Dart sunbathes on a blade of grass.  Note the antennae and the lack of the apiculus (hook) that most other skippers have

The Yellow Grass Dart is a new discovery for Singapore, as it was not recorded on the early reference checklists. It was first documented as a new find back in August 2004, and is now featured as our butterfly of the month for August 2020, sixteen years later. The species continued to be regularly observed, mainly within the nature reserves of Singapore, and along the fringes and buffer areas adjacent to the nature reserves, such that it has been confidently considered as an extant species in Singapore.

A Yellow Grass Dart perches on a blade of grass in the early morning hours

The distinctive feature of the Taractrocera genus is the absence of an apiculus (hook) on the antennae that is typical of the Hesperiidae family (Skippers). Of the two species found here, the Spotted Grass Dart was recorded as "not having been taken in the last century (from 1801-1900)". It was considered extinct in Singapore until it was regularly observed again from 1990s till today. The Yellow Grass Dart, however, was only discovered in 2004 and is technically classified as a non-native or exotic species.



The Yellow Grass Dart is a small butterfly, with an average wingspan of between 20-24mm. It resembles the orange-and-black Potanthus species and indeed often found flying in the same localities. Like the Potanthus species, the Yellow Grass Dart has a rapid darting flight but generally keeps at low levels amongst grassy plains where it flies and feeds on wildflowers.


A Yellow Grass Dart feeding on the flower of the Singapore Daisy

The Yellow Grass Dart is dark brown above, with orange spots and streaks on the fore- and hindwings. The orange markings form a continuous streak from the base to the costa of the forewing above. The underside is paler and the orange markings more extensive. The hindwing cilia are not chequered and of the same orange colour as the other markings on the wings.




To all our Singaporean readers, a Happy 55th National Day and here's to many more years of appreciating, watching and photographing Nature's Flying Jewels on our biodiversity-rich little island in the sun!

Text by Khew SK : Photos by Khew SK, Loke PF and Michael Soh

Plushblues of Singapore

The Plushblues of Singapore
Featuring the Flos species in Singapore


A Darky Plushblue perches on some flower buds in the shaded forest understorey

The genus Flos, collectively called the Plushblues, showcases some of the most attractive Lycaenidae species with iridescent ultramarine blue uppersides. Unfortunately, all the species rarely sunbathe with their wings fully opened, and one often only gets a glimpse of its attractive blue uppersides. Globally, there are 15 species of Flos recorded, although some researchers have re-classified at least one species of Arhopala under Flos after studies of its early stages and morphology.

A Plain Plushblue feeds on the sweet secretions on the stem of a Rattlebox weed

A Bifid Plushblue perches on a leaf

There are four Flos species extant in Singapore, and only one can be regularly found in urban parks and gardens. The other three are rare, often encountered singly, and forest-dependent species. They usually prefer the shaded understorey of the forested nature reserves of Singapore. The genus is related to the Arhopala and sometimes found in the same heavily-shaded localities.

A Shining Plushblue perches at the edge of a leaf

The Plushblues are generally skittish and easily spooked. They fly quite rapidly and settle on the top surfaces of leaves to perch with their wings folded upright. The underside of the Plushblues is dark purple brown with cryptic bands and spots on both wings. In some of the species, there is a patch of deep red or crimson at the wing bases.

1. The Plain Plushblue (Flos apidanus saturatus)

The Plain Plushblue is the only Flos species that can be found in urban parks and gardens more often than in the forested areas. It is skittish and flies rapidly amongst the shrubbery. It can sometimes be observed feeding on the sap of stems and branches. It stops to rest on tops of leaves with its wings folded upright.

A male Plain Plushblue shows its ultramarine blue uppersides

A Plain Plushblue feeding on the ripened fruits of the Singapore Rhododendron

The male Plain Plushblue is a deep ultramarine on its uppersides, with a thin forewing border. The female is a shining blue with broad black borders on both wings. The underside is a pale purple brown with dark markings across both wings. In pristine individuals, there is often a deep red patch at the base of both wings. The hindwing bears a stubby white-tipped tail at vein 2 and is toothed at veins 1b and 3. There are pale green iridescent scales at the tornal eyespots on the underside of the hindwing.

2. The Bifid Plushblue (Flos diardi capeta)

A Bifid Plushblue feeding on the ripened fruits of the Singapore Rhododendron

The Bifid Plushblue is mainly found in the forested nature reserves of Singapore, and is not seen in urban gardens. Other than the Plain Plushblue, all the other three species are considered rare and usually occur singly in heavily shaded habitats. It is a strong flyer and alert to movements. It is one of the Plushblues of which the female is more regularly observed to sunbathe with wings opened.

A female Bifid Plushblue opens her wings to sunbathe

A Bifid Plushblue shares the sugars from the ripened fruits of the Singapore Rhododendron with an ant

The male Bifid Plushblue is a dark purple-blue above with thin black borders. The female is a paler purple-blue with broad black borders on both the fore- and hindwings. The underside is cryptic in appearance, with dark brown and pale markings. There is a characteristic "V" shaped costal spot that is not connected to the other brown markings on the hindwing that separates this species from the other Plushblues. There is a white-tipped tail at vein 2 of the hindwing and is toothed at veins 1b and 3. The pale green iridescent scales at the tornal area is more extensive that the other species in the genus.

3. The Shining Plushblue (Flos fulgida singhapura)

A Shining Plushblue perches on a leaf in the shaded understorey in the nature reserves

This 3rd Plushblue has the distinction of bearing the word "Singapore" in Malay in its subspecies name. It is a rare forest-dependent species and prefers the heavily-shaded forest understorey in the nature reserves of Singapore. Also another skittish and rapid-flying species, it tends to prefer to fly closer to the ground and stop on the tops of leaves until disturbed.

A newly-eclosed male Shining Plushblue

A newly-eclosed male Shining Plushblue opens his wings to sunbathe

The Shining Plushblue can easily be distinguished from its other cousins in that it has a shorter stumpy tail at vein 2 of the hindwing, and is correspondingly toothed at veins 1b and 3. It is darker in appearance on the underside, and has a dark brown band stretching from costa to base. The males are deep ultramarine blue on the upperside, whilst females are shining blue with broad black borders.

4. The Darky Plushblue (Flos anniella anniella)

A Darky Plushblue perches at the edge of a leaf

The last Plushblue is considered the rarest of the four, and also prefers heavily-shaded forested habitats in the nature reserves of Singapore. It is the least encountered of the four Plushblues and has the same skittish disposition and rapid flight of its other relatives in the genus. It has been bred on various species of Lithocarpus which is a preferred genus on which the other Flos species (except Flos apidanus) feeds.

The Darky Plushblue is tailless, unlike the other 3 species, but the hindwing is toothed at veins 2 and 3. The upperside of the male is a lustrous violet blue with a thin black border. Females are lighter purple with broad black borders on both wings. The underside is mostly dark purple brown with white edging on the darker brown bands. The apical area is distinctly whitened, whilst the iridescent scaling at the tornal area of the hindwing is the least distinct amongst the four species.

Text by Khew SK : Photos by Huang CJ, Khew SK, Loh MY and Horace Tan