31 October 2009

Of Saws and Teeth

Of Saws and Teeth
The Sawtooth Butterflies

I've always wondered about the English Common names of the two species from the genus Prioneris. These large and robust butterflies found in Malaysia, belong to the family Pieridae. The two species, Prioneris philonome themana is known as the RedSpot Sawtooth whilst its close relative Prioneris thestylis malaccana is called the Spotted Sawtooth.

A RedSpot Sawtooth puddling at Endau Rompin Nature Reserve, Malaysia

Both the species are large butterflies and resemble the Appias (Albatrosses) and the Delias (Jezebels), to which they are relatively related. However, the Sawtooths are powerful flyers and are fast on the wing.

Another RedSpot Sawtooth puddling on damp ground

Both species are white above with the veins blackened in the outer margin areas The RedSpot Sawtooth has the hindwing basal two-thirds yellow, with a small red basal patch. The veins are prominently darkened. Its cousin, the Spotted Sawtooth is similar but has the entire hindwing yellow.

A RedSpot Sawtooth and a Blue Jay puddling on a sandy river bank

The RedSpot Sawtooth is the more common of the two species, and is found in the forested areas of Malaysia, often puddling with other Pierids and Papilionids. The Spotted Sawtooth prefers higher elevations but also has the same propensity for puddling at damp sandy stream banks tainted with animal urine and other decomposing organic matter.

A Spotted Sawtooth puddling next to a Chocolate Albatross

Coming back to the common name of "Sawtooth", it only dawned on me when I enlarged a shot that I took of the Spotted Sawtooth during post-processing, and I noticed the costa (or the leading edge) of the forewing. In the highly magnified view, one can observe that the wing edge is actually serrated with a series of sharp 'teeth' like the blade of a saw!

A Spotted Sawtooth puddling on tainted sand at Fraser's Hill

So now we may have stumbled upon one of the possible reasons behind why the early English collectors christened these two butterflies with the name of "Sawtooth". Click on the photo below to get a larger view of the serrated forewing of the butterfly's wing and you can see the details of the saw-like edge.

Text by Khew SK : Photos by Khew SK ; LC Goh & Sunny Chir

28 October 2009

Two Blues Make it 290

Two Blues Make it 290
Update to the Butterflies of Singapore Species Checklist

The Glistening Caerulean (Jamides elpis pseudelpis)

After our last re-discovery report on the Moth Butterfly, which raised the number of butterfly species found in Singapore to 288, this update adds on two more species to the Singapore Checklist. Both these Lycaenidae were originally listed in the database of species from the early authors based on their checklists found in Butterflies of the Malay Peninsula Edition 4 by Corbet & Pendlebury, and Butterflies of West Malaysia and Singapore by WA Fleming.

The Large Four Line Blue (Nacaduba pactolus odon)

The reference checklists in C&P4 and Fleming's books form the baseline species checklists for butterflies of West Malaysia and Singapore. The journal article "Updating The Butterflies of the Malay Peninsula" in the Malayan Nature Journal in 2006, Vol 59 Part I, pages 1-49 records some of the more recent revisions. The first draft of this article was produced by Col JN Eliot just before his untimely death on 11 Apr 2003. The article was edited, enlarged and prepared for final publication by Henry Barlow, Richard Eliot, Laurence G Kirton and RI Vane-Wright - all experts in the field of butterflies of the region. This journal article adds to the baseline checklists and updates the more recent finds in Malaysia and Singapore in the later part of the 20th century and from 2000-2005.

There has been some recent confusion in the number of species for Singapore, with various authors counting subspecies as well. Based on scientific taxonomic convention in documenting species checklists, this is obviously incorrect. A species is counted only once irrespective of how many subspecies it may have. There have also been uninformed amateurs who insist on using reference books which feature butterflies of other countries in the region e.g. Butterflies of Thailand by Pisuth Ek-Amnuay, to baseline Singapore's species. This is obviously incorrect and misleading. The Thai book, which is an excellent reference for Thailand's butterfly fauna, is obviously not appropriate if used to identify Malaysian or Singaporean butterflies, in particular subspecies.

Two Re-Discovered Lycaenids recorded

Recently, ButterflyCircle members re-discovered two species from the genus Jamides and Nacaduba. These two genera feature many lookalike species which are difficult to identify from field observations. Often, only with good photos and records of the early stages of the species can the species be positively identified.

These two genera feature a number of species from the baseline checklists that have hitherto not been completely re-discovered. This is not to say that some of these species have gone extinct in Singapore, but merely a case of the difficulty of identifying them without proper scientific rigour.

Jamides elpis pseudelpis (Glistening Caerulean)

A female Glistening Caerulean ovipositing on the flowers of Saraca cauliflora

The genus Jamides features a number of species that are similar in appearance and difficult to identify when the butterflies are in flight. Occasionally, individuals are encountered puddling, ovipositing or feeding where good photos are possible, and from these, further confirmation can be made of the identity of the species. Better still, if the early stages are recorded and the caterpillars bred to adulthood.

The male of the Glistening Caerulean (Jamides elpis pseudelpis) is described to be pale shining sky blue above, with the hindwing paler and the underside markings visible from above. The pale blue female has a more prominent black tornal spot which is sometimes faintly orange-crowned. This species belongs to the elpis sub-group of the Jamides, which is characterised by the post-discal band on the hindwing beneath being completely dislocated at vein 3.

Another female Glistening Caerulean ovipositing on an alternative host plant's flower buds

The species has a wingspan of about 27-30mm where the marginal border on the upperside a thread, and the hindwing bears no submarginal markings. The upperside forewing border of the female ends at the costa.

The Glistening Caerulean was re-discovered by ButterflyCircle member Sunny Chir, after reviewing a shot of a Jamides taken at an urban park, where females were observed ovipositing on the flowers of Saraca cauliflora with another closely- related species the Sky Blue (Jamides caeruleus caeruleus) whose caterpillars also feed on the same flowers.

The early stages were recorded by ButterflyCircle member Horace Tan, and will be subject of a future blog life history article.

The Large Four-Line Blue (Nacaduba pactolus odon)

The second rediscovery belongs to the genus Nacaduba - again another genus with many confusing lookalike species. When in flight, there is no way to distinguish the numerous species that exist in Singapore. However, this species' underside markings are unique enough to be able to render identification with a higher confidence if a well-taken photograph is available.

The Large Four Line Blue belongs to the pavana sub-group in the genus Nacaduba. This sub-group is characterised by the absence of the basal pair of lines on the forewing beneath. The Large Four Line Blue is described as the commonest species in the group, and where the underside stripes are broader and more diffuse that in any other species in the genus.

This shot of a puddling Large Four Line Blue was taken at Pulau Pawai, an SAF live firing island

The male of the Large Four Line Blue is purplish blue with marginal borders of about 1.0mm thick. The female is pale blue with the distal portions almost whitish , and with broad black marginal borders of about 3-4mm thick. On the underside, the space between the post-discal straie are unicolourous and of the ground colour. The species has a wingspan ranging from 29-32mm. Both the males and females have a filamentous white-tipped tail at vein 2 of the hindwing.

The Large Four Line Blue is a fast flyer, the male particularly so, but in the later hours of the day, it flies rapidly and perches on a favourite leaf or twig, returning time and again to the same perch after flying off.

With these two re-discoveries, the Singapore Butterfly Checklist now reaches 290 species. In a forthcoming update, we will feature four more species - one of which is a new taxon for Singapore to further add to the Singapore Checklist.

Text by Khew SK ; Photos by Bobby Mun, Federick Ho, Horace Tan, Khew SK, Robin Ngiam, Sunny Chir & Tan CP
Special Acknowledgments : Dr Laurence Kirton of Forest Research Institute of Malaysia for confirming the ID of Jamides elpis.

25 October 2009

Life History of the No Brand Grass Yellow

Life History of the No Brand Grass Yellow (Eurema brigitta senna)

Butterfly Biodata:
Genus: Eurema
Hübner, 1819
Species: brigitta Stoll, 1780
Subspecies: senna C. & R. Felder, 1865
Wingspan of Adult Butterfly: 28-45mm
Caterpillar Local Host Plants: Cassia mimosoides (Family: Leguminosae, Caesalpinoideae)

A No Brand Grass Yellow resting on its host plant.

Physical Description of Adult Butterfly:
Above, each of the deep lemon-yellow wings has a black border which is regularly scalloped The black border on the forewing is not deeply excavated between veins 2 and 4 as in the other species of the Eurema genus. Underneath, the wings are yellow with freckled brown spots, more on the hindwings than the forewings. There are no cell spots on the forewing - a characteristic that is mainly used to identify the lookalike species in the genus. Males do not have an elongated patch (the brand) above and below the basal portions of the cubital vein on the forewing. The underside of the females are more distinctive in that the hindwings are much paler yellow than the forewings.

A female No Brand Grass Yellow taking nectar. Note the paler hindiwng underside.

A male No Brand Grass Yellow taking nectar.

Field Observations of Butterfly Behaviour: This species is uncommon in Singapore. It was recently re-discovered in an open patch of reclaimed land slated for development. The host plant is not commonly seen, and this may be the reason why this species was not observed for a long time in Singapore. At its natural habitat, the No Brand Grass Yellow fly in rather sizable numbers in the vicinity of the host plants. Typically on a sunny day, the adults can be seen fluttering in the nearby open grassy areas and feeding on wild flowers from time to time. This species has also been sighted in one area on Pulau Ubin.

Early Stages:
The host plant, Cassia mimosoides, is a sub-shrub up to 1.5m high with variable stems, usually puberulent with short curved hairs. Inflorescence is supra-axillary or axillary with one to three yellow flowers. The leaves are pinnate, 3-12cm long and 0.8-1.2cm wide. Each compound leaf has 30-60 pairs of leaflets, each of which is 3-10mm long. The early stages of the No Brand Grass Yellow feed on relatively young leaves of this host plant.

Host plant: Cassia mimosoides growing in a coastal wasteland.

A mating pair of the No Brand Grass Yellow.

The eggs of the No Brand Grass Yellow are laid singly at the upperside of a leaflet or the rachis (main vein of the compound leaf) of the host plant. The long spindle shaped egg is laid standing at one end with a length of about 1.1-1.2m. It is pale yellow in color and has many fine vertical ridges and numerous indistinct and intermittent horizontal ridge lines. The micropylar sits at the tip of the standing egg.

A female No Brand Grass Yellow ovipositing on the compound leaf of its host plant..

Eggs of the No Brand Grass Yellow : far and close-up views.
The egg takes about 2.5 to 3 days to hatch. The newly hatched has a length of about 1.4mm and has a pale yellow head capsule. It has a cylindrical and pale yellowish green body covered with rows of tubercles running lengthwise. Each tubercle has a setae emerging from the middle of it. The two rows of tubercles flanking the dorsal line are much larger with longer satae than the rest. A miniscule droplet of fluid can be found at the tip of each setae. It has been reasoned that the droplets contain chemicals which serve the purpose of repelling parasitic insects. The droplet-bearing setae is a feature present in all five instars of this species.

Two views of a newly hatched caterpillar of the No Brand Grass Yellow, length: 1.4mm.

After hatching, the young caterpillar eats the empty egg shell for its first meal, and then moves on to eat the young leaflets nearby. The growth is moderately paced and the body length reaches about 3.5mm in this 1st instar which lasts for 2.0-2.5 days.

Two view of a 1st instar caterpillar of the No Brand Grass Yellow, length 2.3mm.
Note the fluid droplets evident at the tips of most setae.

Two views of a late 1st Instar caterpillar hours before its moult, length: 3.3mm.

The setae on the 2nd instar caterpillar are proportionately shorter and greater in number. There is a faint dorsal line which is darker than the base color of pale green. A pale white to yellowish band runs laterally along each side of the body. The head capsule is still pale yellowish green.
This instar lasts about 2-2.5 days with the body length reaching 5mm.

Two view of a 2nd instar caterpillar, length: 4.1mm

The 3rd instar caterpillar has a yellowish green body with a green head capsule. Its setae are again proportionately shorter compared to the previous instar. The dark dorsal line and the lateral white/yellowish bands, first appeared in the 2nd instar, have both become more distinct. This instar takes about 2-2.5 days to complete with body length reaching about 9mm.

Two views of 3rd instar caterpillar, early in this stage, length: 4.9mm

Two views of 3rd instar caterpillar, late in this stage, length: 8.8mm.

The appearance of the 4th instar caterpillar is little changed from that of the 3rd instar. The lateral bands take on a greater hint of yellow, thus creating a stronger contrast against the green base color. This instar lasts 2-2.5 days with body length reaching about 15mm.

Two views of a 4th instar caterpillar feeding on a leaflet, early in this stage, length: 9.5mm.

Two views of a 4th instar caterpillar, late in thie stage, length: 14mm

The caterpillars of the No Brand Grass Yellow are neat and meticulous eaters. Typically each caterpillar systematically devours all leaflets (30-60 pairs), one leaflet at a time, on a single compound leaf of Cassia mimosoides before moving on to the next. For each leaflet, a 4th instar or 5th instar caterpillar will methodically start with eating one half of the lamina from the base, and then finish the remaining half by eating from the distal end. The following video clip shows the 2nd half of an eating session on a leaflet by a 4th instar caterpillar.

The 5th and final instar caterpillar resembles the 4th instar caterpillar closely. The one visible change is in the lateral bands which have taken on a striking yellow coloration.
The 5th instar lasts for 3-3.5 days, and the body length reaches up to 25mm.

Two views of a 5th instar caterpillar, newly moulted, length: 15mm.

Two views of a 5th instar caterpillar, length: 20mm.

On the last day of the 5th instar, the body of the caterpillar shortens and changes to a dull shade of dark green. It ceases feeding and comes to rest on the underside of a stem/stalk on the host plant. Here the caterpillar spins a silk pad and a silk girdle, with which the caterpillar soon become immobile in its pre-pupatory pose.

A pre-pupatory larva of the No Brand Grass Yellow on a stem of the host plant.
Note the silk girdle featured at the first 2-3 abdominal segments.
Also the posterior end is secured via claspers to to the silk pad on the stem.

Pupation takes place about 0.5 day later. The pupa secures itself with the same silk girdle as in the pre-pupal stage, but with cremaster replacing claspers in attaching the posterior end to the silk pad on the stem, The thorax of the pupa is compressed and the wing pads join to form a deep keel. The head of the pupa has a short pointed snout at its end. The green pupal body is speckled with dark brown to black spots and patches. Length of pupae: 18-19mm.

The pupation event at 2 times the actual speed. Note the crucial role of the silk girdle in supporting the pupating larva, and the attachment of the cremaster to the silk pad at the 2.47 time mark.

A pupa of the No Brand Grass Yellow.

A mature pupa of the No Brand Grass Yellow.
The now transparent wing pad show s the yellow forewing upperside with its black border

After about 4 days of development, the pupal skin turns translucent as the development within the pupal case comes to an end. The yellow coloration and back borders on the forewing upperside are now discernible. The following day, the adult butterfly emerges from the pupal case.

A newly eclosed No Brand Grass Yellow drying its wings near its pupal case.

A female No Brand Grass Yellow drying its wings on its pupal case.
  • The Butterflies of The Malay Peninsula, A.S. Corbet and H.M. Pendlebury, 4th Edition, The Malayan Nature Society.
  • Butterflies of Thailand, Pisuth Ek-Amnuay, 1st Edition, 2006
Text by Horace Tan, Photos by Khew S K and Horace Tan

21 October 2009

Parasitic Mites on Butterflies

Parasitic Mites on adult butterflies
What are they?

An Arhopala sp with a rather large mite attached to its eye

Occasionally, when out in the field photographing butterflies, members of ButterflyCircle encounter strange red globular attachments to adult butterflies - usually at the head or eye of the butterfly. Curious as to what these little critters are, I searched the internet and found that butterflies do fall victim to certain parasitic mites.

A Tailless Line Blue (Prosotas dubiosa lumpura) with a red mite attached to its head

Another Arhopala sp with a red mite attached to its head

Interestingly, the majority of these encounters affect the smaller butterflies in the Lycaeninae family, even though there are examples from the Riodinidae and Hesperiidae families. So far, we have not encountered these mites on the larger species of butterflies yet. Although theoretically, there should be no reason why these mites could not attach themselves to larger butterflies as well. But by far, there have been more observations of these mites on Arhopala spp than any other butterfly genus.

Parasitic mites on the thorax of a Marbled White in the UK © Adrian Hoskins

In his excellent and informative website Learn about Butterflies, ButterflyCircle member Adrian Hoskins wrote about these mites on the British butterfly the Marbled White (Melanargia galathea), and in the example shown, a number of these mites were attached to the thorax of the butterfly rather than the eye or head, as is the more common occurrence in Singapore. Adrian noted that these mites were of the species Trombidium breei and that "studies have shown that these mites are harmless to the butterfly, having no detectable effect on the flight performance, orientation ability or lifespan".

A parasitic mite on a Hesperiidae. Even fast-flying skippers cannot shake off its little red passenger.

It is interesting to learn that despite being parasitic in nature, these mites have little effect on the lifespan of the butterfly. However, it is not known if the mites found on butterflies here in Singapore are of the same species of mites. Perhaps if a reader of this blog who is an authority on mites may want to contribute his or her knowledge about what these little stowaways are and if they cause any harm to the host butterfly.

Close-up shot of a mite attached to the eye of an Arhopala sp

Indeed, where a butterfly is encountered with one of these mites attached to its eye or head, the flight of the butterfly did not seem abnormal, nor did the butterfly display any discomfort or make any attempt to remove the mite with its legs. These butterflies observed seemed to be able to carry out their normal activity like feeding and flying around without much hindrance.

A mite on the eye of a Branded Imperial (Eooxylides tharis distanti)

In two of the cases shown here, the mites are rather 'skinny' where the legs can be seen. It is not known if the mites actually grow fatter as it feeds off the butterfly or if these are of a different species of mites.

Parasitic mite on the eye of Abisara geza niya. Inset : Close up of the mite. Is this a different species from the fatter mites?

It is likely that these mites lurk on flowers and vegetation where these butterflies frequent, and are able to quickly attach themselves to the butterflies when they stop to rest or feed at flowers. However, why they appear to generally attach themselves to the head/eye region of the butterflies observed in Singapore remains a mystery.

The fact that most of the encounters over the years by ButterflyCircle members show this phenomenon of a single mite attached to a butterfly's head or eye appears to reflect the consistency in which this happens in the field here in Singapore.

Similar-looking mites also parasitise other invertebrates like the Harvestman as is shown at this link.

So when you're out there in the field, observing and photographing butterflies, keep a look out for these little red dots on the butterflies, and record your observations and findings. If you have any clue as to what these species of mites are or how they affect the butterflies that they parasatise upon, do share your views with us.

Text by Khew SK : Photos by Adrian Hoskins, Anthony Wong, Federick Ho, Jason Ng, Horace Tan, Simon Sng, Sum CM & Tan CP.