31 December 2022

Butterfly of the Month - December 2022

Butterfly of the Month - December 2022
The Barred Line Blue (Prosotas aluta nanda)

A Barred Line Blue on tiptoe puddling at a sandy streambank in the nature reserves of Singapore

December and Christmas Day 2022 have come and gone, and we are in the final hours of a tumultuous year that is probably best remembered for its unprecedented upheavals in world events. For most countries, 2022, the third year of the Covid19 pandemic, was all about opening up, living with Covid and dealing with other more pressing livelihood issues like inflation, rising rents and interest rates and escalating costs of daily essentials.

Countries like Ukraine had to face the spectre of war sufferings and the painful uncertainty of when life would go back to a peaceful existence without the fear of getting one's home bombed out. After almost a year, it would appear that the war will continue, despite efforts for peaceful negotiations and sanctions imposed on Russia. It is likely that hostilities will continue into 2023 with neither side willing to call a truce. And human lives will continue to be sacrificed in the name of sovereignty.

China's Zero-Covid management began to crack under the pressure of public protests and the prospects of further damage to their already battered economy in the coming year. A much-awaited announcement of opening up and removing quarantine requirements lent some cheer and optimism to the Chinese in late December. It is probably the last large economy to announce that it was finally willing to "live with Covid" and get on with life, like the rest of the world had already done so for most part of 2022.

For soccer fans around the world, World Cup 2022 in Qatar was a nice distraction from the daily dose of news of unhappy happenings all around the world. This must be the first time the World Cup had to be held at this time of the year instead of during the summer months. In the harsh climate of the Arab world which comprises mainly low-lying deserts, it would have been unbearable to hold the matches in the scorching summer temperatures that exceed 40 degC. Argentina were crowned the champions after winning the final against the title holder France 4–2 on penalties following a 3–3 draw after extra time.

Our Butterfly of the Month for December 2022, and to close out the year, is the recently-discovered Lycaenidae - The Barred Line Blue (Prosotas aluta nanda). Records show that the earliest photographed individual of this species in Singapore dates back to Feb 2008. However, it was not validated until more sightings and photographic records of this species were available in recent years. The Barred Line Blue was not listed in the checklists of the early reference authors and hence recorded as a "non-native" species.

With its non-remarkable grey undersides and white striae, the Barred Line Blue may have been missed or mistaken as one of the lookalike Nacaduba cousins that are extant in Singapore. Its resemblance to several of the more common Six Line Blues may have caused it to be missed by the early authors. This species has been more often encountered puddling at muddy streambanks than at flowering plants. Females are presumably much rarer.

The male Barred Line Blue is blue on the upperside whilst the female has wide brown borders with a pale bluish-green patch on the forewing. The eyes are jet-black and opaque and the eyes and palpi are particularly hairy. The body of the antennae are black-and-white, with the clubbed end of each antennae white tipped.

The diagnostic feature of the Barred Line Blue is the post-discal striae in space 3 of the forewing below. This striae is shifted slightly towards the base of the wing compared to its adjacent striae in spaces 2 and 4. The hindwing has a black white-tipped filamentous tail emerging from vein 2. The orange-crowned black tornal spot on the hindwing is large and prominent.

The Barred Line Blue has a quick erratic flight and is usually skittish, as is the case with the other species in the Prosotas and Nacaduba genera. Thus far, most of the sightings of this species have been in the forested nature reserves, and more often, males are encountered puddling at sandy streambanks on hot sunny days, usually attracted to decomposing animal matter or excretions. Other sightings are of the butterfly feeding on flowering plants at the edges or within the forested nature reserves.

On this final day of 2022, I would like to wish all our readers from all over the world a Happy New Year 2023 and May all your Butterfly Wishes come true in the year ahead! 

Text by Khew SK : Photos by Huang CJ, Khew SK, Koh CH, Loh MY, Loke PF, Low JK, Aaron Soh, Zick Soh and Mark Wong