THE BUTTERFLY: A New Taxon for Singapore!

A New Taxon for Singapore!
Discovery of the Banded Lineblue (Prosotas lutea sivoka)

Our new addition to the Singapore Checklist, Prosotas lutea sivoka

It's rather intriguing that when we least expect it, a species that may have been hiding in certain localised patches of forests in Singapore suddenly turns up out of the blue. In this particular instance, a very small butterfly at that! Last weekend, ButterflyCircle member Federick Ho was out exploring the relatively urban forested area of Bukit Brown cemetery when he came across something that looked strange fluttering amongst the bushes. He managed to take a relatively good shot of it that sufficed to identify it as the Banded Lineblue (Prosotas lutea sivoka)

According to the two tomes about butterflies of Malaysia and Singapore - Corbet & Pendlebury's "Butterflies of the Malay Peninsula (C&P4) and W.A. Fleming's "Butterflies of West Malaysia and Singapore", this species is normally found in primary forest below 2,500 ft. It has not been recorded from Singapore before.

Another shot of a Prosotas lutea sivoka taken at Fraser's Hill in Malaysia for comparison

Another recce trip a couple of days later by ButterflyCircle member Horace Tan also yielded a further sighting of this species at the same location, validating Federick's earlier find. We now add this diminutive Lycaenidae to the Singapore Butterfly Checklist as species #304. Whilst a number of new species to be added to the checklist are still under investigation by various experts, this little Prosotas, that is so distinctly marked as to eliminate any doubt as to its identity, will be henceforth included in the checklist.

A heavily cropped shot of another individual of the new find shot by Horace Tan on a different day

The hindwing subapical spot in space 6 and sometimes in space 5 as well as the two tornal spots, one in space 2 and a much smaller one in space 1b, puts it beyond doubt that this is Prosotas lutea sivoka. It is a new find for Singapore, and more importantly first found in the 0.86 km²Bukit Brown cemetery - an area that had sparked off some controversy when the Land Transport Authority announced plans to construct a new road across the site.

Why is it that after all these years, this species eluded all the butterfly watchers in Singapore? Did it just recently appear, or was it hiding in the Bukit Brown area, just waiting for someone to discover it? We cannot say for sure. We only hope that with the adjusted alignment of the proposed road at Bukit Brown, this species will still continue to survive at its current habitat, and perhaps other parts of Singapore.

Text by Khew SK : Photos by Federick Ho, Lemon Tea & Horace Tan

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, 1st Edition, 2006.