a wingspan of 194 mm, the female of the species is marginally larger than the Southern Birdwing (190 mm) that Brigadier William Harry Evans, a British military officer and lepidopterist, had recorded in 1932. But the male Golden Birdwing (Troides aeacus) is much smaller at 106 mm.
The new measurements of this and 24 other species of butterflies were published in the latest issue of Bionotes, a quarterly newsletter for research on life forms. Shristee Panthee of the University of Chinese Academy of Sciences in Yunnan and Peter Smetacek of the Butterfly Research Centre at Bhimtal in Uttarakhand are the authors of the study.
Brigadier Evans’ record “The hitherto largest Indian butterfly that Brigadier Evans recorded in 1932 was an individual of the Southern Birdwing (Troides minos), which was then treated as a subspecies of the Common Birdwing,” Mr. Smetacek told The Hindu on July 7.
“But the specimen he measured was unknown, and no other butterfly measured as much as the 190 mm that he recorded,” he added.
While the female Golden Birdwing was recorded from Didihat in Uttarakhand, the largest male was from the Wankhar Butterfly Museum in Meghalaya capital Shillong.
According to the authors, the only measurement used in the study of Lepidoptera is wingspan — a simple concept with various interpretations of the term.
“Some older authors measured a straight line between the forewing apices (pointed ends or tips) of pinned specimens. This was controversial, since the same butterfly could have different wingspans, depending on the position of its forewings in relation to each other,” the study says.
More reliable method Brigadier Evans followed a more reliable method. He measured a butterfly from the centre of the thorax to the tip of the forewing apex and doubled the result. He provided wingspans of all butterfly species then known from the Indian subcontinent and his book is still the standard work on the subject.
The updated wingspan of three species — all from Uttarakhand — after the Golden Birdwing are Common Windmill (Byasa polyeuctes) at 98 mm, Great Windmill (Byasa dasarada) at 96 mm, and Common Peacock (Papilio bianor) at 78 mm.
The smallest is the Quaker (Neopithecops zalmora) with a wingspan of 18 mm and forewing length of 8 mm. The largest female Golden Birdwing’s forewing length is 90 mm.
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