When Charles Darwin came across the long-necked Angraecum sesquipedale orchid species (also known as Darwin’s orchid) on the island of Madagascar, he had a curious thought: There must be an insect on the island with a tongue long enough to feed itself on the plant. “Good heavens,” he exclaimed, “what insect can suck it?”
Though the moth, named Xanthopan praedicta, was indeed discovered in 1903, scientists categorized it as a subspecies of its mainland counterpart, X. morganii. More than a century later, the researchers say the two moths are distinct species.
Equipped with a set of morphological and genetic tests, scientists argue that the island moth boasts different enough characteristics from X. morganii to justify its elevation to the species level, reports Science.
As part of the study, the researchers worked with a combination of wild moths and museum specimens. According to the team, DNA barcoding — a technique used to identify organisms by looking at DNA sequence differences in the same gene or genes — proves the moths have a 7.8 percent genetic difference, making the morganii moths more closely related to other mainland subspecies than praedicta.
The most striking physical difference is, of course, the tongue length. The Malagasy variant is the clear winner, with a proboscis measuring 6.6 centimeters longer on average, as seen in the image above. According to the study, the scientists have also discovered a praedicta specimen with a tongue that measured as much as 28.5 centimeters when fully stretched, making it the longest insect tongue ever recorded.