A moth with the longest tongue in the insect world – which is named after celebrated Usk-born naturalist Alfred Russel Wallace – has been declared a species in its own right, 98 years after its discovery.

Wallace, who jointly conceived the theory of evolution with Charles Darwin, predicted the existence of Wallace’s sphinx moth in the 1860s after discovering the Madagascan orchid, a plant that would need an insect with an extremely long tongue to reach the nectar in the plant’s tubes.

The naturalist – who was born in Kensington Cottage in Llanbadoc nearly 200 years ago (January 8, 1823) – said it would be similar to a hawkmoth found in Africa.

And he wrote in 1867: “That such a moth exists in Madagascar may be safely predicted, and naturalists who visit that island should search for it with as much confidence as astronomers searched for the planet Neptune – and they will be equally successful.”

Darwin, who went on to write The Origin of Species after the duo jointly co-authored a paper unveiling the theory of evolution, predicted the same.

But it took until 1903 for their theory to be proved right when the moth that pollinated the orchids was finally discovered.

With a tongue measuring up to an incredible 30cm long, scientists originally categorised it as a subspecies of Morgan’s sphinx moth.

However, almost a century on, a research team has now found through examining its physical and genetic differences that the Madagascan moth is in fact a species in its own right, which they gave the Latin name ‘Xanthopan praedicta’ in honour of the fact that Wallace and Darwin both predicted its existence.

The team found 25 morphological differences (how its body looks) between the Wallace and Morgan moths, including significant differences in shape of male and female genitalia, wing shape and colour patterns.

Dr David Lees, a curator of moths at the Natural History Museum, who co-authored the paper published in the journal Antenor, said: “Imagine my excitement as I unrolled and measured the proboscis of a male Xanthopan in the Madagascan rainforest, realising that it was probably the global record holder.

“The taxonomic change we now propose finally gives long-deserved recognition, at the species level, to one of the most celebrated of all Malagasy endemics.”

The tongue of the moth, which is only found in Madagascar, increased in length in step with the long nectar tube of the orchid until, eventually, the orchid became wholly reliant on the pollination services of the moths.

To reduce the risk of being eaten by predators, the moth unrolls its unwieldy proboscis only when they approach the flower and as soon as it finishes it rolls it back up.

While Wallace’s role in changing the history of scientific understanding was overshadowed by Darwin’s fame in the 20th century, that is beginning to change, after a campaign launched in 2013 on the centenary of his death led to the reinstatement of a giant oil painting of him at the Natural History Museum, near Darwin’s statue, and the creation of a bronze statue.

The painting was unveiled by comedian, naturalist and Strictly winner Bill Bailey, who also hosted a BBC TV series on the naturalist, whose magnum opus The World of Life was republished last summer.

Last year, scientists also rediscovered the world’s biggest bee named after Wallace, a tireless explorer who frequently travelled to the far-flung corners of the world to collect samples.

He first collected the giant insect with massive jaws and a two-and-a-half inch wingspan in 1859, but it hadn’t been seen since 1981 and was feared extinct.

That is until a team of scientists following in his footsteps found a female specimen of Wallace’s Giant Bee on a remote Indonesian island.

For more information about Alfred Russel Wallace, go to wallacefund.info