Niue's Only Endemic Butterfly Discovered by Museum Researcher

Gold Coast school teacher Rob Lachlan has been collecting butterflies and moths for over 50 years throughout Papua New Guinea and most Pacific island nations, and now has a private collection of over 30,000 specimens. He's spent numerous school holidays engaged in his passion, travelling to many parts of the world researching butterflies and hawk moths.

On a recent trip to a Pacific Island he discovered a species that somehow everyone else had missed...

What exactly have you discovered, Rob?

I found a small blue butterfly on the island nation of Niue in the south-western Pacific Ocean: Niue Blue Nacaduba niueensis. This was extremely surprising as the Pacific Islands have, generally speaking, been thoroughly researched by numerous scientists and expeditions over many decades. As such it is widely accepted that the chances of finding any new butterfly species amongst any of the Pacific islands is now very remote indeed. It is an endemic species only found on Niue, a single island nation. The nearest island is hundreds of kilometres away, so it is very isolated.

How did you find this rare species?

On a two week trip to Niue in December, 2009 I caught a single male, small, blue butterfly from a flowering tree and was not quite sure what it was. On returning to Australia I discovered it was an undescribed species. I learnt, after reading up on a variety of published scientific papers on the Pacific, a very similar single female butterfly had been collected 30 years earlier. Two specimens in thirty years suggests that the species is possibly very rare.

And what's been the response so far?

The response to its discovery has been one of considerable surprise with everyone wondering how it could have been missed. John Tennent, an expert entomologist on Pacific island butterfies from the Natural History Museum, London, expressed the same feelings.

Because there are only a handful of plant and animal species which are unique to Niue this butterfly has particular importance to the people of the island. The Premier of Niue intends to make this species the national butterfly for the island, and to feature this insect on a special run of postal stamps.

And what about you, how do you feel about it all?

Naturally I was very surprised but also quietly thrilled to come across such an unexpected find on a small, very remote island with very few butterfly species recorded there so far.

What's your approach to collecting? How is it done?

I've been collecting for many years on numerous Pacific islands hoping to find new species but always realising the chances are very low. The material is collected using large butterfly nets. Several hours are spent each day just wandering around forest trails or along roadsides with flowering plants.

I have discovered many new species of butterflies and hawk moths over the years and published numerous scientific papers. I was elected a Fellow of the Royal Entomological Society of London in 1984 and, more importantly to me, have been a Research Associate of the Australian Museum’s Entomology Department since the 1980s.

What's next on your collecting agenda?

I'd like to return to Niue one more time to see if I can find the species in other areas of the island.

The Australian Museum is honoured to act as custodians for the type specimens of this rare butterfly on behalf of the people of Niue. 

The Niue Blue is the only endemic butterfly species found on the remote Pacific island of Niue. It was described by Australian Museum Research Associate in 2012 from a pair of specimens, a male captured by Rob, and a female from the collections in the Bishop Museum, Hawaii.