Colombia's twice-forgotten yellow butterfly offers hope for tropical wildlife

The Catasticta lycurgus is restricted to high elevations of an isolated mountain range, the Sierra Nevada de Santa in northern Colombia.

It was first discovered by British civil engineer and geographer Frederick Simons during one of his many explorations of the country in 1878.

Frederick captured the specimen along with many other butterflies and sent them to renowned naturalists Frederick Godman and Osbert Salvin in Britain. There, the butterfly was described as a new species, donated to the Museum and soon forgotten.

Museum entomologist Dr Blanca Huertas says, 'For almost a century, this holotype was the only known sample of the butterfly Catasticta lycurgus. My colleagues and I studied the Adams and Bernard collections in the Museum and saw that while the butterfly was not lost, it was not highlighted either. And we thought it deserved to be.'

Rediscovering the elusive Catasticta lycurgus for the first time

Almost a century later, a bright yellow butterfly was captured in the same location.

English explorers Mike Adams and George Bernard visited the Sierra Nevada de Santa in Colombia in 1971, followed by a bigger expedition in 1972.

Climbing the mountain range was no easy feat. Peaking at an impressive 5,730 metres (18,800 feet), it is one of the tallest coastal ranges in the world.

The thin air and rough, steep terrain required outdoor experience and specialist equipment to navigate. But Mike and George overcame the challenges and were rewarded with the discovery of many new species, making the expedition an important event in history.

At an elevation of 2,900 metres, the explorers spied various butterflies fluttering around a cube-shaped bush. They captured the specimens and later found one of them to be a Catasticta lycurgus, the second ever to be collected.

However, no further samples were collected due to the difficulty of reaching the location. Catasticta lycurgus was, once again, quietly forgotten. Some even believed it to be extinct - until recently.

Curiosity gleans new information on the yellow butterfly

On the other side of the world, Blanca and colleagues had just wrapped up researching endemic fauna in Singapore.

The study, which involved comparing the first and most recent butterfly specimens collected, unearthed something shocking: more than half of Singapore's endemic fauna had gone extinct in the last century, prompting a range of conservation work to be done.

Blanca wanted to do the same for the country she had been born in, but this would be a much bigger challenge. While there are only around 400 butterfly species in Singapore, there are almost 4,000 in Colombia.

'I wanted to focus my efforts on tropical areas because they contain most of the world's biodiversity,' explains Blanca. 'Ironically, we know less about the fauna there, mostly due to a lack of resources and difficult-to-reach location.'

A group of Colombian entomologists carried out some expeditions to the Sierra Nevada de Santa in 2013 and 2016. To their delight, they found many Catasticta lycurgus and collected 15 males and one female - the latter being the first ever found.

Using the newly found specimens and combing through archival materials, Blanca and collaborators published a paper titled 'One Hundred Years of Solitude: rediscovery of Catasticta lycurgus (Godman & Salvin, 1880), a yellow butterfly from the Sierra Nevada de Santa Marta, Colombia'.

The research, which received seed funding from the Department for Business, Innovation and Skills through the Rutherford Fund, established a detailed description of the twice-forgotten charismatic butterfly. It also shed light on new information such as the butterfly's exact location, its restricted distribution and its relationship with close relatives - all of which are needed for conservation work. Blanca and colleagues have already drawn up a preliminary conservation assessment.

'Finding the yellow butterfly in the field recently has given us hope that it is not extinct,' says Blanca. 'The research has established a baseline for future studies. People can start monitoring and doing more targeted conservation work in these rare habitats, which will also indirectly benefit other less charismatic or unknown species.'

Despite the additional 16 butterfly specimens, Catasticta lycurgus remains rare in the field and in collections. Scientists have yet to learn what the species looks like as an egg and as a caterpillar, as well as what it eats during the various stages in its life.

'It's really important that we find out what this species eats,' says Blanca. 'Caterpillars feed on specific plants and the reoccurrence of the butterfly depends strongly on the host plant. If the plants aren't there, you won't find the butterflies. This indicates that something has changed. This is also the reason why butterflies are considered a bioindicator.'

The Sierra Nevada de Santa is home to thousands of unique species which have evolved with each other, creating an intricate network of ecosystems. The yellow butterfly is an important species to recognise and highlight because it can help scientists understand the evolution that has taken place there.

Many of the species that live in the Sierra Nevada de Santa are also threatened. In 1979, the mountain range was listed as a UNESCO Biosphere Reserve, and, more recently, as one of the Key Biodiversity Areas for Conservation (KBA) and an Alliance for Zero Extinction Site. However, the area is still affected by farming, logging and localised fires, and it requires more focused research.

'This small case highlights that sometimes we have unique things in collections that we think might no longer exist but does,' says Blanca. 'It shows we need more people actively working in museum collections. I plan on doing this with the other specimens collected in the Adams and Bernard expeditions to those remote areas, many of which are no longer forests.

'The yellow butterfly is just the start.'