Francis’s gorgeous sapphire — a new-to-science species of butterfly — has just been described in the high-altitude evergreen forests of western Angola. The identification of Iolaus francisi, with its shimmering blue upper wings bordered with black, and silvery underwings patterned with orange and brown lines highlights once more the rich biodiversity of the country’s most threatened habitat.

Ecologist Alan Gardiner recalls the exciting moment he and Zimbabwean lepidopterists (butterfly experts) Jonathan Francis and Shabani Ndarama first saw a male sapphire shining in a forest patch during an expedition to the Namba Mountains in Cuanza Sul province in May 2023.

“It’s always special when you see something like that,” says Gardiner, head of applied research at the South African Wildlife College. “It’s so much more vivid than you can get in a picture.”

Described recently in the journal Zootaxa, Francis’s gorgeous sapphire is now one of 13 unique butterflies known only from this region. Its caterpillars feed on the leaves of Phragmanthera mistletoes and mimic the hairy buds growing on the stems.

Francis had collected two caterpillars of the butterfly in the Namba Mountains during an earlier trip in October 2022.

He reared them back home in Zimbabwe, feeding them on the leaves of mistletoe plants he had cultivated in his Harare garden years earlier. “If I didn’t have the [mistletoe] leaves, I would have lost them.”

The butterflies that emerged were both females, with distinctive undersides bearing an extra stripe that no other Iolaus butterflies have, he says. But without a male, the team could not yet confirm it as a new species.

The following May they returned to Namba.

“They’re [living] very high up in these hectic, boulder-strewn forests — a lot of precipices and things like that,” Francis says. “It’s not easy [to catch them] at all.”

But they did catch a male and collected two more caterpillars — this time a male and a female. “Once we had the male we could do the genitalia [examination] and that kind of clinched it as a [new] species,” Francis says.

Mistletoes, and therefore the butterflies themselves, are highly vulnerable to fire, which some experts say are becoming more frequent in Namba and penetrating deeper into closed-canopy forest.

“Fire kills mistletoe plants, even if their host trees survive,” Gardiner says.

The loss of mistletoe would ripple through the web of species that depend on it. When sunbirds prod the plants’ yellow flowers for nectar, they explode in their faces, coating them with pollen that they take to other flowers. Fruit eaters, like western tinkerbirds (Pogoniulus coryphaeus), later spread the mistletoe’s sticky seeds by wiping them off their beaks onto tree branches.

“That’s why you want to protect the whole system,” Gardiner says, “because nothing’s in isolation.”

Namba’s Afromontane forest patches, covering only around 590 hectares (1,460 acres), are the largest remnants of this ecosystem in Angola, but remain vulnerable not only to fire, but to agriculture, firewood collection and timber harvesting.

“There’s undoubtedly stuff [yet to be found and described in Namba],” Gardiner adds. “Whether we find it in time or not is the question.”

Namba’s forests, and those on nearby Mount Moco, Angola’s highest mountain, are thought to be relics of past glacial ages; as a result, they host plants and animals isolated for millennia from similar ecosystems elsewhere in Africa. This has fueled high rates of speciation and created the opportunities for new discoveries.

A separate 2022 expedition by a group of scientists discovered up to 10 probable new species in Namba’s forests, including toads, dragonflies, bats and rodents. Among its unique birdlife are species — like the naked-faced barbet (Gymnobucco calvus vernayi), orange ground thrush (Geokichla gurneyi) and Laura’s woodland warbler (Phylloscopus laurae) — that are now rare or missing in Mount Moco’s forests.

It’s not only wildlife that benefits from an intact ecosystem in Namba. The mountains give rise to streams and rivers that sustain wetlands and farming communities in the plains below the escarpment, says Angolan conservationist and National Geographic explorer Kerllen Costa.

“There’s also a big, strong concept [among surrounding communities] of how the actual mountain range of Namba provides the lifeline for the people,” he says. “They believe that the soil sustains and allows them to survive because of the role that the mountain range plays for them.”

Costa says that community-led conservation, rooted in local ecological knowledge and cultural ties to the land, offers the best chance of safeguarding Namba’s remaining forests. Discoveries like the new butterfly also help by drawing attention to their rich biodiversity.

“It elevates the need to pay attention to these places because, clearly, they are biodiversity hotspots, they are endemism hotspots [more so] than most of the other regions in the country, and those places are crucial for the functioning of entire systems,” Costa says.

In July, the Angolan cabinet forwarded draft legislation to lawmakers that aims to establish a protected area around Mount Moco, which holds less than 85 hectares (210 acres) of remnant Afromontane patches. But the Namba Mountains, with their larger share of threatened forest, remain unprotected.

This could change. Martim Melo, a research associate at the University of Cape Town’s FitzPatrick Institute of African Ornithology who took part in the 2022 expedition that found 10 probable new species in Namba, says he and colleagues presented their findings soon afterward to the director of Angola’s National Institute of Biodiversity Conservation, urging the authorities to create a protected area with community participation.

“[The director] took note of the importance of the area and the urgency of granting official protection to these unique, but very fragile, forests,” Melo tells Mongabay. “We are now looking for funds to put together a team to carry out the extensive technical work required to guide the implementation of a future protected area in Namba.”

Costa maintains that unsustainable farming and timber harvesting are currently the biggest threats to Namba’s forests.

Once forest clearance or timber extraction begins, it escalates quickly, he says. Sometimes the farmers who clear forests on slopes along the escarpment are newcomers dismissive of traditional, sustainable farming systems, over whom village leaders have little control.

He points to Kumbira, a once-renowned Afromontane forest patch north of Namba, near the town of Gabela, which has been devastated in just the past seven years or so due to unregulated agriculture.

“Potentially that could also happen at Namba,” he warns.

Banner image: A brilliant blue male Francis’s gorgeous sapphire, euthanized after being reared in captivity. Image courtesy of Jonathan Francis.

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Citation:

Gardiner, A. J. (2025). A new Iolaus species (Lycaenidae: Theclinae) from the highlands of central Angola. Zootaxa, 5660(1), 67-79. doi:10.11646/zootaxa.5660.1.3

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