New “evolutionary relic” discovered in Cape Town

The Table Mountain National Park, already a World Heritage Site and one of the country’s most popular tourist destinations, is now also home to a new species of diving beetle that was recently discovered by scientists working in the area.

According to a paper that was recently published in the journal Systematic Entomology, this particular beetle known as the Capelatus prykei had been living in isolation in the Noordhoek Wetlands and it is so different from any other diving beetles in the world that it has been placed in its own genus.

Dr David Bilton, reader in Aquatic Biology at Plymouth University, said it was fairly common to find new species of beetle, “but it’s much less usual to find things which are so different they have to be put in their own genus. Our study of DNA sequences shows that the closest relatives of Capelatus live thousands of miles away, and that they last shared a common ancestor around 30-40 million years ago.”

The diving beetles’ nearest relations are found only in the Mediterranean and in New Guinea.

Bilton added: “This beetle’s a real evolutionary relic, which only seems to have survived in a very small area close to Cape Town, probably because this region has had a relatively stable climate over the last few million years. Today Capelatus is extremely rare though – in fact we know of only one population, fortunately located inside Table Mountain National Park. We’ve also found old, unnamed specimens in the Natural History Museum in London, but the area where these were caught in the 1950s is now under the suburbs of the city.”

Although Bilton wrote the study with Plymouth entomologist Clive Turner and colleagues from the Museum of Zoology in Munich, he said there were also South African scientists who had been involved along the way.

“This beetle was actually first turned up at Noordhoek by Dr James Pryke of Stellenbosch University, a few years ago when he was conducting his PhD research on invertebrates of wetlands on the Cape Peninsula I believe. James had asked a friend and co-author of mine, Clive Turner, to identify his beetles. Clive and I recognised that this thing was something special, which led to the study published in Systematic Entomology. So in a sense there has been collaboration with SA [South African] folks all along. After getting the material from James, we subsequently found old (1950s) material in the NHM [Natural History Museum], London, collected in an area on the Cape Flats which has since become part of the suburbs of Cape Town.”

He said that he went back to the area last year to look for this particular beetle on both sides of the False Bay coastline but got nowhere.

“Dr Matt Bird, now at NMMU [Nelson Mandela Metropolitan University], completed his PhD on wetlands in the Western Cape recently, and never found it either. It is maybe that it is genuinely restricted to that one site now.”

Bilton said that he visited the country every year to take his students to the West Coast National Park on a field course and that he also used that time to work on water beetles.

“I’ve links with folks in Stellenbosch and NMMU, and have so far discovered ca. 30 new species in the last 5 years, mostly in the Western Cape.”

The Western Cape has one of the most unique biodiversity in the world – which include plants and animals – and it is supports about 20 per cent of the plant species found in sub-Saharan Africa – most of which are restricted to the region.

Bilton and his co-authors in the study suggested that the diving beetle be provisionally listed by the International Union for Conservation of Nature (IUCN) as a critically endangered species.

He explained that: “In terms of IUCN lists, these are really down to individual specialists or groups of specialists reviewing a taxonomic group and evaluating which species should and shouldn’t be listed.

It is a really tall order to do this for all diving beetles (there are over 4,000), hence the provisional listing in the paper. We wanted to highlight that this special beetle really seems to be genuinely rare.”

He said that copies of their paper have gone to Cape Nature and the Table Mountain National Park.

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