New velvet worm species a first for the arid Karoo

In March 2022, Stellenbosch University (SU) student Rohan Barnard was out and about on a farm in the Swartberg Mountains between Calitzdorp and Oudtshoorn, flipping over rocks looking for ants, reptiles and other critters, when he stumbled upon the finding of a lifetime.

Buried deep in the moist sand below a pile of leaf litter at the periphery of a small river, he found a slate black velvet worm. Being familiar with how rare velvet worms are, he took a specimen and also posted an image of it to the biodiversity observation app, iNaturalist.

“I had a basic knowledge of the Cape velvet worms, having found one for the first time on Table Mountain in 2019. My older brother was under assignment from his zoology lecturer, Prof. Savel Daniels, to collect velvet worms. With my interest in ants, I gladly assisted him in this task,” Rohan, now a third year BSc student in Conservation Ecology and Entomology, explains.

Velvet worms’ lineage date back to over 500 million years ago, making it a living relic of the Cambrian period. With their soft bodies and non-jointed legs, these critters have changed little over millions of years, earning them the title of “living fossils”.

Little did Rohan know at the time that he had just found a new species of velvet worm, now aptly named Rohan’s velvet worm or, in scientific terms, Peripatopsis barnardi.

Even more remarkable is the fact that it represents the first ever species from the little Karoo, which indicates that the area was historically more forested than at present. In other words, with prehistorical climate changes, and aridification, the species became isolated and underwent speciation.

According to Prof. Daniels, an evolutionary biologist from SU’s Department of Botany and Zoology and one of South Africa’s foremost specialists on velvet worms, it is utterly remarkable that such a prehistorical lineage is still around today. After viewing this rare find on iNaturalist, he visited the same area in July 2022 and collected a paratype and another nine specimens for analysis.

The results of his analysis, and the announcement of seven new species of velvet worms, were published in the journal Ecology and Evolution recently. Daniels, the first author on the paper, says South Africa’s velvet worms are mainly found in prehistoric Afro temperate forest patches that persist in deep gorges in the Cape Fold Mountains

“The origin of these forest patches can be traced to the early Miocene, about 23 to 15 million years ago, when the region used to be temperate and sub-tropical. During the late Miocene, however, the region underwent significant climatic changes, with a decrease in rainfall due to the advent of the proto Benguela current along the West Coast, and two geotectonic uplifting events. These events resulted in a complex mosaic of habitat connectivity and isolation, what we know today as the Cape Fold Mountains, driving the speciation of habitat specialists such as velvet worms,” he explains.

Daniels used new mitochondrial and nuclear DNA sequencing techniques, combined with morphological analysis and scanning electron microscopy (SEM), to determine that P. barnardi diverged from its most recent common ancestor about 15.2 million years ago. Another novel finding from the Cederberg Mountains, P. cederbergiensis, can trace its lineage to 12.47 million years ago.

Daniels welcomes the efforts of citizen scientists to share their findings on biodiversity apps: “It is thanks to citizen science data that we were able to identify the new species. In the Cape Fold Mountains, we now know that every mountain peak has an endemic species. This suggests that in unsampled areas there are likely to be additional novel diversity, waiting to be found.”

Most importantly, though, it means that we must conserve these prehistoric forest fragments to limit extinction.

To Rohan, it still feels surreal to have such a fossil-like creature named after him: “It is incredible to realise that I’ve uncovered a living fossil. It is as if I have found a missing link that we did not even know about. It gives me hope that there is still so much left to discover. But it also makes me worried for the future, that we will lose animals and plants to extinction that we did not even know existed,” he warns.

The seven new species are P. fernkloofi, P. jonkershoeki, P. kogelbergi, P. landroskoppie, P. limietbergi and P. palmeri. Apart from P. barnardi, all the new species were named after their places of origin.

Why are velvet worms so unique?

Like the indestructible water bears (Tardigrades), modern velvet worms are looked on as a separate line of evolution (and placed in a distinct phylum) that arose independently from some long forgotten marine ancestor – probably the Hallicogenia. Fossils show that velvet worms have not changed much since they diverged from their ancient relative about 540 million years ago. This means Onycophorans have been living on Earth ever since what is called the Cambrian period of prehistory. Today, modern velvet worms live on land and are found only in damp, moist habitats in areas that were originally part of the ancient supercontinent Gondwana.