Scientific Services

South Africa has two genera of velvet worms – Peripatopsis occurring mainly in the Cape and Opisthopatus, occurring in the north-east of the country. They are nocturnal predators, ambushing other invertebrates with sticky slime squirted from a pair of specialised glands on their heads.

A recent study of Cape velvet worms by Stellenbosch University researchers Aaron Barnes, Savel Daniels and Till Reiss discovered new species in the Garden Route’s indigenous forests! The formerly known Knysna velvet worm, Peripatopsis clavigera, actually comprises five different species that separated during the Plio–Pleistocene over 5 million years ago. Their existence is testimony to the health and diversity of our indigenous forests.

Most velvet worm species give birth to live young (most females have a placenta), have been observed caring for their young and some even have a social structure led by matriarchs, like elephants, who leave a scent for families to follow their whereabouts. Historically, species were differentiated using only morphology (i.e. what they look like, including leg counts) but species often look very similar. Therefore, the researchers used DNA analyses to confirm species classifications and better understand their evolutionary relationships and the effects of major historic climatic changes in the region.

Velvet worm movement is highly restricted, and they only occur in pristine habitats, generally in damp decaying logs within Afrotemperate forests. Based on previous findings, the researchers expected to find three species at most within geographically isolated areas. Instead, velvet worm species were found to be randomly distributed across forest patches, sometimes with several species in the same log, an unexpected finding.

The Afrotemperate Southern Cape forests were found to be shaped by climatic conditions, characterised by alternate wet and dry periods which impacted on the distribution of both forests and subsequently velvet worms. Associated forest contraction and expansion events would have either hindered or assisted velvet worm movement. Populations probably moved slowly from one area of the forest to the next during wet conditions but were cut off from each other during dry conditions, resulting in speciation. The many cycles of forest contraction and expansion likely shaped to the unusual distribution of velvet worm species observed in the study.

Indigenous forests of the Garden Route National Park present a unique ‘playground’ for discovering new species and understanding diverse past and present ecological processes. Studies like this highlight the importance of maintaining healthy indigenous forests and the wonders of nature they harbour, with so much more left to understand and discover. Let’s slow down, appreciate and look after these small yet ancient marvels sharing our planet.

Aaron Barnes in field with a velvet worm. Photo by Aaron Barnes.

Conservation and Red List status

The new velvet worm species have been proposed to fall within the threatened categories on the International Union for Conservation of Nature (IUCN) Red List with P. mellaria suggested as vulnerable, P. ferox as near threatened, P. edenensis as endangered and P. clavigera changing status from vulnerable to critically endangered.

Can you spot the researcher? (Photo: Aaron Barnes)

Reference

Barnes, A., Reiss, T. and Daniels, S.R., 2020. Systematics of the Peripatopsis clavigera species complex (Onychophora: Peripatopsidae) reveals cryptic cladogenic patterning, with the description of five new species. Invertebrate Systematics, 34(6), pp.569-590.