Parabuthus  (burrowing thick-tailed scorpions)

Life > Eukaryotes > Opisthokonta > Metazoa (animals) > Bilateria > Ecdysozoa > Panarthropoda > Tritocerebra > Arthropoda > Arachnomorpha > Cheliceriformes > Chelicerata > Euchelicerata > Arachnida > Scorpiones (scorpions) > Superfamily: Buthoidea > Family: Buthidae 

Parabuthus is an Afrotropical genus with 20 of the 28 species endemic to southern Africa. It occurs in areas of less than 600 mm of rain per annum and is absent in southern Africa from the extreme Eastern Cape, Kwazulu Natal, much of the Free State and the Highveld. The distribution extends northwards through eastern Africa to the Arabian Peninsula. Parabuthus avoids moist or humid conditions and is thus absent from tropical central and the western bulge of Africa.

It is a psammophilous scorpion adapted to areas of soft to hard gritty soil. They all dig shallow burrows in sand at the base of shrubs, under rock, logs or any suitable cover. The females are normally sedentary, staying at home, while males of certain species are lapidocolous, using any available cover during its wanderings or may even excavate a new burrow.

Parabuthus range in size from 40 to 140 mm long, usually longer than 70 mm. Parabuthus schlechteri, traansvaalicus and villosus are the largest buthids in the world, measuring up to 140 mm. The colour ranges from a yellow through brown to black without any of the characteristic markings found on other buthid scorpions. The legs are usually lighter in colour than the body. Most species have a very robust tail with the first 2 tail segments having nodes or ridges across which the aculeus (sting) is scraped producing a stridulatory, warning hiss. Some species stridulate more readily than others do. Parabuthus is also the only buthid scorpion in southern Africa to stridulate in this way.

Parabuthus scorpions are of great medical importance and all species must be regarded as potentially lethal. In the north-western Cape scorpions are more of a problem than snakebite with the reverse being the case in Kwazulu/Natal.

The quick acting venom negates the need for large chelae which are only used to hold onto its prey while being stung and unlike the thin-tailed scorpions, the chelae are not used to kill or hold onto its prey while succumbing to the weak venom. Whether there is any logical connection between chela size and tail thickness is still debatable as Parabuthus also uses the thick tail for burrowing. The tail with stinger is held over the head ready to strike but Parabuthus can also execute a sideways defensive jab – so do not try and pick it up with the fingers!

Gerry Newlands was the first to mention that certain Buthidae scorpions spray venom up to 1 metre and the fifth metosomal (tail) segments of these scorpions are enlarged. The 3 species cited are Parabuthus schlechteri, P. transvaalicus and P. villosus. This has not yet  been documented conclusively and is refuted by some experts – so lets get it on video!

Some of the species in southern Africa

Parabuthus granulatus (Granulated thick-tailed scorpion) The Granulated thick-tailed scorpion is large, about 115 mm in length and dark yellow to brown colour. It has a relatively small vesicle compared to other species. It is common from just north of Cape Town to northern Namibia and eastwards into the Northern Province. This scorpion is responsible for most of the serious cases of envenomation in South Africa. The venom is more toxic than Parabuthus transvaalicus.
Parabuthus stridulus P. stridulus occurs in the Namid dunes from Oranjemund in the south to the Ugab River in the north. This scorpion has a shiny integument.
Parabuthus planicauda This scorpion is commonly found under stones in the Boland, south coast and Karoo and is often misidentified as P. capensis.
Parabuthus capensis (Cape thick-tailed scorpion) 70 to 100 mm in length and a yellowish-brown colour although a black variety also occurs. It occurs just north of the Cape Peninsula northwards into southern Namibia and extending eastwards into the Eastern Cape becoming less common with this eastward distribution.
Parabuthus transvaalicus (Transvaal thick-tailed scorpion) The Transvaal thick-tailed scorpion is large, about 140 mm in length and dark brown to black and hairy. It is reputed to be the second most venomous southern African scorpion. This scorpion can also be active in the morning and can be found in thatched roofs.
Parabuthus mossambicensis This scorpion is very common in the far Northern Province and southern Zimbabwe and looks similar to P. transvaalicus.
Parabuthus villosus (Black hairy thick-tailed scorpion) The Black hairy thick-tailed scorpion is large, about 140 mm in length and is black in colour. It is often seen during the day and is common from the Northern Cape and Namibia. Besides its normal prey it also captures lizards and mice.

Text by Norman Larsen ©.