Distribution

Sub-Saharan Africa (distribution in West and Central Africa unclear). Southwest Arabian Peninsula (along the Red Sea, from Jeddah to Yemen).

Distribution of dangerous species:

1. Southern Namibia, South Africa
2. South Africa (not in the east), western Botswana, Namibia and southwest Angola
3. Southwest Arabian Peninsula (along the Red Sea, from Jeddah to Yemen); Egypt (?), Ethiopia, Sudan, Somalia, Kenya, Tanzania
4. Northern South Africa, eastern Botswana, southern Zimbabwe and southern Mozambique
5. Northeast South Africa, eastern Botswana, southern Zimbabwe and southern Mozambique
6. Southern Zimbabwe/Mozambique and bordering regions of South Africa

Biology

Pincers relatively slender, conspicuously thick tail. The potentially dangerous specimens are found among the larger species of this genus: P. mossambicensis up to 8 cm (colouring yellowish), P. truculentus up to 9 cm (yellowish), P. liosoma up to 12 cm (light brown to reddish-brown). With a length of up to 15 cm, P. transvaalicus is one of the largest Buthidae of all (colouring dark-brown or greenish-black).

In southern Africa Parabuthus is only found in those areas that receive on average less than 600 mm rainfall per year. As the minimum rainfall required for intensive agriculture is at least 600 mm per year, the population density in the distribution areas of Parabuthus is very low.

P. mossambicensis and P. truculentus are burrowing species that dig tunnel-like burrows in sandy soil. P. transvaalicus does not burrow and can be found under fallen tree trunks or stones and debris. It also enters human habitations, as does P. granulatus. Several of the larger species possess an ability unique among scorpions, in that they can spray venom up to a distance of one metre.

An identification key for 20 southern African Parabuthus species can be found in Prendini (2004).

Parabuthus transvaalicus can adjust the quantities of venom they deliver with a sting according to the level of threat (Nisani & Hayes, 2011) . Under low threat conditions they tend to inject no venom (dry stings) or significantly lower quantities than under high threat or persistant threat conditions. Addittionally they seem to have the possibility to inject a less toxic "prevenom" or a more potent protein rich and toxic venom depending on the persistance of threat. The control of quantity and quality of venom injection seems to help to save the high costs in venom production.

Risk

Although Parabuthus venoms demonstrate lower toxicity than the venoms of dangerous northern African Buthidae, stings can be dangerous to humans due to the large quantities of venom they possess. The large P. transvaalicus can deliver up to 14 mg (dry weight) of venom, while generally only less than 1 mg (dry weight) of venom can be obtained in the laboratory from the northern African Buthidae (Newlands and Martindale 1980).

Until recently only isolated cases – albeit cases of systemic envenoming – were known from the literature:

• P. liosoma in Saudi Arabia (Goyffon and Vachon 1979);
• Parabuthus sp. (probably P. transvaalicus) in Zimbabwe (Saunders and Morar 1990);
• P. granulosus in Botswana (Petersen 1987);
• Parabuthus sp. in South Africa (Smith et al. 1983).
• One publication presented for the first time a series of cases of scorpion envenoming from southern Africa (Müller 1993). This study describes 42 serious cases, 4 of which were fatal, from western Cape Province. Of the 15 scorpions that were available for identification, 14 were P. granulosus and the other was probably P. capensis.
• Bergmann (1997) published a study of P. transvaalicus stings from Zimbabwe. 10% of the stings were associated with a severe course of envenoming, with a mortality rate of 0.3%. Fatal envenoming was observed in children under 10 years and adults over 50 years.  

In addition, Newlands and Martindale (1980) suggest that P. mossambicensis and P. truculentus might also be "potentially lethal" species.

There is one case of an incident in which venom was sprayed into the victims' eyes, but there are no details regarding the effects of the venom (Newlands 1974).

Literature (biological)

Belfield 1956, Fet et al. 2000, Gough and Hirst 1927, Lamoral 1979, Müller 1993, Prendini 2004, Probst 1973, Newlands 1974, 1978, Newlands and Martindale 1980, Vachon 1979

The Scorpion Files

The Scorpion Fauna