''Parabuthus'', commonly known as the thick-tailed scorpion, is a

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of large and highly venomous

Afrotropical The Afrotropical realm is one of the Earth's eight biogeographic realms. It includes Sub-Saharan Africa, the southern Arabian Peninsula, the island of Madagascar, and the islands of the western Indian Ocean. It was formerly known as the Ethiopi ...

scorpion Scorpions are predatory arachnids of the Order (biology), order Scorpiones. They have eight legs and are easily recognized by a pair of Chela (organ), grasping pincers and a narrow, segmented tail, often carried in a characteristic forward cur ...

s, that show a preference for areas of low

rainfall Rain is a form of precipitation where water droplets that have condensed from atmospheric water vapor fall under gravity. Rain is a major component of the water cycle and is responsible for depositing most of the fresh water on the Earth. ...

. Their stings are medically important and human fatalities have been recorded.Larsen, Norman. Biodiversity Explorer, IZIKO. Scorpion stings and venom

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Characteristics

They have thick and strong tails, with typically a rough surface to the first (proximal) and sometimes second segment, that is used to produce a warning sound when rubbed against the sting (save '' Parabuthus distridor, P. distridor''). Their thick tails are also employed in excavating their shallow burrows, as several are adapted to sandy environments. Some flatter-bodied species, however, take refuge in rock crevasses. Due to their stings' quick-acting venom, they rely to lesser extent on their slender pinchers (chelae) to hold onto prey. Three species, '' P. schlechteri'', '' P. transvaalicus'', and '' P. villosus'' are thought to be able to spray venom from their tails. These three are also the largest buthids in the world, reaching lengths up to 140 mm and masses up to 14 g. Other consistent features include a dorsal head covering (

carapace A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the unde ...

) that lacks

granular Granularity (also called graininess) is the degree to which a material or system is composed of distinction (philosophy), distinguishable pieces, granular material, "granules" or grain, "grains" (metaphorically). It can either refer to the exten ...

ridges (carinae), while the

tail The tail is the elongated section at the rear end of a bilaterian animal's body; in general, the term refers to a distinct, flexible appendage extending backwards from the midline of the torso. In vertebrate animals that evolution, evolved to los ...

's upper coverings ( tergites) have only one inconspicuous middle (median) ridge. The pectine teeth nearest the body in females are enlarged and dilated ('' P. granulatus'' and '' P. kalaharicus'' excepting), and the lower tarsi (third distal segment) of the front four legs are equipped with bristle combs.Also referred to as macro

seta In biology, setae (; seta ; ) are any of a number of different bristle- or hair-like structures on living organisms. Animal setae Protostomes Depending partly on their form and function, protostome setae may be called macrotrichia, chaetae, ...

l combs or "sand combs". The ventrosubmedian ridges in the fourth tail segment disappear away from the body, and the ventrolateral ridges of the fifth segment include distinctly spined or lobed processes near their distal ends.

Diversity

Most of the species, some 20 of the total of 28, are endemic to southern Africa, but they range through eastern Africa to the Arabian Peninsula.

Selected species

* '' Parabuthus brevimanus'' * '' Parabuthus capensis'' * ''

Parabuthus granulatus ''Parabuthus granulatus'', commonly known as the granulated thick-tailed scorpion, a large species of scorpion from the drier parts of southern Africa. It measures some 11.5 cm, and is dark yellow to brown in colour. It has a relatively smal ...

'' * '' Parabuthus laevipes'' * '' Parabuthus liosoma'' * '' Parabuthus mossambicensis'' * '' Parabuthus namibensis'' * '' Parabuthus raudus'' * '' Parabuthus schlechteri'' * '' Parabuthus stridulus'' * ''

Parabuthus transvaalicus ''Parabuthus transvaalicus'' (known as the Transvaalicus thick-tailed scorpion, South African thick tail, or giant deathstalker) is a species of venomous scorpion from semi-arid parts of southern Africa. Description ''Parabuthus transvaalicus'' ...

'' * '' Parabuthus villosus''

Phylogenetics

Its nearest relations are the Afrotropical buthid genera '' Grosphus'' and '' Uroplectes'', which lack the distinct stridulatory surfaces. The following

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

illustrates relationships among 20 ''Parabuthus'' and these outlying genera, according to an analysis done by Lorenzo Prendini et al. 2003. Some recently described species (''P. cimrmani'', ''P. eritreaensis'', ''P. truculentus'' and ''P. zavattarii'') were not considered in the investigation, so that their positions within this system remain unresolved.

Notes

References