Scorpion (Pandinus dictator)
Listed on Appendix II of CITES (1).
One of the world’s largest scorpions, thought to reach up to 17 to 20 centimetres in length (2) (3), Pandinus dictator and other species in the genus are popular in the pet trade (2) (4). Like other members of this group, Pandinus dictator possesses very powerful, broad pincers, short, robust legs with short and spine-like setae (hairs), a stout body and a thickened tail, all adaptations for a burrowing lifestyle (5) (6). Generally dark in colour, Pandinus dictator is not easy to tell apart from other Pandinus species; identification is usually based on the pattern of sensitive hairs, known as trichobothria, on the pincers, which varies between species (2). Like all scorpions, the body of Pandinus dictator fluoresces under ultraviolet light (7).
Pandinus dictator appears to have a rather restricted range in West Africa, including Cameroon, Congo, Equatorial Guinea, and Gabon (2) (5).
Pandinus dictator can be found in lowland and montane rainforest at elevations of 110 to 640 metres, constructing burrows in termite mounds and under stones or logs (5).
Like most scorpions, Pandinus dictator is primarily nocturnal (7), and like other burrowing scorpions it spends most of its life in the burrow it has excavated, leaving only for courtship, mating, for burrow maintenance or to pounce on prey from the burrow entrance (6). While most scorpion species are solitary, it is thought that Pandinus dictator may show some social behaviour, with burrows sometimes occupied by more than one individual (3).
As part of a complex mating dance, the male scorpion attaches a spermatophore to the ground while grasping the female by the pincers or the chelicerae. The male then manoeuvres the female over the spermatophore, so that the female can receive the sperm (7) (8). Unusually among arthropods, young scorpions take a long time to develop and litter sizes are relatively small. Uniquely, scorpions are also viviparous, giving birth to live young rather than laying eggs. At birth, the young climb onto the female’s back and remain there until the first moult; this maternal care may help protect the vulnerable young from predation, harsh environmental conditions or from drying out until the cuticle becomes fully waterproof (7) (8). Although little information is available on the lifespan of Pandinus dictator, it is likely that, like other scorpions, it is relatively long-lived (8).
Prey is detected using specialised slit sense organs on the legs, sensory hairs (trichobothria) on the pincers, or special comb-like sensory organs on the underside of the abdomen, known as pectines (7). As with other scorpions that possess large, strong pincers, this species is likely to use its pincers to kill and manipulate prey and to reserve its sting for larger prey or for use in self-defence (7). The venom of Pandinus dictator is not known to be dangerous to healthy adult humans.
Large scorpions such as Pandinus dictator are popular in the pet trade, and although this species is thought to be much rarer in the trade than the closely related Pandinus imperator (3) (4), this is difficult to monitor due to the difficulty for non-experts in distinguishing the different Pandinus species (4). It is not known whether destruction of its rainforest habitat is currently affecting Pandinus dictator, though the relatively small litter sizes and long generation times typical of scorpions may mean populations take a long time to recover from any losses (7).
Pandinus dictator was added to Appendix II of the Convention on International Trade in Endangered Species (CITES), meaning trade in the species should be carefully monitored and controlled, due to concerns over the level of international trade and the potential effects on Pandinus dictator populations. However, those responsible for monitoring traffic in these species are rarely scorpion experts, making identification of the different species a problem (2). There is also a lack of research into Pandinus dictator (2), meaning little is currently known about its biology and wild populations.
As a major group of predatory arthropods, scorpions are generally considered valuable indicators of the health of ecosystems and their disappearance often signals habitat degradation. However, few scorpion species receive formal protection and many are at risk of being lost before they have even been properly studied (7). It is likely that further research into Pandinus dictator will be needed before any necessary conservation steps can be implemented.
For further information on scorpions, see:
The Scorpion Files:
Scorpion Systematics Research Group, American Museum of Natural History:
Authenticated (19/03/09) by Dr Lorenzo Prendini, Associate Curator (Arachnids and Myriapods) and Head of Scorpion Systematics Research Group, American Museum of Natural History.
- Arthropods: a very diverse phylum (a major grouping of animals) that includes crustaceans, insects and arachnids. All arthropods have paired jointed limbs and a hard external skeleton (exoskeleton).
- Chelicerae: pair of appendages on the ‘head’ of an arachnid (spiders, scorpions, mites, harvestmen etc). In scorpions, these are claw-like and used in feeding (not to be confused with the larger pedipalps, or ‘pincers’).
- Cuticle: the outer, chitinous layer of the exoskeleton of an arthropod.
- Genus: a category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.
- Montane rainforest: rainforest occurring in the montane zone, a zone of cool upland slopes below the tree line dominated by large evergreen trees.
- Moult: in insects, referring to stages of growth, whereby the hard outer layer of the body (the exoskeleton) is shed and the body becomes larger.
- Nocturnal: active at night.
- Spermatophore: gelatinous jelly cone with a sperm cap deposited by a male during courtship and picked up by the reproductive tract of the female.
CITES (November, 2008)
- Lourenço, W.R. and Cloudsley-Thompson, J.L. (1996) Recognition and distribution of the scorpions of the genus Pandinus Thorell, 1876 accorded protection by the Washington Convention. Biogeographica, 72(3): 133 - 143.
- Prendini, L., Crowe, T.M. and Wheeler, W.C. (2003) Systematics and biogeography of the family Scorpionidae (Chelicerata: Scorpiones), with a discussion on phylogenetic methods. Invertebrate Systematics, 17: 185 - 259.
The Scorpion Files (November, 2008)
- Prendini, L. (2004) On the scorpions of Gabon and neighbouring countries, with a reassessment of the synonyms attributed to Babycurus buettneri Karsch and a redescription of Babycurus melanicus Kovařík. California Academy of Sciences Memoir, 28: 235 - 267.
- Punzo, F. (2000) Desert Arthropods: Life History Variations. Springer, Heidelberg, Germany.
Scorpion Systematics Research Group, American Museum of Natural History (November, 2008)
- Polis, G.A. and Sissom, W.D. (1990) Life History. In: Polis, G.A. (Ed) The Biology of Scorpions. Stanford University Press, Palo Alto.