Phylogeography of Androctonus species in Tunisia in view of their medical importance

 

The genus Androcronus Ehrenberg, 1828 hosts many medical important species in Tunisia and the rest of North Africa. Information about inter- and intraspecific variation of the Androctonus species is important, especially if this has consequences for medical importance and treatment of sting cases.

A. Ben Othmen and co-workers have recently published a study on the phylogeography and a phylogenetic analysis of Androctonus species in Tunisia. The results supported the current species Androctonus aeneas C. L. Koch, 1839, Androctonus amoreuxi (Audouin, 1839) and Androctonus australis (Linnaeus, 1758), but not the existence of subspecies of A. australis. 

The authors recommend that toxicologists should not refer to "species" or forms like "A. australis Hector", but suggest that it may be wise to produce anti-venom in Tunisia by using both morphological forms of A. australis.

Abstract:
A fragment of the mitochondrial (mt) 16S ribosomal RNA gene was amplified by PCR and sequenced from individual adult scorpions of the genus Androctonus, which were sampled from central and southern Tunisia and identified using an explicit set of morphological characters. Phylogenetic analyses placed the mtDNA haplotypes in three well-supported monophyletic lineages, corresponding to the morphospecies Androctonusaeneas, Androctonusamoreuxi and Androctonusaustralis. The latter species was the most abundant and widespread, and it was characterized by two mtDNA sub-lineages each of which predominated only north or south of the Chott el Jerid, a seasonally flooded saline depression that divides non-Mediterranean Tunisia. The divergence of the two mtDNA lineages was dated by mtDNA molecular clocks, indicating that the formation of the Chott el Jerid is unlikely to have been the barrier generating the vicariant evolution of the two lineages of A. australis, although it may have impeded their mixing following secondary contact. Both regional mtDNA lineages were found in A. australis hector and A. australisgarzonii, indicating that these two morphological forms are neither monophyletic nor geographically isolated and, therefore, should not be treated as species or subspecies. It is recommended that no subspecies of A. australis should be recognized in North Africa and toxicologists should cease the taxonomic error of referring to a species “Androctonus australis Hector”. The morphological form “hector” has no proven association with an increased risk of scorpionism compared with “garzonii”. However, it might be prudent to produce anti-venom in Tunisia by using both morphological forms of A. australis collected each side of the Chott el Jerid, because of the evidence for regional variation in toxins. The highest risk for scorpion stings occurs in the central region, where the new diagnostic markers should be used to discover any association between Androctonus species and scorpionism.

Reference:
Ben Othmen A, Said K, Mahamdallie SS, Testa JM, Haouas Z, Chatti N, et al. Phylogeography of Androctonus species (Scorpiones: Buthidae) in Tunisia: Diagnostic characters for linking species to scorpionism. Acta Trop. 2009;112(1):77-85. [Subscription required for full text]

Family Buthidae