Search

The twelve Arab countries of the Middle East are inhabited by 117 species of scorpions of varying medical importance within six families. Scorpion stings are a very common occurrence throughout the region. Twenty-two scorpion species are considered to be dangerously venomous, causing potentially life threatening stings. Accessible literature in English and Arabic on scorpions, scorpion stings and available antivenoms was reviewed to document the scorpion fauna and scorpion stings in each country. Saudi Arabia, Iraq and Jordan report the highest numbers of stings and envenomings. Clinically, the most important toxins in Old World scorpion venoms are α-toxins that target voltage-gated sodium (Na v) channels at neurotoxin binding site 3, causing sympathetic excitation and the endogenous release of catecholamines that is responsible for transient, but life-threatening myocardial damage. Most victims of scorpion stings suffer severe local pain, but a few, especially children, develop systemic envenoming which, in the case of most Middle Eastern buthid species, such as Androctonus and Leiurus species, is dominated by the cardiovascular and respiratory consequences of hypercatecholinaemic myocarditis. Other syndromes include paralysis (Parabuthus leiosoma), coagulopathy (Nebo hierichonticus and Hemiscorpius species), and local tissue damage, haemolysis and acute kidney injury (H. lepturus). Early antivenom treatment is recommended but its value remains controversial. However, intensive care, with the ancillary use of vasoactive drugs such as prazosin and dobutamine, has proved effective. Image 1 • The taxonomy and occurrence of medically important scorpion species in each Arab country in the Middle East is reviewed. • Epidemiology and clinical features of envenoming by dangerous species are described. • Based on current practice, use of antivenoms and ancillary treatments in Arab countries in the Middle East is discussed. [ABSTRACT FROM AUTHOR]

The molecular phylogenetic relationship among two species of genus Leiurus , from Saudi Arabia with additional comparative sequence data available from Egypt, Oman and Turkey is presented. The molecular phylogeny was performed using maximum parsimony, neighbor joining and bayesian inference. Our results indicate a clear deep splitting between the Western clade, which represented by L. quinuestriatus sequences from Egypt and those from the Eastern clade which encompassing different Leiurus species from Saudi Arabia, Oman and Turkey was shown. Also, the phylogenetic relationship represents additional support for the taxonomic status of Arabian Leiurus species. [ABSTRACT FROM AUTHOR]

Scorpionism is a serious public health problem in various regions of the world. In Brazil, a high number of accidents by scorpions have been reported. From 2014 to 2018, about 547,000 cases were recorded, resulting in 466 deaths. The scorpion Tityus stigmurus is the predominant species in the northeast of Brazil, being responsible for most scorpionism cases in this region. With the aid of the transcriptomic approach of the venom gland of this species, components as neurotoxins, antimicrobials, metal chelating peptides and hypotensins, have been identified and characterized in silico , showing different biologic activity in vitro. In addition, the neuronal, pancreatic, renal, and enzymatic effects have been demonstrated for the crude T. stigmurus venom. Therefore, the T. stigmurus scorpion venom constitutes a rich arsenal of bioactive molecules with high potential for therapeutic and biotechnological application. • T. stigmurus is the major cause of accidents in northeastern Brazil. • The venom is one of the most lethal for mices among Brazilian species. • The venom causes neuronal, pancreatic, renal damage, and has enzymatic properties. • The venom has neurotoxic, antimicrobial, hypotensive and metal chelating molecules. • Components of the venom have evident biotechnological and therapeutic potential. [ABSTRACT FROM AUTHOR]

Abstract Venoms of medically important scorpions from Buthidae family have been intensively studied, in contrast to non-buthid venoms, for which knowledge is scarce. In this work, we characterized the venom of a Diplocentridae species, Didymocentrus krausi , a small fossorial scorpion that inhabits the Tropical Dry Forest of Central America. D. krausi venom soluble fraction contains proteases with enzymatic activity on gelatin and casein. Mass spectrometry and venomic analysis confirmed the presence of elastase-like, cathepsin- O -like proteases and a neprilysin-like metalloproteinase. We did not detect phospholipase A 2 , C or D, nor hyaluronidase activity in the venom. By homology-based venom gland transcriptomic analysis, NDBPs, a β-KTx-like peptide, and other putative toxin transcripts were found, which, together with a p -benzoquinone compound present in the venom, could potentially explain its direct hemolytic and cytotoxic effects in several mammalian cell lines. Cytotoxicity of D. krausi venom was higher than the effect of venoms from two buthid scorpion species distributed in Costa Rica, Centruroides edwardsii and Tityus pachyurus. Even though D. krausi venom was not lethal to mice or crickets, when injected in mouse gastrocnemius muscle at high doses it induced pathological effects at 24 h, which include myonecrosis, weak hemorrhage, and inflammatory infiltration. We observed an apparent thrombotic effect in the skin blood vessels, but no in vitro fibrinogenolytic activity was detected. In crickets, D. krausi venom induced toxicity and paralysis in short periods of time. Graphical abstract Unlabelled Image Highlights • Didymocentrus krausi venom contains proteases and several types of peptides. • This venom is able to induce hemolysis and cytotoxicity, an effect produced by several components, including a p -benzoquinone. • In mice the venom is myonecrotic and induces weak hemorrhage and inflammation. • In insects this venom is toxic and induces paralysis. • No lethality was observed but in vitro this venom induces more toxicity than the venom of some buthids found in Costa Rica [ABSTRACT FROM AUTHOR]

Edge effects have drastically affected species living in tropical forests. However, understanding how species respond to edge effects remains a challenge, owing to the many factors involved and different responses of each species thereto. Here, we analyzed how the abundance of two sympatric scorpion species ( Tityus pusillus and Ananteris mauryi ) and their potential prey varied as a function of microhabitat changes (litter depth, dry mass, and leaf shape) from edge to interior forest habitats. We further analyzed the contribution of potential prey to scorpion abundance and reproductive periods. Data were collected monthly at three 300-m² transects/site at distances of 10, 100, and 200 m from the forest edge in a fragment of the Atlantic forest in northeastern Brazil, between April 2016 and March 2017. Scorpions responded differentially to edge effects, with A. mauryi abundance being similar along the edge-interior gradient, whereas T. pusillus had a higher abundance in the interior. As T. pusillus inhabit the top layer of the leaf litter, this species will possibly be more influenced by edge effects. In contrast, being a humicolous scorpion and inhabiting the bottom layers of leaf litter, A. mauryi would not be influenced by edge effects as much as T. pusillus . The reproductive period also was distinct between the two species, with T. pusillus reproducing in the dry season and A. mauryi in the rainy season. The oscillation in the abundance of different groups of prey at different periods maintained the overall prey abundance at a relatively constant level throughout the year, mitigating the effects of prey availability on the abundance and reproductive period of the scorpions. These results suggest that microhabitat exploitation is a key factor to sustain litter-dwelling scorpions in disturbed forest remnants and that T. pusillus can be an ecological indicator of edge effects. [ABSTRACT FROM AUTHOR]

The objective of this study was to characterize six different scorpion venoms using biological and biochemical methods, including a preliminary MS/MS and a post-translational modifications analysis. Despite the diversity of scorpion species of medical importance in Africa and Colombia, the venoms of these arachnids have been poorly studied in these two regions. We report the biochemical, electrophoretic, chromatographic profile, internal peptide sequences with a post-translational modification report, and a preliminary antitumor activity of five different scorpions of the Buthidae family, Androctonus amoreuxi, Babycurus jacksoni, Grosphus grandidieri, Hottentotta gentili and Tityus fuhrmanni , and one of the Scorpionidae family Pandinus imperator . No L-amino oxidase activity was detected in the evaluated venoms. Proteolytic activity using azocasein was detected only in G. grandidieri and P. imperator, indicating the possible presence of metalloproteinases in these two venoms. Proteolytic activity using NOBA was detected in all venoms indicating the possible presence of serine-proteinases. Phospholipase A 2 activity was detected in the venoms of P. imperator , G. grandidieri , H. gentili and A. amoreuxi , with P. imperator venom being the most active. All venoms analyzed contained defensin-like proteins, alpha toxins, metalloproteinases, neuropeptides, DBP affecting ion channels, DBP with antimicrobial activity, among others. Venoms from P. imperator , G. grandidieri and T. fuhrmanni showed a dose-dependent cytotoxic activity over MCF-7 cells. Only two isolated RP-HPLC fractions from P. imperator and T. fuhrmanni showed cytotoxic activity over MCF-7. No cytotoxic activity was found in the venoms from A. amoreuxi, B. jacksoni, and H. gentili . [ABSTRACT FROM AUTHOR]

Scorpions exhibit some of the lowest recorded water loss rates among terrestrial arthropods. Evaporative water loss to the surrounding environment occurs mainly through the integument, and thus its resistance to water loss has paramount significance for the ability of scorpions to tolerate extremely dry habitats. Cuticular hydrocarbons (HCs) deposited on the outer epicuticle play an important role in determining cuticular waterproofing, and seasonal variation in both cuticular HC quantity and composition has been shown to correlate with water loss rates. Precursor incorporation rates into cuticle HCs have been observed to be extremely low in scorpions compared with insects. We therefore used adult male Buthus occitanus (Buthidae) in order to test HC profile plasticity during acute exposure to 14 d and 28 d of experimental desiccation. Cuticular HC profile of hydrated scorpions was similar to that reported for several other scorpion species, consisting of similar fractions of n -alkanes and branched alkanes, with no evidence for unsaturation. Most abundant of the n -alkanes were n -heptacosane (C 27 ; 19 ± 2% of total HCs), n -nonacosane (C 29 ; 16 ± 1%) and n -hentriacontane (C 31 ; 11 ± 1%). Exposure to desiccation stress resulted in a significant increase in the total amount of extracted HCs, and in the relative abundance of branched alkanes at the expense of n -alkanes. Together with an increase in HC chain lengths, these changes mimic previously-reported seasonal variation among freshly-collected specimens. This indicates that scorpions respond to water shortage by regulating the properties of their passive integumental barrier to water loss. [ABSTRACT FROM AUTHOR]

Thromboelastometry was used to evaluate blood coagulation in anesthetized rats after intravenous administration of Tityus serrulatus scorpion venom (Tx). Tracheostomy followed by catheterization of the left jugular vein and right carotid artery were performed for Tx or Ringer's lactate solution injection and blood sample harvesting, respectively. Blood samples were obtained at the beginning of the experiments (baseline) and at two, five, 15, 30, and 60 min after intoxication. The following coagulation parameters were analyzed: CT (Clotting Time), CFT (Clotting Formation Time), Alpha Angle (α), MCF (Maximum Clot Firmness) and TPI (Thrombodynamic Potential Index). Toxin-induced hypercoagulability was demonstrated at the 15 and 60 min. We hypothesize Tx-induced hypercoagulability and enhanced clot formation could be explained by catecholamine release, systemic inflammatory response, and complement system activation, at least in the first hour after envenomation. Further studies are needed to determine the molecular mechanism of Tx-induced coagulopathy. [ABSTRACT FROM AUTHOR]

Cases of human envenomation by Centruroides pococki are exceptionally reported in human. We report a Class III human envenomation by C. pococki in Guadeloupe, French West Indies, with neuromuscular toxicity that has never been described before. Symptoms resolved within a few hours, without the need for intravenous scorpion-specific antivenom. • The epidemiology of scorpionism is still poorly known because of under-reporting. • Cases of human envenomation by Centruroides pococki are exceptionally reported in human. • We report a Class III human envenomation by C. pococki with neuromuscular toxicity. [ABSTRACT FROM AUTHOR]

Abstract: Among Middle Eastern countries, at least 52 species of scorpions, especially dangerous types, have been reported in Iran. This is more than any other country in the region. In addition, in Iran the recorded scorpion stings from 2001 to 2009 were more than 42,500 per year, of which, approximately 19.5 deaths have been reported each year, mostly in spring and summer. About 10 species are responsible for the reported envenoming which belong to the Buthidae family apart from Hemiscorpius lepturus which is a Hemiscorpiidae. The Buthidae family includes: Androctonus crassicauda, Mesobuthus eupeus, Odontobuthus doriae, Hottentotta saulcyi, Hottentotta schach, Compsobuthus matthiesseni, Orthochirus scrobiculosus, Apistobuthus pterygocercus and Olivierus caucasicus. A. crassicauda and H. lepturus are usually cited as the most dangerous species among Iranian scorpions. This article focuses on the main Iranian scorpions and their geographical distribution, especially those which are medically important and considered to be the more dangerous to human, and also attempts to demonstrate an accurate magnitude of scorpion stings in Iran. [Copyright &y& Elsevier]

Abstract: Given their medical importance, most attention has been paid toward the venom composition of scorpions of the Buthidae family. Nevertheless, research has shown that the venom of scorpions of other families is also a remarkable source of unique peptidyl toxins. The κ-KTx family of voltage-gated potassium channel (VGPC) scorpion toxins is hereof an example. From the telson of the scorpion Heterometrus laoticus (Scorpionidae), a peptide, HelaTx1, with unique primary sequence was purified through HPLC and sequenced by Edman degradation. Based on the amino acid sequence, the peptide could be cloned and the cDNA sequence revealed. HelaTx1 was chemically synthesized and functionally characterized on VGPCs of the Shaker-related, Shab-related, Shaw-related and Shal-related subfamilies. Furthermore, the toxin was also tested on small- and intermediate conductance Ca2+-activated K+ channels. From the channels studied, Kv1.1 and Kv1.6 were found to be the most sensitive (Kv1.1 EC50 =9.9±1.6μM). The toxin did not alter the activation of the channels. Competition experiments with TEA showed that the toxin is a pore blocker. Mutational studies showed that the residues E353 and Y379 in the pore of Kv1.1 act as major interaction points for binding of the toxin. Given the amino acid sequence, the predicted secondary structure and the biological activity on VGPCs, HelaTx1 should be included in the κ-KTX family. Based on a phylogenetic study, we rearranged this family of VGPC toxins into five subfamilies and suggest that HelaTx1 is the first member of the new κ-KTx5 subfamily. [Copyright &y& Elsevier]

It has previously been reported that several single-chain antibody fragments of human origin (scFv) neutralize the effects of two different scorpion venoms through interactions with the primary toxins of Centruroides noxius Hoffmann (Cn2) and Centruroides suffusus suffusus (Css2). Here we present the crystal structure of the complex formed between one scFv (9004G) and the Cn2 toxin, determined in two crystal forms at 2.5 and 1.9 Å resolution. A 15-residue span of the toxin is recognized by the antibody through a cleft formed by residues from five of the complementarity-determining regions of the scFv. Analysis of the interface of the complex reveals three features. First, the epitope of toxin Cn2 overlaps with essential residues for the binding of β-toxins to its Na+ channel receptor site. Second, the putative recognition of Css2 involves mainly residues that are present in both Cn2 and Css2 toxins. Finally, the effect on the increase of affinity of previously reported key residues during the maturation process of different scFvs can be inferred from the structure. Taken together, these results provide the structural basis that explain the mechanism of the 9004G neutralizing activity and give insight into the process of directed evolution that gave rise to this family of neutralizing scFvs. [ABSTRACT FROM AUTHOR]

Abstract: We provide a mitochondrial DNA-based phylogenetic hypothesis for 21 Tityus species collected in Venezuela, Trinidad, Brazil and Panama, including 12 taxa known to be toxic to humans. Our phylogenetic reconstruction is based on 850 nucleotides of the combined cytochrome oxidase subunit I and 16S rRNA genes for most species, and centered on Venezuelan scorpions owing to the detailed taxonomic and biogeographic information available for Tityus in this region. The principal phylogenetic result was the strong support for mtDNA clades representing geographical groupings associated with the Perijá mountain range, the Mérida Andes, or the central and eastern coastal ranges in Venezuela, suggesting that vicariance has been a potent force in the diversification of local scorpions. Venezuelan Tityus species have been organized by González-Sponga into three artificial morphological groups, “androcottoides”, “discrepans”, and “nematochirus”, based on the array of ventral carinae in metasomal segments II–IV. We also incorporated a fourth morphological group (“Tityus clathratus”), recently documented in Venezuela. Our results do not support the clustering of the species in the “androcottoides” and “discrepans” morphological groups, which include the majority of taxa of medical importance, but provided support for the “nematochirus” species group. T. clathratus was found to cluster with the Brazilian T. serrulatus and T. bahiensis. Divergence times of most clades are consistent with major events in the geological history of northern Venezuela and suggest that many Venezuelan Tityus species formed in the late Miocene and the Pliocene. In turn, we used the Tityus mtDNA phylogeny to determine the potential utility of phylogenetic systematics to predict Tityus venom antigenic reactivity by testing the recognition of T. nororientalis, T. discrepans, T. zulianus, T. perijanensis, and T. clathratus venoms by anti-T. discrepans horse antibodies. Cross-reactivity was significantly higher for the closely related eastern (T. nororientalis) and central coastal (T. discrepans) species in comparison to the distantly related Andean (T. zulianus) and Perijá (T. perijanensis) species. Reactivity of T. clathratus low mol. mass toxic components towards anti-T. serrulatus and anti-T. discrepans antivenoms was low, suggesting that venom components produced by the subgenus Archaeotityus (which encompass “clathratus” species) diverge antigenically from other Tityus scorpions. [Copyright &y& Elsevier]

Abstract: Venoms were collected from two scorpion species: Parabuthus leiosoma and Parabuthus pallidus from Kenya. Subcutaneous injection and oral toxicity tests of crude and pure fractions of scorpion venoms were done in Mus musculus (mice), Chilo partellus and Busseola fusca. The highest activity against C. partellus was found in P. leiosoma venom (LC50 0.689mg/50mg body weight). Bioassay-guided purification by a combination of cation-exchange (CE) and reverse-phase high-performance liquid chromatography (RP-HPLC) led to the isolation of three toxic peptides. A lepidopteran-selective toxin (P. leiosoma insect toxin, Plit) was isolated, and the partial N-terminal amino acid sequence (-KDGYPVDNANCKYE-) plus the molecular weight (6688.5Da) determined. A peptide with significant insect toxicity coupled with mild effects on mice (P. leiosoma toxin, Plt) was isolated, and the partial N-terminal amino acid sequence (-LCEKFKVQRLVELNCVD-) plus the molecular weight (6742.5Da) was determined. Another toxin with anti-mammalian activity (P. leisoma mammal-selective toxin, Plmt), and N-terminal partial amino acid sequence of ADVPGNYPLDKNGNRYY- plus a molecular weight of 7145.5Da was also isolated. Comparison of the partial N-terminal amino acid sequences with other toxins revealed that Plit shows high homology to other known insect toxins. Similarly, Plmt shows high homology with several birtoxin-like anti-mammalian toxins. Plt does not exhibit homology with any known scorpion toxin with combined anti-insect and anti-mammalian activity. [Copyright &y& Elsevier]

Abstract: Scorpions of the family Buthidae have been shown to be more desiccation resistant in comparison with sympatric Scorpionidae species. This has been attributed to the surface-dwelling existence of the former, which unlike most other scorpion species do not avoid environmental extremes by burrowing. Still, within Buthidae, the mesic Buthotus judaicus showed better osmoregulatory capacities than the xeric Leiurus quinquestriatus, largely as a result of its high resistance to water loss. However, B. judaicus exhibited poor ability to regulate its haemolymph osmolarity at 37 °C. In this study we report a sharp increase in water loss rates of B. judaicus at the 30–35 °C temperature range compared to that measured for L. quinquestriatus, which could explain the poor osmoregulatory performance of the former at higher ambient temperatures. The increase in water loss rates of B. judaicus at high temperatures is not coupled with a similar increase in respiratory rate, suggesting an increase in cuticular permeability. We suggest that this increase in cuticular permeability, which may result from a relatively low critical transition temperature, contributes to limiting the distribution of B. judaicus to habitats of moderate environmental conditions. [Copyright &y& Elsevier]

Abstract: Long-chain neurotoxins derived from the venom of the Buthidae scorpions, which affect voltage-gated sodium channels (VGSCs) can be subdivided according to their toxicity to insects into insect-selective excitatory and depressant toxins (β-toxins) and the α-like toxins which affect both mammals and insects. In the present study by the aid of reverse-phase HPLC column chromatography, RT-PCR, cloning and various toxicity assays, a new insect selective toxin designated as BjαIT was isolated from the venom of the Judean Black Scorpion (Buthotus judaicus), and its full primary sequence was determined: MNYLVVICFALLLMTVVESGRDAYIADNLNCAYTCGSNSYCNTECTKNGAVSGYCQWLGKYGNACWCINLPDKVPIRIPGACR (leader sequence is underlined). Despite its lack of toxicity to mammals and potent toxicity to insects, BjαIT reveals an amino acid sequence and an inferred spatial arrangement that is characteristic of the well-known scorpion α-toxins highly toxic to mammals. BjαITs sharp distinction between insects and mammals was also revealed by its effect on sodium conductance of two cloned neuronal VGSCs heterloguously expressed in Xenopus laevis oocytes and assayed with the two-electrode voltage-clamp technique. BjαIT completely inhibits the inactivation process of the insect para/tipE VGSC at a concentration of 100nM, in contrast to the rat brain Nav1.2/β1 which is resistant to the toxin. The above categorical distinction between mammal and insect VGSCs exhibited by BjαIT enables its employment in the clarification of the molecular basis of the animal group specificity of scorpion venom derived neurotoxic polypeptides and voltage-gated sodium channels. [Copyright &y& Elsevier]

Abstract: In the present study, crude venom of Mesobuthus gibbosus (Buthidae), a scorpion distributed all over Anatolia was isolated and purified by the Sephadex G-50 gel filtration and high pressure liquid chromatographic (HPLC) separation. Two of the five fractions (fractions 4 and 5) obtained from the Sephadex G-50 filtration and detected as lethal on mice and Musca domestica larvae in in vivo toxicity tests, were independently subjected to the HPLC separation. Only one of seven fractions (fraction 5.5*) obtained from the HPLC separation of the fraction 5 was found to be extremely lethal. Sodium dodecylsulfate polyacrylamide gel electrophoretic (SDS-PAGE) analysis of the crude venom and its chromatographic fractions demonstrated that crude venom consisted of peptides with molecular weights of 6500–210,000Da. The neurotoxic fraction 5.5* appeared as a single band of 28,000Da and two bands of 6200 and 22,000Da in SDS-PAGE under non-reducing and reducing conditions, respectively, suggesting that it might consist of two chains attached by a disulfide bridge. Fractions 5 and 5.5* inhibited monoamine oxidase A (MAO-A) of rat liver reversibly and non-competitively, in a concentration-dependent manner. Fraction 5.5* appeared as a potent and specific MAO-A inhibitor with a Ki value of 0.12mg venom proteinml-1. The inhibitory effect of venom peptide 5.5* on MAO-A was found to be dependent on the preincubation time suggesting that the peptide binds to some site other than the substrate-binding site. Results of the present study demonstrated that M. gibbosus venom contains a peptide with specific MAO-A inhibitory activity which may be responsible for the anxiogenic effects of the scorpion venoms on animals and humans. [Copyright &y& Elsevier]

The divergence of Buthidae, the most abundant family of scorpions, has relied thus far on anatomical and morphological features, but still remains controversial. However, much information has accumulated on Buthidae long-chain scorpion toxins affecting neuronal sodium channel conductance (α- and β-toxins) and their pharmacology. Therefore, we constructed a toxin evolutionary tree, which together with recent data on toxin gene organization, toxin structures, and worldwide dispersion, sheds light on toxin and hence, scorpion divergence. Based on these data, we suggest that in the ancient world, the ancestral long-chain toxins affecting sodium channels developed into β-like toxins, which most likely developed into α- and β-toxins before the separation of South America from Africa. Subsequently, in the Old World, mostly excitatory and depressant toxins developed from the ancestral β-like toxin and in the New World a new type of toxin group with β-toxin structure but α-toxin activity developed from the β-toxins. Assisted by the worldwide distribution of toxins and the zoogeographical dispersion of the studied genera in Asia and Africa (Old World) and in South and North America (New World), we suggest a route of divergence for some of the Buthidae scorpions, a task that has reached a standstill when morphological and anatomical features were used. [Copyright &y& Elsevier]

The venoms of buthid scorpions are known to contain basic, single-chain protein toxins (alpha toxins) consisting of 60–70 amino acid residues that are tightly folded by four disulfide bridges. Here we describe isolation and sequencing of three novel putative alpha toxins (AamH1-3) from the venom of the North African scorpion, Androctonus amoreuxi, and subsequent cloning of their precursor cDNAs from the same sample of venom. This experimental approach can expedite functional genomic analyses of the protein toxins from this group of venomous animals and does not require specimen sacrifice for cloning of protein toxin precursor cDNAs. [Copyright &y& Elsevier]

A checklist of the scorpion fauna of Saudi Arabia was reviewed and scrutinized published scorpion records considering new taxonomic findings and geographical distribution data. A new checklist to the scorpion fauna of Saudi Arabia is presented. The listed species consisting of 26 species belong to 15 genera and the four families Buthidae (12 genera, 21 species), Diplocentridae (one genus, one species), Hemiscorpiidae (one genus, one species), and Scorpionidae (one genus, three species). The list is dominated by members of the family Buthidae C. L. Koch, 1837 (85.3% of total species) and the genus Compsobuthus is the most species-rich taxon. In addition, a total of 10 dubious records were removed from the list and listed separately pending validations by specimens collected in the country. A dichotomic identification key to the Saudi Arabia scorpion species has been provided. [ABSTRACT FROM AUTHOR]