Scorpion Family Research Articles

An Atlas of Book Lung Fine Structure in the Order Scorpiones (Arachnida)

The fine structure of the book lungs of scorpions is diverse and phylogenetically informative, but has not been comprehensively investigated across the major lineages of the order. In this contribution, we present a fully illustrated atlas of the variation in book lung fine structure among 200 exemplars from 100 genera and 18 families of extant scorpions. We document variation in the surface sculpturing of the respiratory lamellae, the edges of the lamellae in the atrial chamber, and the posterior valvelike edges of the spiracles. These data provide insights into the phylogenetic relationships among Recent scorpions at several branches of the tree.

A ‘living fossil’ from Central Asia: The morphology of Pseudochactas ovchinnikovi Gromov, 1998 (Scorpiones: Pseudochactidae), with comments on its phylogenetic position

Pseudochactas ovchinnikovi Gromov, 1998, arguably the most remarkable scorpion discovered during the last century, inhabits an isolated, mountainous region of southeastern Uzbekistan and southwestern Tajikistan, Central Asia. This scorpion displays several morphological characters unique among Recent (extant) scorpions, including a unique trichobothrial pattern and a mixture of other characters, some potentially synapomorphic with Buthidae C.L. Koch, 1837, others with the nonbuthid scorpion families, particularly Chaerilidae Pocock, 1893. Consequently, a monotypic family, Pseudochactidae Gromov, 1998 was created to accommodate it. Although there is widespread agreement that Pseudochactas Gromov, 1998 is basal within Recent scorpions, its precise phylogenetic position remains a matter of debate. Three competing hypotheses have been proposed to account for its position: (1) sister group of all Recent scorpions; (2) sister group of Buthidae; (3) sister group of Chaerilidae. Despite the importance of Pseudochactas in determining the basal relationships among Recent scorpions, several important character systems, including the hemispermatophore and the ovariuterus, have not yet been studied in the genus. There are also several misconceptions regarding some of the character systems (e.g., trichobothria and carinae) that have been studied. In this contribution, we provide a detailed, fully illustrated reexamination of the morphology of Pseudochactas, including the first descriptions of its hemispermatophore, ovariuterus, and pectinal peg sensillae. We discuss the implications of these and other characters for the phylogenetic position of this ‘living fossil’ and conclude that Hypothesis 2, sister group of Buthidae, is the most plausible of the alternatives, all of which await further testing in a rigorous phylogenetic analysis.

Moving pieces in a taxonomic puzzle: Venom 2D-LC/MS and data clustering analyses to infer phylogenetic relationships in some scorpions from the Buthidae family (Scorpiones)

The Buthidae is the most clinically important scorpion family, with over 500 species distributed worldwide. Taxonomical positions and phylogenetic relationships concerning the representative genera and species of this family have been mostly inferred based upon comparisons between morphological characters. Yet, some authors have performed such inferences by comparing some structural properties of a few selected molecules found in the venoms from these scorpions. Here, we propose a novel methodology pipeline designed to address these issues. We have analyzed the whole venoms from some species that exemplify peculiar cases in the Buthidae family ( Tityus stigmurus, Tityus serrulatus, Tityus bahiensis, Leiurus quinquestriatus quinquestriatus and Leiurus quinquestriatus hebraeus), by means of a proteomic approach using a 2D-LC/MS technique. The molecules found in these venoms were clustered according to their physicochemical properties (molecular mass and hydrophobicity), by using the machine learning-based Weka software. The clusters assessment, along with the number of molecules found in a given cluster for each scorpion, which assigns for the venom and structural family complexities, respectively, was used to generate a phenetic correlation tree for positioning these species. Our results were in accordance with the classical taxonomy viewpoint, which places T. serrulatus and T. stigmurus as very close species, T. bahiensis as a less related species in the Tityus genus and L. q. quinquestriatus and L. q. hebraeus with small differences within the same species ( L. quinquestriatus). Therefore, we believe that this is a well-suited method to determine venom complexities that reflect the scorpions' evolutionary history, which can be crucial to reconstruct their phylogeny through the molecular evolution of their venoms.

The giant and complex genital plug of the asper group of Bothriurus (Scorpiones, Bothriuridae): morphology and comparison with other genital plugs in scorpions

The genital plugs of two species of the asper group of Bothriurus (Scorpiones: Bothriuridae) are described and compared with other genital plugs reported in the family Bothriuridae. In both species, B. asper and Bothriurus sp., the genital plug is cone-shaped and formed by fusion of the basal lobes of the hemispermatophore. Fusion is complete in B. asper and the surface of the plug has many microspines that anchor it to the female genital atrium. In Bothriurus sp., the basal lobes are partially fused, but free on the dorsal side, and the plug has a smooth surface with a dorsal curvature. Both genital plugs completely fill the genital atrium of inseminated females, pressing against the cuticular wall of the atrium. Given the large size and complex shape, the genital plug of the B. asper group is unique, not only among Bothriuridae, but in the order Scorpiones. This new type of genital plug resembles the genital plugs of the scorpion families Urodacidae and Vaejovidae. A comparison of the four major types of genital plugs reported in Bothriurus species and some other bothriurids is provided, as well as a comparison with other genital plugs reported in more distantly related families of scorpions.

Functional morphology of spermatophores and female genitalia in bothriurid scorpions: genital courtship, coercion and other possible mechanisms

AbstractScorpions use sclerotized spermatophores for sperm transfer. The family Bothriuridae has one of the most complex scorpion spermatophores, with a distinct capsule and lamella. This study evaluates the viability of hypotheses relating to the evolution of animal genitalia that attempt to explain the functional morphology observed in spermatophores and female genitalia of some members of this scorpion family. These hypotheses are: female choice (internal courtship), conflict of interests (morphologically forced insemination) and lock‐and‐key (interspecific mechanical incompatibility). Observations of the mating sequences of 13 bothriurid and one buthid scorpion were recorded. The histology of female atrium was analysed. The data suggest that: (1) a genital copulatory courtship (sexual stimulation through male genitalia) could be a widespread mechanism among the capsules of the studied spermatophores; the wall of the female genital atrium in Brachistosternus as well as of other genera is usually rubbed by spines, tubercles or capsular lobes of spermatophores; the female genital atrium is relatively soft, elastic and uniform among different species; (2) morphological coercion might be admissible only when capsular lobes are very well developed, as females will have difficulty in disengaging by themselves from the large lobes if they attempt to interrupt sperm transfer; this mainly occurs in Bothriurus bonariensis; (3) observations of matings among closely related species indicate that the lock‐and‐key hypothesis is unable to explain spermatophore morphology in the studied species; however a certain degree of mechanical incompatibility occurs during interspecific mating between two sister species (B. bonariensis and B. chacoensis) owing to differences in capsular lobes and post‐insemination behaviour; (4) these hypotheses might not be directly applied to simple spermatophores of the Buthidae Zabius fuscus. The results indicate that even though one genital mechanism can be more frequent than others, they can also exist together, not only in different genera but also in a single species (e.g. simultaneous occurrence of genital sexual stimulation and genital coercion in B. bonariensis). Indirectly these data suggest that the hypotheses most frequently quoted to explain genital morphology are not mutually exclusive.

New insight on scorpion divergence inferred from comparative analysis of toxin structure, pharmacology and distribution

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.

Australian scorpion stings: a prospective study of definite stings

There is little information on scorpion stings in Australia. The aim of this study is to describe the circumstances and clinical effects of stings by Australian scorpions. Cases of scorpion stings were collected prospectively from calls and presentations to Australian poison information centres and emergency departments from February 2000 to April 2002. Only definite scorpion stings where the scorpion was immediately collected and expertly identified were included. There were 95 patients, 33 males and 62 females, with a mean age of 32 (SD 19.5; range 1–71) and 23 children (age<15 years). Three families of scorpions caused all stings: Buthidae (79), Bothruiridae (11, all Cercophonius spp.) and Urodacidae (five, all Urodacus spp.). The majority of stings (76%) were by one genus of scorpion Lychas spp. Seventy one percent of stings occurred between 6pm and 8am and 82 (86%) occurred indoors. Sixty percent of stings occurred on distal limbs. The median duration of effects was 6 h (interquartile range (IQR): 1–24 h). Immediate localised pain occurred in all cases and was severe in 76 cases (80%). Other local effects included red mark/redness (66%), tenderness (35%), numbness (12%) and paraesthesia (11%). Minor systemic effects (nausea, headache and malaise) occurred in 11% of cases. There were no deaths or major systemic envenoming. Less severe effects were observed for the larger Urodacus species, compared to Lychas spp. Scorpion stings in Australia do not appear to cause severe or life-threatening effects, even in children. This differs from other parts of the world, where severe envenoming is reported. The major clinical effect is severe pain, consistent with other scorpion stings. Most stings occurred indoors and at night.

High-level systematics and phylogeny of the extant scorpions (Scorpiones: Orthosterni)

A number of authors (e. g. Birula, 1917a, 1917b; Mello-Leitão, 1945; Stockwell, 1989) addressed above-level systematics of extant scorpions, and accepted the grouping of scorpion families in several superfamilies. At the same time, Kjellesvig-Waering (1986) classified all extant scorpions under the same superfamily, Scorpionoidea. Sissom (1990) and Fet et al. (2000) did not list any superfamilies, considering the systematic situation above family (and often at the family level as well) unresolved. Most recently, Lourenço (2000a) listed six superfamilies, largely following the unpublished but important study of Stockwell (1989). The goal of this paper is to address scorpion systematics and phylogeny above genus level. We conducted a comprehensive, cladistic morphological analysis of 90 extant genera (over 150 species) of scorpions belonging to all recognized families. We especially concentrated on relationships among so-called “chactoid” scorpions, where subfamilies, tribes, and subtribes were revised and/or established. The family Chactidae was given a special attention due to the number of phylogenetic and taxonomic issues that were revised. In addition, we addressed the status of a recently discovered, unique relict family Pseudochactidae, and the systematic relationships within Iuridae. As a result of intensive study, we propose a number of sweeping changes in current scorpion taxonomy; the results of analyses leading to these changes are discussed in detail. The category of parvorder, subordinate to infraorder, is introduced for the first time in arachnid systematics. Four extant parvorders are recognized within the scorpion infraorder Orthosterni: Buthida, Chaerilida, Pseudochactida, and Iurida. Six extant superfamilies are recognized: Buthoidea, Chactoidea (=Vaejovoidea, syn. n), Chaeriloidea, Iuroidea (new), Pseudochactoidea (new), and Scorpionoidea (=Bothriuroidea, syn. n). Parvorders Buthida, Chaerilida and Pseudochactida are monotypic, each including a single superfamily; parvorder Iurida includes three superfamilies (Chactoidea, Iuroidea, and Scorpionoidea). We recognize 14 extant scorpion families: Bothriuridae, Buthidae, Caraboctonidae, Chactidae, Chaerilidae, Euscorpiidae, Iuridae, Liochelidae, Microcharmidae, Pseudochactidae, Scorpionidae, Superstitioniidae, Urodacidae, and Vaejovidae. Superfamilies Chaeriloidea and Pseudochactoidea are monotypic; superfamily Buthoidea includes two families (Buthidae and Microcharmidae). Superfamily Iuroidea includes two families (Caraboctonidae and Iuridae); subfamily Caraboctoninae (formerly in Iuridae) is elevated to the family rank. Superfamily Chactoidea includes four families: Chactidae, Euscorpiidae, Superstitioniidae (=Troglotayosicidae, syn. n), and Vaejovidae. Within Chactidae, three subfamilies are established: Chactinae, Brotheinae, and Uroctoninae. Within Chactinae, two tribes are established: Chactini and Nullibrotheini, new tribe (monotypic). Within new subfamily Brotheinae, two tribes are established: Brotheini and Belisariini (monotypic). Within Brotheini, two subtribes are established: Brotheina and Neochactina, new subtribe; the latter is based on a new genus, Neochactas, gen. n. Within Brotheina, genera Cayooca, Guyanochactas, and Taurepania are synonymized with Broteochactas. Subfamily Uroctoninae is restored from synonymy under Vaejovidae and transferred to Chactidae; it includes genera Uroctonus and Anuroctonus (the latter transferred from the erstwhile Iuridae). Family Troglotayosicidae is abolished, and its two genera are transferred to other families: Troglotayosicus, to Superstitioniidae; and Belisarius, to Chactidae. Subfamily Belisariinae is downgraded to the tribe rank and transferred to Chactidae (subfamily Brotheinae). Superfamily Scorpionoidea includes four families: Bothriuridae, Liochelidae (=Hemiscorpiidae, syn. n.), Scorpionidae (=Diplocentridae, syn. n.), and Urodacidae (=Heteroscorpionidae, syn. n). Family Diplocentridae is downgraded to the subfamily rank in Scorpionidae. Subfamily Nebinae is downgraded to the tribe rank in Diplocentrinae. Family Hemiscorpiidae is downgraded to the subfamily rank in Liochelidae. Family Heteroscorpionidae is downgraded to the subfamily rank in Urodacidae. We provide detailed classification, taxonomic history, and diagnoses of all recognized scorpion taxa above genus level. The phylogeny and biogeographic implications are discussed. As an addition, we present, among other materials, results of the first pilot high-level scorpion DNA phylogeny, including representatives of seven families spanning all four parvorders. Both morphological analysis and DNA sequence analysis support the primitive nature of parvorders Pseudochactida, Buthida, and Chaerilida, as opposed to the derived position of parvorder Iurida. Especially remarkable is the parvorder Pseudochactida, which exhibits many primitive features. Within Iurida, the superfamily Iuroidea is firmly established as a basal group, and Scorpionoidea, as the most derived group. Phylogeny within Chactoidea shows ancient nature of many clades, as our analysis reveals hitherto unexpected relationships between a number of genera and tribes.

A new family of fossil scorpions from the Early Cretaceous of Brazil

A new family, new genus and species of fossil scorpions are described from the Early Cretaceous of Brazil, Santana formation, Crato area in the state of Ceara. These fossils can be classified together with extant families within the Scorpionoidea. This suggests that these modern scorpions belong to lineages present at least for 110 Myr.

The scorpion families and their geographical distribution

A synoptic table is proposed for the families and genera of scorpions currently regarded as valid. Because there is considerable disagreement about the classification of scorpions, many changes are to be expected in the future. The classification proposed here is followed by considerations regarding the geographical distribution of each family.

Production of a Functional Anti-Scorpion Hemocyanin ScFv in Escherichia coli

A58 is a murine monoclonal antibody raised against the internal dimeric subunit Aa 1 of the hemocyanin of the scorpion Androctonus australis. When A58 is tested against a range of related hemocyanins, it exhibits cross-reactivity with a limited number of scorpion species. All of them belong to a single Scorpion Family: the Buthidae. We have utilized a bacterial expression-export system in which the variable regions of A58 are expressed as a single-chain variable fragment (scFv). Polymerase chain reaction (PCR) was used for the cloning and modification of the heavy and light variable regions which were assembled into a scFv. After insertion into a vector which contains the pectate lyase signal sequence from Erwinia caratovora for periplasmic expression, a scFv protein was produced in high yield as a soluble and functional protein. The bacterial produced A58 scFv has binding properties similar to those of the original murine antibody. It binds specifically the heterodimeric subunit of Androctonus australis hemocyanin, cross-reacts with only one subunit of each Buthidae investigated, and blocks the recognition of the hemocyanin by antibody A58 in competitive enzyme-linked immunosorbant assay. Previous reports have demonstrated the value of monoclonal antibodies in taxonomical and molecular evolution studies. A58scFv is the first of a new generation of antigen-binding proteins which should prove useful both in taxonomical studies and in the analysis of VH-VL structure-function relationships of antibodies.

Synaptonemal complex formation in male scorpions exhibiting achiasmate meiosis and structural heterozygosity

Synaptonemal complex (SC) formation was studied in testicular material from individuals of a number of species from two families of Australian scorpions; Buthidae and Scorpionidae. These scorpions exhibit unusual cytogenetic features including achiasmate male meiosis, interchange heterozygosity, and centromeric fusion–fission and inversion heterozygosity. The synaptic behaviour of chromosomes involved in these rearrangements was studied from zygotene to metaphase I, using both meiotic chromosome preparations and techniques for examination of the SCs. Multivalent associations present during the achiasmate meiosis of both buthid and scorpionid scorpions are retained from prophase to metaphase I, unlike those present in polyploid achiasmate Bombyx females. Further evidence suggests that synaptic adjustment does not occur generally in achiasmate scorpionid inversion heterozygotes. However, for some inversions, pairing is seen to become more heterosynaptic from late prophase to metaphase I and this may be related to the pairing maintenance system during achiasmate meiosis in these specialized organisms.Key words: synaptonemal complex, achiasmate meiosis, heterozygosity, interchange, inversion.

AGGRESSION, DENSITY, AND SEXUAL DIMORPHISM IN CHERNETID PSEUDOSCORPIONS (ARACHNIDA: PSEUDOSCORPIONIDA).

The determinants of sexual dimorphism in a family of false scorpions (Pseudoscorpionida: Chernetidae) were investigated experimentally and with a literature analysis of comparative morphometric and habitat data. Species vary in the extent to which males and females differ in size of the pedipalps, and, in particular, in size of the pedipalpal chelae. A statistical analysis of dimorphism patterns within the Chernetidae suggests that dimorphism is a highly variable condition, relatively unconstrained by phylogenetic influences. The evolution of species with enlarged male pedipalps appears to be associated with a change from nonpairing to pairing sperm-transfer behavior and with aggressive mate acquisition by males. Experiments with Dinocheirus arizonensis demonstrate a strong correlation between male combat ability and chela size. Manipulations also suggest that superior combat ability of large males results in increased mating success only under high-density conditions. The greater success in spermatophore transfer among large males can be attributed to increased opportunity at high density for large males to interrupt matings and aggressively displace smaller males. Comparative analysis showed a positive correlation between density and enlarged male chela size across chernetid species.

Preliminary notice on a Silurian Scorpion (Palaeophonus nuncius) from the Isle of Gothland

In his paper on the ‶Fossil Scorpions of Scotland,″1 Mr B. N. Peach has said: ‶The dawn of the scorpion family must have been at a much earlier period,2 and we may hope that their remains may yet turn up in the Devonian and Silurian plant-beds.″ This hope has now been fulfilled, since I have discovered a scorpion in the Upper Silurian beds of the Swedish Island, Gothland. It was found near the town of Wisby, not far from its southern walls, in a thin bed of shale or clay, which was previously known to be rich in remains of Pterygoti, Annelida, Brachiopoda, Trilobites, &c. The scorpion, a photograph of which, twice the natural size, is subjoined, will be described in detail by Professor Tamerlau Thorell, the eminent author of several works on recent Scorpions, in a joint paper with me. For the present, I give a few preliminary remarks on it, for as their own strata contain so many important species of fossil scorpions, it may be of special interest to Scottish naturalists. The Gothland fossil consists entirely of the thin chitinous coating of the animal, which had apparently been entombed in the stratum after all soft animal tissues had been dissolved. It has consequently suffered much through the pressure of the superimposed limestone strata, and has been much folded and wrinkled. The colour is brownish yellow and chestnut, and agrees thus with that of recent scorpions. The main parts of the body agree also with theirs. We find