Microallopatry caused strong diversification in Buthus scorpions (Scorpiones: Buthidae) in the Atlas Mountains (NW Africa)

The immense biodiversity of the Atlas Mountains in North Africa might be the result of high rates of microallopatry caused by mountain barriers surpassing 4000 meters leading to patchy habitat distributions. We test the influence of geographic structures on the phylogenetic patterns among Buthus scorpions using mtDNA sequences. We sampled 91 individuals of the genus Buthus from 51 locations scattered around the Atlas Mountains (Antiatlas, High Atlas, Middle Atlas and Jebel Sahro). We sequenced 452 bp of the Cytochrome Oxidase I gene which proved to be highly variable within and among Buthus species. Our phylogenetic analysis yielded 12 distinct genetic groups one of which comprised three subgroups mostly in accordance with the orographic structure of the mountain systems. Main clades overlap with each other, while subclades are distributed parapatrically. Geographic structures likely acted as long-term barriers among populations causing restriction of gene flow and allowing for strong genetic differentiation. Thus, genetic structure and geographical distribution of genetic (sub)clusters follow the classical theory of allopatric differentiation where distinct groups evolve without range overlap until reproductive isolation and ecological differentiation has built up. Philopatry and low dispersal ability of Buthus scorpions are the likely causes for the observed strong genetic differentiation at this small geographic scale.     

Evidence for recombination in scorpion mitochondrial DNA (Scorpiones: Buthidae)

There has been very little undisputed evidence for recombination in animal mitochondrial DNA (mtDNA) provided so far. Previous unpublished results suggestive of mtDNA recombination in the scorpion family Buthidae, together with cytological evidence for a unique mechanism of mitochondrial fusion in that family, prompted us to investigate this group in more details. First, we sequenced the complete mtDNA genome of Mesobuthus gibbosus, and chose two genes opposing each other (16S and coxI). We then sequenced 150 individuals from the natural populations of four species of Buthidae (Old World genera Buthus and Mesobuthus). We observed strong evidence for widespread recombination through highly significant negative correlations between linkage disequilibrium and physical distance in three out of four species. The evidence is further confirmed when using five other tests for recombination and by the presence of a high amount of homoplasy in phylogenetic trees.     

Allozymic differentiation of Tunisian populations of Androctonus species and Buthus occitanus (Scorpiones: Buthidae)

We examined the population structure and phylogeny of Buthus occitanus (Amoreux, 1789), Androctonus amoreuxi (Audouin & Savigny 1812) and Androctonus australis (Linnaeus, 1758) in Tunisia, using horizontal starch gel and polyacrylamide gel electrophoresis to resolve allozymes at 18 loci. Populations of B. occitanus and A. amoreuxi showed little genetic variation, whereas A. australis populations showed moderate genetic variation. Moreover, despite the restricted dispersal abilities of these species, the allozyme analysis indicated very low levels of intraspecific population differentiation. The Island model of population differentiation best fitted the intraspecific variation, both for mainland populations and for the slightly more differentiated populations from two Mediterranean islands. No diagnostic, fixed alleles were observed between the species of Androctonus , which concurs with the results of nuclear ribosomal DNA analysis. Two subspecies of A. australis , A. a. garzonii Goyffon & Lamy, 1973 and A. a. hector Vachon, 1948, were not resolved by a phylogenetic analysis of the allozyme data. The most likely reasons for the slight population differentiation are either low mutation rates or recent range extensions promoted by human activities. The possibility of indirect gene flow between Androctonus species should also be explored.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 81 , 255–265.     

A fossil scorpion Tityus geratus new species (Scorpiones: Buthidae) from Dominican Amber

A fossil scorpion, Tityus geratus (Scorpioncs: Buthidae) n. sp., is described from Dominican amber. This is the third described amber Tityus sp. and the third Dominican amber scorpion. On the basis of the amber finds and available knowledge on the present distribution of Tityus spp. in the Antilles, the vicariance model of Caribbean biogeography can be evoked to best explain the present distribution of this genus.     

Sexual dimorphism and reproductive behavior in the Brazilian scorpion Tityus pusillus (Scorpiones,Buthidae)

We studied sexual dimorphism (SD) and reproductive behavior in the litter‐dwelling scorpion, Tityus pusillus. SD was determined by measuring seven body structure attributes (prosoma, mesosoma, and metasoma lengths, and pedipalp chelae and metasomal segment V lengths and widths) in 634 individuals (211 males and 423 females) from the Arachnological Collection of the Universidade Federal de Pernambuco. Reproductive behavior was observed in 55 couples during nocturnal activity observations conducted in the laboratory. In addition, we evaluated gestation time, hemispermatophore replacement, and sequential courtship. Individuals of T. pusillus exhibited typical reproductive behavior, with a short courtship time (averaging 10±5 min). Males only accepted new partners at least 48 h after first mating, suggesting that this period may be necessary for hemispermatophore production. Females did not accept new partners for 24–48 h after their first mating. The average gestation period was 85±12 d, ranging 60–100 d. Our results showed a more complex picture of SD than previously described for this species, including features characteristic of both sexual size dimorphism (SSD) and sexual body component dimorphism in scorpions. In general, considering the relatively large size of the prosoma and mesosoma in T. pusillus, it seems reasonable to conclude that female‐biased SSD exists in the species, and that male‐biased sexual body component dimorphism is evident in the metasoma and chelae.     

Eight polymorphic microsatellite markers developed in the Chinese scorpion, Mesobuthus martensii (Scorpiones: Buthidae)

Eight polymorphic di- and trinucleotide microsatellite loci were developed in the Chinese scorpion, Mesobuthus martensii. The expected heterozygosity at these loci ranges from 0.019 to 0.860, with the observed allele numbers varying from two to 25. Overall, there were no deviations from Hardy-Weinberg equilibrium and no observed linkage disequilibrium after Bonferroni correction. Cross-species amplification of these loci in Mesobuthus eupeus revealed that five loci can amplify successfully in this species. The polymorphic microsatellite DNA markers reported here should provide helpful means to address questions concerning phylogeographical patterns and evolutionary history of M. martensii and closely related species.     

Parasitism of bark scorpion Centruroides exilicauda (Scorpiones: Buthidae) by entomopathogenic nematodes (Rhabditida: Steinernematidae; Heterorhabditidae)

In laboratory bioassays, Steinernema glaseri Steiner, Steinernema riobrave Cabanillas, Poinar & Raulston, Heterorhabditis bacteriophora Poinar, and Heterorhabditis marelatus Liu & Berry were capable of infecting and killing the bark scorpion, Centruroides exilicauda (Wood). Steinernema feltiae (Filipjev) and Steinernema carpocapsae (Weiser) failed to infect C. exilicauda at 22 degrees C. S. glaseri, H. marelatus, and H. bacteriophora caused significant mortality at 22 degrees C, indicating the potential role of these parasites as a biocontrol option. Efficacy of S. glaseri and H. bacteriophora was reduced in an assay conducted at 25 degrees C. Only S. glaseri was able to reproduce in the target host. Dissection of scorpions at the end of the experimental periods revealed inactive juvenile S. riobrave, H. marelatus, and H. bacteriophora nematodes. Both mermithid and oxyurid nematodes have been documented as nematode parasites of scorpions, but rhabditids have not been reported until now. Field studies are warranted to assess the usefulness of entomopathogenic nematodes as biocontrol agents of bark scorpions.     

A new relictual buthid scorpion from the region of the Great Rift Valley in Kenya (Scorpiones,Buthidae)

A new genus and species of peri-Saharian buthid scorpion is described on the basis of single specimen collected in the Great Rift Valley, North of Kenya. This new scorpion taxon represents yet another endemic relict element for the faunas of the peri-Saharian regions. Comments are also included on the evolution of the Sahara and peri-Saharian regions and its possible consequences on the distribution of the extant scorpion fauna.     

Complements to the description of Tityus dedoslargos (Scorpiones: Buthidae)

The female of the Costarican scorpion Tityus dedoslargos Francke and Stockwell, 1987 is described for the first time and new data on its morphological variation and natural history are given. The female differs from the male mainly in having an enlarged basal median lamellae on the pectines, and lacking modified pedipalps. The species type locality relocated. This species is recorded from only two Costarican provinces: San Jose and Puntarenas.     

Development of respiratory structures in embryos and first and second instars of the bark scorpion,Centruroides gracilis (Scorpiones: Buthidae)

The SEM was used to study the development of respiratory structures in successive stages in relation to the overall changes occurring in the scorpions. Book lung development is a slow process, starting with spiracles and a sac‐like atrium in the early embryo and continuing lamellar formation to 150 or more in the adult. In the embryo, the primordial epithelial cells become aligned in a planar pattern as they secrete granules of material that aggregate spontaneously to form the cuticular walls of the lamellae. A blade‐like structure is formed consisting of cells sandwiched within the two cuticle walls they secreted. These cells are in the primordial air channel. The adjacent hemolymph channel is nearly devoid of cells, but cross‐bridges develop and help stabilize the cuticle walls and maintain the width of the channel. The cells in the primordial air channel undergo cytolysis, leaving it open for air except for cuticular cross‐bridges. Development continues in the newborn (first instars); the air channels of some lamellae still contain cells and are not yet functional for gas exchange. The first instars are weak and relatively inactive. They climb up on the mother's dorsum until the first molt (about 8 days). With the cuticular walls of the lamellae in place, cells adhering to the wall in the hemolymph channel produce a thin, new tissue layer (epithelium) on the lamellar wall facing the hemolymph channel. This layer has many discontinuities as though it is slowly developing. Formation of the tissue layer and cytolysis of the cells in the air channels continue through the first molt in which little book lung cuticle is shed as exuvium. The air channels of the second instars (foraging nymphs) are now cell free and open for air passage except for the cross‐bridges. The tissue layer is still incomplete and continues to be formed. It may provide the hypodermal primordium for cuticle replacement in later molts, but development was not studied beyond the second instar except for comparison with book lungs in the adult. The blade‐like lamellae in the adult are larger and more numerous than in the second instar, but in the anterior book lung the shape of the cuticle wall and cross‐bridges and the widths of the air and hemolymph channels are about the same as in the second instar. The air channels in the posterior part of the lamellae have distinctive, vein‐like space‐holders. The similarity of the adult anterior lamellae with those in the second instar suggests retention of this part through the 4–5 molts to maturation, and/or cell processes like those in the embryo are repeated, but this needs to be examined in further studies of cell and cuticle changes before and during the molts. J. Morphol., 2008. © 2008 Wiley‐Liss, Inc.     

The genetic population structure of Buthus occitanus (Scorpiones: Buthidae) across the Strait of Gibraltar: calibrating a molecular clock using nuclear allozyme variation

I assess here the importance of the Strait of Gibraltar as a barrier to gene flow for populations of the scorpion Buthus occitanus . This polytypic buthid scorpion occurs in Europe and in North Africa where it is morphologically more diverse. The phylogenetic relationship between B. occitanus populations across the Strait of Gibraltar is investigated by nuclear allozymes analysis (15 loci scored). Phylogenetic analysis based on estimated gene frequency data results in a tree topology that divides the populations into three clades, i.e. a European, an Atlas (= Morocco samples) and a Tell-Atlas clade (= Tunisian samples). The Tell-Atlas clade grouped with the European clade with a rather high bootstrap support of 70%. Within these clades low levels of genetic variability are observed. Calibrating a molecular clock under the assumption that the European populations are autochthonous and have been isolated from the North African for at least 5.33 Myr reveals a divergence rate of 0.060 genetic distance (D) per Myr estimated between European and Moroccan samples and 0.036D Myr⁻¹ between European and Tunisian samples, respectively.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 81 , 519–534.     

A new species of Tityus (Scorpiones: Buthidae) from Turimiquire, Venezuela

We describe a new species of Buthid scorpion, Tityus quirogae, from the Turimiquire mountains, eastern side of the La Costa range, Monagas and Sucre States, Venezuela. It is morphologically similar to T. nematochirus and T. meridanus. It differs from these species in the distribution of the dorsal femoral trichobothria and in the following combination of characters: (1) I caudal segment with two parallel ventral keels. Caudal segments II to IV with ventral keels that are double in the extremes of the segments and single in the middle, (2) noticeable sexual dimorphism, especially in pedipalp shape; the male chelae are markedly thin and long, (3) number of pectineous teeth (male: 18 in each pecten; female: 18 in the right pecten and 19 in the left one), and (4) number of denticle rows in the movable finger of the right chela (16 in both sexes). T. quirogae is the first species of this genus, in the Northeastern region of Venezuela, with thin and elongated pedipalps.     

Role of venom quantity in the feeding behavior of Jaguajir rochae (Scorpiones: Buthidae)

acta ethologica - Animal venom is composed of a complex mixture of protein-rich chemicals. Synthesis of animal venom incurs a high metabolic cost and is a prolonged process; consequently, animals...     

A new species of the rare buthid scorpion genus Lissothus Vachon, 1948 from Central Algeria (Scorpiones,Buthidae)

Taxonomic considerations are given for the genus Lissothus Vachon, 1948 (Scorpiones, Buthidae). Two species are currently known, Lissothus bernardi Vachon, 1948 from Libya and Lissothus occidentalis Vachon, 1950 from Mauritania. In this contribution, a new species, Lissothus chaambi sp. n., is described from the desert of Central Algeria. The new species is most closely related to L. bernardi. The geographical distribution of the genus is discussed.     

Wernerius inyoensis, an elusive new scorpion from the Inyo Mountains of California (Scorpiones, Vaejovidae)

A new scorpion species is described from the Inyo Mountains of California (USA). The presence of a strong subaculear spine, along with other characters, places the new species within Wernerius, an incredibly rare genus that until now consisted of only two species. Wernerius inyoensissp. n. can be most easily distinguished from the other members of the genus by smaller adult size, femur and pedipalp dimensions, and differences in hemispermatophore morphology. Previous studies have suggested that the elusive nature of this genus may be attributed to low densities and sporadic surface activity. Herein, we provide another hypothesis, that Wernerius are primarily subterranean. Mitochondrial sequence data are provided for the holotype.     

Ecological modeling and distribution analysis of digger scorpions: Odontobuthus doriae,Odonthubutus bidentatus (Scorpiones: Buthidae) and Scorpio maurus (Scorpiones: Scorpionidae) in Iran using the maximum entropy method

Prediction models are essential for the potential geographic distribution of scorpions, prevention of scorpion stings and diverse applications in conservation biology. There is limited information about habitat suitability and the factors affecting the distribution of Iranian digger scorpions. This study was undertaken to model the distribution of three types of digger scorpion in Iran, Odontobuthus doriae Thorell, Odonthubutus bidentatus Lourenco (Scorpiones: Buthidae) and Scorpio maurus Pocockin (Scorpiones: Scorpionidae), and investigate the factors affecting its distribution using the maximum entropy method. A total of 20 environmental and climate variables were used for modeling and evaluation of the ecological niche. The similarities and differences between the ecological overlap of the digger scorpions were evaluated using comparative environmental niche model (ENM Tools software). The results showed that the main factors for habitat suitability of O. doriae were soil type, mean temperature of the wettest quarter and slope. The variables for S. maurus were soil type, precipitation of the coldest quarter and slope. Annual temperature range, mean temperature of the driest quarter and land use had the greatest influence on the distribution of O. bidentatus. The ecological niches for O. doriae and O. bidentatus overlapped. The niche of these species differed from the niche of S. maurus. This approach could be helpful for the prediction of the potential distribution of three digger scorpion species and this model can be an effective for the promotion of health.