Scorpion Species Research Articles

A Review on Scorpionism in Iran

Scorpions are one of the most important venomous animals in Iran. Their sting has more prevalence in the south and southwest areas. The aim of this study was to introduce their sting agent species in the country. Data were extracted by a mini review on scorpion stinging articles in Iran until early 2018 and then the sting agent species in each area were studied. Geographical and provincial distribution of each species also was provided. Twelve scorpion species are causative agents of sting. According to their deadly rate and clinical symptoms, some of them are considered the most dangerous venomous animals in Iran. Some death cases have been reported because of the sting of 3 species of Hemiscorpius lepturus, H. acanthocercus and Androctonus crassicauda. Remaining species have not deadly sting but because of their frequency, they encounter the individuals and cause the stinging. The highest number of sting agents is in Khuzestan, however Gilan and Mazandaran have the lowest frequency. Because of the high prevalence of sting agent species in that province, the necessity of providing control and prevention programs is very important.

Generation of a Broadly Cross-Neutralizing Antibody Fragment against Several Mexican Scorpion Venoms

The recombinant antibody fragments generated against the toxic components of scorpion venoms are considered a promising alternative for obtaining new antivenoms for therapy. Using directed evolution and site-directed mutagenesis, it was possible to generate a human single-chain antibody fragment with a broad cross-reactivity that retained recognition for its original antigen. This variant is the first antibody fragment that neutralizes the effect of an estimated 13 neurotoxins present in the venom of nine species of Mexican scorpions. This single antibody fragment showed the properties of a polyvalent antivenom. These results represent a significant advance in the development of new antivenoms against scorpion stings, since the number of components would be minimized due to their broad cross-neutralization capacity, while at the same time bypassing animal immunization.

Cophylogenetic analysis suggests cospeciation between the Scorpion Mycoplasma Clade symbionts and their hosts.

Scorpions are predator arachnids of ancient origin and worldwide distribution. Two scorpion species, Vaejovis smithi and Centruroides limpidus, were found to harbor two different Mollicutes phylotypes: a Scorpion Mycoplasma Clade (SMC) and Scorpion Group 1 (SG1). Here we investigated, using a targeted gene sequencing strategy, whether these Mollicutes were present in 23 scorpion morphospecies belonging to the Vaejovidae, Carboctonidae, Euscorpiidae, Diplocentridae, and Buthidae families. Our results revealed that SMC is found in a species-specific association with Vaejovidae and Buthidae, whereas SG1 is uniquely found in Vaejovidae. SMC and SG1 co-occur only in Vaejovis smithi where 43% of the individuals host both phylotypes. A phylogenetic analysis of Mollicutes 16S rRNA showed that SMC and SG1 constitute well-delineated phylotypes. Additionally, we found that SMC and scorpion phylogenies are significantly congruent, supporting the observation that a cospeciation process may have occurred. This study highlights the phylogenetic diversity of the scorpion associated Mollicutes through different species revealing a possible cospeciation pattern.

Toxicological and epidemiological studies of scorpion sting cases and morphological characterization of scorpions (Leiurusquin questriatus and Androctonus crassicauda) in Luxor, Egypt.

Scorpion envenomation is a common acute life threatening health problem in developing countries as Egypt. Scorpion venom is a complex structure composed of neurotoxic proteins, salts, acidic proteins, and organic compounds, thereby having of neurologic, cardiovascular, hematologic, and renal side effects, in addition to local effects such as redness, pain, burning, and swelling. The study consisted of two parts to describe demographic characteristics, toxicological manifestations of scorpion sting cases in Luxor, Egypt and morphological characterization of the commonest scorpion species in the studied community for easy rapid identification of scorpion species by doctors from the patient history to provide better choices of management. First part of the study include all cases of scorpion envenomation attending General Hospital of Esna, Luxor, Egypt during the period of scorpion activity 2017, demographic data was collected then cases were assessed for clinical manifestations, ECG, complications and deaths related to scorpion species. Second part: scorpions were collected from areas around patient housing for morphological description of their sense organs and venom apparatus by Scanning Electron Microscopy. A total of 110 cases of scorpion stings were reviewed, males 81 (72.9%) and females 30 (27.1%), with a mean age of 31.9 ± 17.9 years. Localized pain was the most frequent presenting complaint (89 80.2%), vomiting was the commonest clinical symptom (90.9%). All scorpion stings were due to the most endemic species in North Africa, Leiurusquinquestriatus & Androctonuscrassicauda. Death rate among cases was (5.5%) all were Abroug's Grade III. Cardiac dysrhythmia and subsequent pulmonary edema were the commonest cause of death. Clinical manifestations were more sever in Leiurus quinquestriatus stings while death rate was more in Androctonus crassicauda stings. The morphological characterization of the sense organs (eyes, pedipalps, pectines& sensory setae) and venom apparatus of the scorpions L. quinquestriatus & A. crassicauda were described by Scanning Electron Microscopy. Scorpion sting is an acute heath threating in Southern Egypt, Leiurus quinquestriatus & Androctonus crassicauda are most endemic scorpion species in Southern Egypt. More attention for scorpion envenomation in such subtropical hyper desert localities is required to eradicate toxic scorpion species and prevent possible causes of deaths.

A new species of Catalinia Soleglad et al., 2017 (Scorpiones: Vaejovidae) from southern California, USA

Herein we describe a new species of the vaejovid scorpion genus Catalinia Soleglad, Ayrey, Graham & Fet, 2017. It was collected in a single locality of the northwestern foothills of the Santa Ana Mountains. It is most closely related to both Catalinia andreas (Gertsch & Soleglad, 1972) and C. minima (Kraepelin, 1911), but is clearly distinguished by tegumentary sculpture, morphometric ratios and pectinal tooth counts. The new species is described and illustrated in detail, with some ecological data included; moreover, a minor correction is introduced to the diagnosis of the genus.

Seven new Alpine species of the genus Alpiscorpius Gantenbein et al., 1999, stat. n. (Scorpiones: Euscorpiidae)

Two subgenera of Euscorpius Thorell, 1876 (Scorpiones: Euscorpiidae) are elevated to the genus status: Alpiscorpius Gantenbein et al., 1999, stat. n. and Tetratrichobothrius Birula, 1917, stat. n. Seven new Alpine scorpion species are described and illustrated: Alpiscorpius delta sp. n. (Italy) from the “alpha group” (“germanus complex”); A. kappa sp. n. (Slovenia) and A. lambda sp. n. (Slovenia) from the “germanus group” (“germanus complex”); A. omega sp. n. (Slovenia), A. omikron sp. n. (Slovenia), A. sigma sp. n. (Italy, Slovenia), and A. ypsilon sp. n. (Austria, Slovenia) from the “gamma group” (“mingrelicus complex”). The taxonomic validity of these cryptic species is confirmed through cytogenetic and DNA analysis (Štundlová et al., 2019). Alpiscorpius beta (Di Caporiacco, 1950), comb. n., stat. n. (Italy, Switzerland) is restored from synonymy and elevated to species level within the “alpha group”. Euscorpius germanus marcuzzii Valle et al., 1971 (Italy), recently elevated to species level, is synonymized with Alpiscorpius germanus (C. L. Koch, 1837), comb. n. (which is found in Austria, Italy, and Switzerland but not in Slovenia). The genus Alpiscorpius currently includes 15 valid species (6 in “germanus complex” and 9 in “mingrelicus complex”). Many populations of Alpiscorpius spp. from the Balkan Peninsula, formerly listed under Euscorpius gamma or E. mingrelicus, remain unassigned.

Putative mating plugs of harvestmen (Opiliones, Laniatores)

In many species of scorpions (Order Scorpiones) and spiders (Order Araneae), mating plugs (gel-like or sclerotized) are deposited in the female reproductive tract, minimizing the possibilities of further matings. Although harvestmen (Order Opiliones) have direct sperm transfer via copulatory organs (penis or spermatopositor in the male and ovipositor in the female), prior studies of the reproductive anatomy of these arachnids have not reported the occurrence of these structures. With the aid of scanning electron microscopy, we observed distinct masses of amorphous, gel-like material in the distal openings of the ovipositors of six different specimens including representatives of the families Cosmetidae (Cynorta marginalis and Flirtea picta), Gonyleptidae (Discocyrtulus bresslaui and Geraeocormobius sylvarum), Kimulidae (Kimula sp.) and Metasarcidae (Metasarcus clavifemur). Dissection of one of these structures from a specimen of the cosmetid harvestman C. marginalis revealed a detailed endocast of the internal surfaces of the female reproductive tract. Considerable interspecific variation in the relative sizes and shapes (smooth and rough) of the amorphous gel-like structures were observed, but evidence of sclerotized components (i.e., parts of the male genitalia) was not found. The location and morphology of the gel-like structures are consistent with observations of mating plugs in other arachnids. The composition, source (male, female or both) and function of these amorphous gel-like structures (i.e. effective matting plug) requires additional study.

Biodiversity Species and Ecological Distribution of Scorpions in the City of Darmian, Southern Khorasan, Iran

Background and purpose: Scorpionism is a public health problem in Darmian City. This study was conducted to determine the biodiversity and faunistic of scorpions in order to discover the health preventive features of scorpion sting among the residents of these regions.Methods: A nightly and daily actively searching on distribution and biodiversity of scorpions was carried during April 2015 to March 2016 in Darmian, Iran.Results: A total of 685 scorpions including five species belonging to buthidae family were identified. The highest abundance was observed in warmer months, and Mesobuthus eupeus (54.5%) was the most abundant species. The researchers found a positive correlation between abundance and temperature and a negative correlation between abundance and humidity. The scorpions were observed with more nocturnal activity and were well-adapted with more abundance to the plain, rural, and outdoors environments. Regarding constancy index, all species except A. crassicauda were classified as constant species (C=100). There was no significant difference in the richness of scorpions in different time collections (day or night), geographical areas (plain or mountainous), regions collected (urban or rural), and places (indoors or outdoors). The Shannon and dominant indices were found to be not significantly different between mentioned sites except in time collection.Conclusions: Species composition of scorpions revealed that scorpions were constantly active throughout the year which can play an important role in sting events. So, familiarity of healthcare experts and indigenous people with existing species and their seasonal activities can largely reduce the risk of scorpion stings.

Five new scorpion species of genus Brachistosternus (Scorpiones: Bothriuridae) from the deserts of Chile and Peru, with comments about some poorly studied diagnostic characters of the genus.

Five new scorpion species of genus Brachistosternus of Chile and Peru are described. Brachistosternus gayi n. sp. is a high Andean species of north central Chile. Brachistosternus philippii n. sp. occurs near the coast of Antofagasta. Brachistosternus misti n. sp. occurs at intermediates altitudes of southern Peru. Brachistosternus contisuyu n. sp. occurs in Lomas formation in southern Peru. Brachistosternus anandrovestigia n. sp. occurs in coastal areas of southern Peru, and is the second known species of the genus without metasomal glands or androvestigia. Two diagnostic characters are discussed: the Internal Laminar Apophysis of the right hemispermatophore, and the sternum macrosetae.

Peptidomic characterization and bioactivity of Protoiurus kraepelini (Scorpiones: Iuridae) venom.

Protoiurus kraepelini is a scorpion species found in parts of Turkey and Greece. In this study, the peptide profile of its venom was determined for the first time. The electrophoretic profile of the crude venom showed a protein distribution from 2 to 130 kDa. MALDI-TOF MS analysis of the venom peptide fraction yielded 27 peptides between 1059 and 4623 Da in mass. Several ion channelblocking and antimicrobial peptides were identified by peptide mass fingerprinting analysis. Cytotoxic and antimicrobial effects of the venom were also demonstrated on Jurkat cells and Escherichia coli, respectively. As the first peptidomic characterization study on P. kraepelini venom, this report lays the foundation for detailed future studies that may lead to the discovery of novel bioactive peptides.

Biochemical characterization of the venom of Central American scorpion Didymocentrus krausi Francke, 1978 (Diplocentridae) and its toxic effects in vivo and in vitro

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 A2, 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.

Venom content and toxicity regeneration after venom gland depletion by electrostimulation in the scorpion Centruroides limpidus

The scorpion venom is a cocktail of many components. Its composition can exhibit a level of plasticity in response to different behavioral and environmental factors, leading to intraspecific variation. The toxicity and specificity of scorpion venoms appear to be taxon-dependent, due to a co-evolutionary interaction with prey and predators, which shaped the composition at the molecular level. The venom regeneration by the venom glands is an asynchronous process, in which particular components are expressed at different stages and at different rates. According to this, it can be reasonably assumed that the regeneration of toxicity in the venom is also asynchronous. In this work, we studied the toxicity regeneration dynamics by the scorpion Centruroides limpidus after full venom depletion by electrical stimulation. For this, we evaluated the toxicity of venom samples extracted at different days post depletion, against insects (crickets) and mammals (humans, by assessing the venom activity on the human voltage-dependent Na+ channel Nav1.6). The regeneration of toxicity against humans lagged behind that against crickets (13 vs 10 days, respectively). Thirteen days after depletion the venom seems to be replenished. Our results show asynchrony in the regeneration of species-specific toxic activity in the venom of Centruroides limpidus. The understanding of the venom regeneration kinetics for the different scorpion species will help to design venom extraction protocols that could maximize the yield and quality of the collected venoms.

Integration of phylogenomics and molecular modeling reveals lineage-specific diversification of toxins in scorpions.

Scorpions have evolved a variety of toxins with a plethora of biological targets, but characterizing their evolution has been limited by the lack of a comprehensive phylogenetic hypothesis of scorpion relationships grounded in modern, genome-scale datasets. Disagreements over scorpion higher-level systematics have also incurred challenges to previous interpretations of venom families as ancestral or derived. To redress these gaps, we assessed the phylogenomic relationships of scorpions using the most comprehensive taxonomic sampling to date. We surveyed genomic resources for the incidence of calcins (a type of calcium channel toxin), which were previously known only from 16 scorpion species. Here, we show that calcins are diverse, but phylogenetically restricted only to parvorder Iurida, one of the two basal branches of scorpions. The other branch of scorpions, Buthida, bear the related LKTx toxins (absent in Iurida), but lack calcins entirely. Analysis of sequences and molecular models demonstrates remarkable phylogenetic inertia within both calcins and LKTx genes. These results provide the first synapomorphies (shared derived traits) for the recently redefined clades Buthida and Iurida, constituting the only known case of such traits defined from the morphology of molecules.

Population dynamics of two troglobitic Troglorhopalurus (Scorpiones: Buthidae) scorpions from Brazil

Population dynamics studies raise relevant data to understanding ecological aspects and natural history of species as well as better conservation strategies. Using two scorpions species, Troglorhopalurus translucidus Lourenço, Baptista & Giupponi, 2004 and Troglorhopalurus lacrau (Lourenço & Pinto-da-Rocha, 1997) from Chapada Diamantina, Bahia state, Brazil, we estimate populacional parameters through mark and recapture methodology, and Jolly-Seber estimator. In addition, data on both species as sexual ratio, reproductive biology, growth, longevity, feeding habitats, and seasonality were analyzed in the caves and afterwards compared to other scorpion species as well as other arachnids. We captured and marked 82 specimens of T. translucidus and 65 specimens of T. lacrau. Population estimates were 361 ± 199 individuals to T. translucidus and 333 ± 252 to T. lacrau. Population estimates were considered high for the troglobitic scorpions when compared to subterranean arachnids or even with epigean species of scorpions. Both troglobitic scorpions featured remarkable differences in relation to epigean scorpions as higher longevity, longer reproductive period, slower growth. Besides T. translucidus showed marked seasonality with populational variations in rainy seasons in contrast to T. lacrau with populational stability. Suppl. material 1

Species Composition and Some Biological Features of Scorpions in Kaze-run District, Southern Iran

Scorpions have medical importance in the studied area with 2377 cases of envenoming during past six years. This study was the first to explore the scorpion species and dispersion in the Kazerun District during 2014-2015. The studied sites were selected based on different topographic conditions such as plain, foothill and mountainous which formed four geographical zones with three villages in each zone. The sampling was carried out twice each month throughout the year. Daytime collections were carried out using hand digging tools for moving stones and excavate the borrows, as well as night sampling, is done with the black light device. The coordinate of locations was recorded with a GPS. The collected specimens were maintained in 70% ethanol and identified using authorized keys. Overall, 800 scorpions were sampled from different parts of Kazerun District, bringing the species richness to 9 belonged to 3 families of Buthidae, Scorpionidae, and Hemiscorpionidae. The Mesobuthus eupeus (84.6%) was prominent vice versa M. caucasicus (0.1%) had lowest abundance. Other species comprised Compsobuthus matthiesseni (5.3%), Androctonus crassicauda (5.0%), Razianus zarudnyi (2.0%), Hemiscorpius lepturus (1.5%), Orthochirus sp (0.9%), Hottentotta zagrosensis (0.4%), and Scorpio maurus (0.3%). The seasonal activity of the scorpions showed a lower peak in Mar, with the main peaks in Aug for the dominant species. Mesobuthus caucasicus is recorded for the first time in the Fars Province, southern Iran. All the known dangerous scorpions, including H. lepturus, M. eupeus and A. crassicauda were revealed in the studied area.

Scorpion Venom Peptides as a Potential Source for Human Drug Candidates.

Scorpion venom is the most expensive and deadly venom with exciting medical prospects and having a potential as a source of drug candidates. A number of scorpion venom peptides have shown promising site specificity and are involved in the regulation of biological mechanisms. Due to the structural and functional specificity, the scorpion peptides are widely used for the development of specific drugs especially for the cardiovascular and other immune diseases. In this review, we summarize scorpion venom's biological activities such as antimicrobial, antiviral, anti-cancerous and in immune diseases. Evolutionary perspective of peptides derived from different scorpion venoms are also described in this review. The most significant venom peptides are; Ctriporin, Chlorotoxins (cltx), Neopladine I and II, Meucin 24, Meucin 25 and Hp 1090. The most recognized scorpion species with pharmaceutical activities are; Pandinus imperator, Chaerilustricostatus, Buthus martensii, Mesobuthus eupeus, Leiurus quinnquestriatus, Tityus discrepans and Heterometrus bengalensis. The role of peptides in cardiovascular events and in treating osteoporosis signifies their importance. The role of peptides against pathogens, skin infections, pain-relieving effects, anti-malarial and anti-viral effects are discussed in detail. We further, summarized the classification of scorpion peptides among different toxins, their evolutionary process and the pattern of scorpion venom resource analysis.

The protective effects and ameliorative potency of the haemolymph from the Saudi scorpion Androctonus crassicauda against the oxidative stress induced by its crude venom: A pharmacological study

Background: Envenomation from dangerous scorpions remains a horrible threat in many parts of the globe, especially the developed countries, reflecting a reliable cause of a lot of mortalities and morbidities for both children and adolescents; as the annual number of scorpion stings exceeds 1,200,000 resulting in approximately 3250 deaths. In Saudi Arabia, scorpions constitute an acute major medical problem with about 15, 000 average stung, yearly. The Saudi government has given high priority to the development of health care services to monitor scorpionism carefully, to manage its treatment protocols successfully, and to explain the pathophysiological effects of the venom. A wide variety to treat scorpionism was used, either singly or in combination. Mostly, treatment modalities include antivenom immunoglobulin (SAV) and chemical antidotes, with varying degrees of effectiveness and side effects, though the cons and the so expensive wholesale cost associated with SAV treatment. We are in bad need and warranty challenged to obtain safer, more effective, and not economically burdensome bioactive antivenins. Fourteen medically important scorpion species belonging to Buthidae have been identified in KSA. Although Androctonus crassicauda (A. c.) is an endemic and highly venomous scorpion in KSA, few studies were dealing with it. Objective: To evaluate the possible involvement of cellular oxidative reactions of the crude venom of the Saudi scorpion A. c., as the main cause of multiple organ dysfunctions, and how far scorpion haemolymph (SH) could be effective to protect and/or treat the envenomation-associated metabolic disorders. Materials and methods: Twenty-four adult male albino mice (25-32 g) were randomly divided into four groups; six in each. The controls; injected subcutaneously (SC) with 0.01 ml NaCl 0.9%/ kg BW, envenomed animals; receiving a single dose of crude venom of the Saudi scorpion A. c. (0.12 mg/kg BW; SC) and tested two hours post-injection, envenomed animals treated within 5 min. with an SC dose of 0.12 mg of SH/kg BW, and envenomed animals treated with the same dose and route with SH, two hours before scorpionism. Animals were dissected and different biochemical parameters and oxidative stress biomarkers were measured in serum, liver, and brain tissues. Results: Scorpion envenomation was accompanied by oxidative damage and hyperglycemia; which is causative for a generation of additional reactive oxygen species, and its subsequent metabolic disorders. Also, SH was predicted to significantly protect from and reverse all the cytotoxic manifestations following envenomation. Conclusion: The cytotoxic effects of crude venom of the Saudi scorpion A. crassicauda could be attributed to the generation of reactive oxygen species causing oxidative damage. The scorpion haemolymph can be used as a bioactive therapeutic agent to protect and treat the dysfunctions after envenomation, as it may contain novel molecule (s) to do this.

Environmental variation and seasonal changes as determinants of the spatial distribution of scorpions (Arachnida: Scorpiones) in Neotropical forests

Habitat selection and seasonal changes are key drivers of the population dynamics of many species. We analyzed how the environmental structure influences species establishment in an area by comparing microhabitat preference and functional richness of scorpions (Arachnida: Scorpiones) in wet (Atlantic forest) and semiarid (Caatinga) areas. Variations in superficial foraging activity and microhabitat colonization during dry and rainy seasons were evaluated as an indication of the climatic impact on population dynamics. We collected 12 scorpion species using ultraviolet light lamps. We found that differential patterns in spatial distribution were independent of forest type, and we provide evidence for partial niche partitioning among scorpion species based on age class and climatic conditions. Foraging activity was also seasonally influenced. Functional richness was higher in wet forests than in dry forests, whereas taxonomical richness exhibited an opposite pattern. We conclude that spatiotemporal resource partitioning and refuge sharing are important drivers of the population dynamics and spatial distribution of scorpion species in Neotropical forests.

Determination of median effective dose (ED50) of scorpion antivenom against scorpion envenomation using a newly developed formula.

BackgroundAbout 50 species of scorpions cause fatal scorpionism worldwide. Most of these are members of the Buthidae family, and include, among others, Mesobuthus eupeus, Androctonus crassicauda, Leiurus abdullahbayrami, Leiurus quinquestriatus, Tityus pachyurus and Androctonus australis. Because high doses of scorpion venom and antivenom can cause death and hypersensitive reactions, there is a need to develop a formula that can be used to calculate both lethal and effective doses for scorpion venom and antivenom, respectively, thereby obviating the need for laboratory experiments.MethodsIn view of this, a literature search was carried out with the aim of modifying the formula (LD50=ED503×Wa×10−4) for calculation of the median lethal dose (LD50) of scorpion venom and the ED50 of antivenom. The human equivalent dose (HED) formula was assessed for extrapolation of LD50 and ED50 from animals to human for comparison and relevance with the new formula.ResultsThe findings showed that the newly developed formula (LD50 = ED50 1/3 × W a × 10−4) yielded results that are very close to the reported values. Therefore, the newly developed and HED formulas can be used for calculation of LD50 and ED50 values for scorpion venom and antivenom, respectively.ConclusionThe new formula yielded better results than the HED formula, confirming its predictive validity, precision, and reliability, thereby obviating the need for rigorous experiments and justifying the principles of reduction, refinement, and replacement (3Rs).

Random or clumped: How litter dwelling scorpions are distributed in a fragment of Brazilian Atlantic forest

Knowledge of the patterns in the spatial distribution of species provides valuable information about the factors (resources and environment) that regulate the use of space by animals. Typically, the distribution of litter-dwelling scorpions in Atlantic forests is correlated with the structure of their microhabitats, although to better understand their natural history more studies on the patterns in their use of space are required. Therefore, we investigated the effect of rainfall on the patterns in the spatial distributions and population densities of two sympatric species of scorpion, Tityus (Archaeotityus) pusillus Pocock 1893 and Ananteris mauryi Lourenço 1982 in a fragment of Atlantic Forest in Brazil. The study was carried out during the dry (September) and rainy (June) months. We collected 501 individuals (268 T. (A.) pusillus and 233 A. mauryi) by actively searching at night using UV lanterns. We found that the spatial distribution and population density of T. (A.) pusillus, but not A. mauryi, were significantly affected by rainfall, with T. (A.) pusillus individuals showing a clumped pattern during the rainy month and random distribution in the dry month. We also found a different response in the population densities of the two species, with T. (A.) pusillus but not A. mauryi being affected by rainfall. Our results indicate that, although co-habiting in leaf litter, these species respond differently to rainfall, which affects their spatial distribution and abundance in this habitat.