A potential explanation for the disjunct distributions of Western Mediterranean scorpions in the genus Euscorpius

 

The genus Euscorpius Thorell, 1876 (Euscorpiidae) is widespread and have a high diversity in the Western Mediterranean, including several islands with endemic species. An interesting case is Euscorpius oglasae Caporiacco, 1950 from the island of Montecristo. Based on morphological analysis it has been regarded as closely related to the species Euscorpius balearicus Caporiacco, 1950 in the Balearic islands. But how is this possible as the distance between these islands is very large? 

Javier Blasco-Aróstegui and co-workers have recently published molecular study where they try to explain the disjunct distributions of Western Mediterranean scorpions in the genus Euscorpius. The study confirms the previous conclusion that the two above mentioned species are indeed closely related, and it offers an explanation of how the initial diversification of E. oglasae happened in the Paleogene time period.

Abstract:
Aim: Small wood-scorpions (Euscorpius Thorell, 1876) are widespread across the Mediterranean forests, mountains, coastlines, and islands of Europe. Their ancient origins make them an excellent model system for reconstructing the complex biogeographical history of the western Palaearctic. The present study focused on the islands of the western Mediterranean, which are geologically dynamic and harbour many endemic and relictual taxa, and on the relationships among Euscorpius species inhabiting Montecristo and the Balearic Islands, in particular. Two hypotheses were tested: (1) long-distance dispersal from the Balearic Islands after Montecristo emerged following the HT/LP plutonic intrusion (8.4–7.2 Ma), and (2) a multi-phase scenario beginning with vicariance from the Balearic, Calabrian, Corsican, Sardinian and Sicilian (Ba-Ca- Co- Sa- Si) microplate fragmentation, followed by dispersal to Montecristo during the Messinian Salinity Crisis (5.97–5.33 Ma) or later Pliocene–Pleistocene sea-level regressions (3.6–0.2 Ma).
Location: Western Mediterranean islands of France, Spain, and Italy, including the Balearic Islands, Corsica, Sardinia, and the Tuscan Archipelago.
Time Periods: Eocene, Oligocene, Neogene, and Quaternary.
Taxon: Scorpiones: Euscorpiidae: Euscorpius Thorell, 1876: Euscorpius balearicus Caporiacco, 1950; Euscorpius canestrinii (Fanzago, 1872); Euscorpius concinnus (C.L. Koch, 1837); Euscorpius oglasae Caporiacco, 1950; Euscorpius sicanus (C.L. Koch, 1837).
Methods: Multi-locus phylogenies were inferred from 2815 base-pairs of concatenated DNA sequence of the nuclear region comprising 18S rDNA (partial) and the Internal Transcribed Spacer II, and mitochondrial 12S rDNA, 16S rDNA, and Cytochrome c Oxidase Subunit I loci using Maximum Likelihood, and divergence times estimated in a Bayesian framework with conservative fossil calibration constraints. Ancestral areas and biogeographical transitions were reconstructed using parametric models complemented by Principal Coordinates Analysis and Isolation-by- Distance tests to assess spatial genetic structure.
Results: Molecular clock dating and biogeographical analyses suggest initial diversification of E. oglasae occurred after break-up of the Ba-Ca- Co- Sa- Si microplate during the Oligocene (25.9 Ma), which transferred the lineage to the Corsica-Sardinia block. A likely passive dispersal event (i.e., transient lands, orogenies) towards Montecristo only occurred after its emergence (8.4–7.2 Ma), probably during the Messinian Salinity Crisis (5.97–5.33 Ma).

Reference:
Blasco-Aróstegui J, Isaia M, Barba-Montoya J, Tolve M, Roppo M, Prendini L. Ancient Divergence, Recent Island: Microplate Fragmentation and Dispersal Explain Disjunct Distributions of Western Mediterranean Scorpions. Journal of Biogeography. 2026;53(9). [Subscription required for full text]

Morphometrical variation in Buthus tunetanus from Tunisia

 

Interspesific variation in morphology between populations is not uncommon in many animal groups including scorpions. These variations may be responses to differences in habitats and/or climate. Sarra Hajri and co-workers have recently published a study of the morphometrical variations among populations of in Buthus tunetanus (Herbst, 1800) (Buthidae) in Tunisia.

Abstract:
Intraspecific variation among geographical separated samples has been documented in many scorpion species. This study focuses on morphometrical variation in Buthus tunetanus from Tunisia, in order to find morphometric features that could best distinguish different populations and highlight adaptative morphometric response. Thirteen morphometric variables were measured across 180 adult specimens. Statistical analysis, mainly based on discriminant factorial analysis, showed net intraspecific variability for males and females. Metasoma and telson size represent the most discriminant factor behind the recorded variation, which makes it a great candidate of natural selection. The morphology of this part is closely linked to the assault method and venom effectiveness which are controlled by each environment’s level of risk, the size, quality, and availability of prey. The Ouled Brahim’s and Oueslatia’s populations are the most discriminant ones when compared with other regions samples. The first population, belonging to a complex geological area, is distinguished by its sizeable segments. However, the second population, belonging to a semi-isolated area, is characterized by its dwarf segments. 

Reference:
Hajri S, Bahri L, Nouira S. Morphometrical Variation in Buthus tunetanus (Scorpiones: Buthidae) from Tunisia. Biology Bulletin. 2026;53:143. [Subscription required for full text]

Family Buthidae 

Influence of seasonality on habitat use and spatial distribution patterns of the buthid Physoctonus debilis in Brazil

 

The chose of habitat is important for scorpions for protection against predators and climate variations and for optimal access to prey. In some areas, climate seasonality has a strong effect on vegetation, and this may have an impact on the habitats chosen by scorpions.

André O. Silva-Júnior and co-workers have recently published a study on habitat use and spatial distribution patterns in a population of the tree-dwelling scorpion Physoctonus debilis (C. L. Koch, 1840) (Buthidae) across different seasonal periods in a Caatinga environment in Brazil.

The study demonstrates that the spatial distribution and habitat use of the tree-dwelling scorpion P. debilis are significantly influenced by seasonal changes, with variations observed among different sexes and developmental stages.

Abstract:
Habitat selection plays a crucial role in the survival of various animals, primarily due to their ability to identify suitable sites for development. In Caatinga regions, climate seasonality has a strong effect on vegetation, consequently influencing the occurrence and spatial distribution of diverse plant-associated organisms. The aim of this study was to analyse habitat use and spatial distribution patterns in a population of the tree-dwelling scorpion Physoctonus debilis (C. L. Koch, 1840) across different seasonal
periods in a Caatinga environment. Sampling was conducted during both dry and rainy seasons, each lasting 3 months, in northeastern Brazil. During each expedition, six plots measuring 30m× 30m and spaced 20m apart were sampled. In addition, the geographic coordinates of each specimen were recorded, and environmental metrics related to tree connectivity and isolation were measured. The results indicate that the population of P. debilis showed a higher occurrence during the dry season (158 individuals) than during the rainy season (105 individuals), with variations according to sex and developmental stage. Female occurrence was more frequently during the dry season, whereas immatures showed a higher occurrence during the rainy season. Our results also revealed spatial aggregation at short distances, with the intensity of aggregation varying among sexes, developmental stages, tree connectivity and climatic seasons. Overall, these results indicate that the spatial distribution of P. debilis is distance-dependent, with stronger spatial aggregation occurring at shorter distances.

Reference:
Silva-Júnior AO, Celante GL, Foerster SÍA, Feitosa MLB, Moura GJB, Lira AFA. Influence of Seasonality on Habitat use and Spatial Distribution Patterns of Tree-Dwelling Scorpion (Physoctonus debilis) in Brazilian Caatinga. New Zealand J Zool. 2026;53(3). [Open Access]

An updated catalogue of the scorpions of Paraguay with biogeographical information

 

Paul Smith and co-workers have recently published a updated review of the scorpion fauna of Paraguay. The country's scorpion fauna seems to consist of at least fifteen species in five genera and three families (Ananteridae, Bothriuridae and Buthidae). 

An identification key for the known species of Paraguay is included and the article also comments on some taxonomic problems and biogeography.

Abstract:
We review and map the current distribution of the Paraguayan scorpion fauna using a hierarchical system of reliability, differentiating specimens examined, specimens not examined and photographic records. One new species (Bothriurus sp.), two new national records (Brachistosternus simoneae and Ananteris mariaterezae), and nineteen new departmental distribution records are reported. The national fauna is concluded to be composed of at least fifteen species in five genera and three families, with one other species considered to be of hypothetical occurrence and a further two of probable occurrence. An illustrated key suitable for identifying Paraguayan material is included, and comments regarding taxonomy and systematic problems that remain to be resolved, together with proven and potential medical significance, are provided.

Reference:
Smith P, Borges A, Santacruz J, Owen M. Catalogue of the scorpions of Paraguay, with an illustrated key and biogeographical assessment (Arachnida: Scorpiones: Ananteridae, Bothriuridae, Buthidae). Invertzool. 2026;23:453–504. [Open Access]

Thanks to Victoria for informing me about this article! 

A new species of Scorpio from Iraq

 

Ersen Yagmur and co-workers have recently described a new species of Scorpio Linnaeus, 1758 (Scorpionidae) from southern Iraq.

Scorpio basraensis Yagmur, Makki & Najim, 2026

The genus Jordanius Afifeh, Yagmur, Al-Saraireh & Amr, 2024 (Scorpionidae) was synonymized with Scorpio Linnaeus, 1758 by Prendini, 2026. The authors of the current article reverse this decision and revalidate this taxa to genus status again. Please note that this only apply to the Prendini 2026 version of Scorpionidae in The Scorpion Files.

Abstract:
A new scorpion species, Scorpio basraensis sp. n., is described and illustrated from Basra Province, southern Iraq. Scorpio basraensis sp. n. is compared with all known species of the genus Scorpio Linnaeus, 1758 occurring in countries surrounding Iraq. The new species can be distinguished by the circular genital operculum in males and the cordiform genital operculum in females (not posteriorly elongated), a densely hirsute body, appendages and metasoma, a distinctly elongated telson vesicle, discrete granules on the external surface of the chela manus that are not flattened, and pectinal tooth counts of 11–13 in males and 9–11 in females. With the description of this species, the number of scorpion species known from Iraq increases to 22, whereas the number of recognized species in the genus Scorpio reaches 33 [According to Prendini, 2026 - Editor's addition].

Reference:
Yagmur EA, Makki JA, Najim SA. Scorpio basraensis sp. n. from southern Iraq (Scorpiones: Scorpionidae). Euscorpius. 2026(442):1–18. [Open Access]

Family Scorpionidae 

Maintaining Sand Scorpions in the laboratory

 

Douglas Gaffin is a very experienced scorpion researcher who has studied sense organs and sense physiology in scorpions for more than three decades. His main study animals have been the American Sand Scorpions Smeringurus mesaensis (Stahnke, 1957) and Paruroctonus utahensis (Williams, 1968) (Vaejovidae).

Douglas has now published an article where he shares his extensive experiences with keeping Paruroctonus utahensis in the laboratory. This will be very helpful for others who wants to keep this species under optimal conditions for research or hobby.

Abstract:
For over three decades, I have collected and maintained sand scorpions in my research laboratory. I have learned that these animals are not only easy to collect but also accepting of laboratory conditions. In this note, I followed a population of 34 sand scorpions collected from a sand field near Monahans, Texas, and housed under stable conditions in jars in my lab at the University of Oklahoma. I kept track of their feeding and watering schedules and noted their date of death. In the end, I generated a descriptive post-collection survivorship curve for this population. I hope that this account can help guide those interested in working with these exquisite animals and provide a baseline for comparing with other populations of collected animals held under laboratory conditions.

Reference:
Gaffin D. Lessons from Three Decades of Maintaining Sand Scorpions in the Laboratory: Husbandry and Survivorship of Paruroctonus utahensis. Arthropoda. 2026;4(3):15. [Open Access]

Thanks to Matt Simon for informing me about this article!

An update on the little known scorpion fauna of El Salvador

 

Luis F. de Armas and Enrique Maldonado have recently published an article with an update on the  little known scorpion fauna of El Salvador. At least six species from two families occur in this country. An identification key is included in the article.

Abstract:
The scorpions from Republic of El Salvador, Central America, have been poorly studied. The present work confirms the presence of at least six species in this country: Didymocentrus krausi Francke, 1978 (Diplocentridae), and five species belonging to the genus Centruroides Marx, 1899 (Buthidae), including the first records for Centruroides koesteri Kraepelin, 1911, Centruroides tapachulaensis Hoffmann, 1932, and an unidentified species of the thorellii species-group. Centruroides tapachulaensis had been confused with Centruroides edwardsii (Gervais, 1843), Centruroides gracilis (Latreille, 1804) and Centruroides margaritatus (Gervais, 1841). None of five nominal identified species are Salvadoran endemism. A taxonomical key is included for the identification of these six scorpion species. Most of the new records were made based on available data on the iNaturalist citizen science website.

Reference:
de Armas LF, Maldonado E. La casi desconocida escorpiofauna (Arachnida: Scorpiones) de El Salvador, América Central. Revista Nicaraguense de Entomologia. 2026(433):1–33. [Full text supplied by author]

Thanks to Victoria for informing me about this article!