Can analysis of venom be an important tool for species delimitation - a test case with Italian Euscorpius

Scorpion venom is a cocktail of different biological compounds, something that makes the venom of many species a potential treasure chest for medical and biochemical research. Scorpion venom may also have a potential utility in scorpion systematics. 

Javier Blasco-Arostegui and co-workers have recently published a study to see if scorpion venom may be a useful utility for species delimitation compared to other independent sources of taxonomic evidence. Venom mass fingerprinting (MFP) was used on the venom from 52 populations of eight Italian species of the scorpion genus Euscorpius Thorell, 1876, a genus known for many cryptic species.

This article is quite outside my competence, but the authors conclusion is that "MFPs appear highly effective for species discrimination across various levels of relatedness, DNA-based approaches currently provide higher resolution with limited taxon sampling. Venom MFPs may achieve comparable discriminatory power with broader taxon sampling and methodological optimization" (p. 16). In layman language, analysis of venom seem to be a good tool to supplement other DNA-based tools for identifying and separating taxa.

Abstract:
Scorpion venoms are complex mixtures of bioactive compounds including proteins, peptides and enzymes. Although venoms exhibit substantial intraspecific variation, some compounds appear to be species-specific, highlighting their potential as chemotaxonomic markers. Venom mass fingerprints (MFPs) derived from Matrix-Assisted Laser Desorption/Ionization Time-of-Flight (MALDI-TOF) Mass Spectrometry (MS) have been proposed as a means of delimiting species. However, their utility for species delimitation has rarely been evaluated against independent sources of taxonomic evidence. In the present study, the performance of MALDI-TOF MS-based venom peptide barcoding (mass ranges of m/z 800‒4500 and m/z 3000‒10,000) was assessed in 52 populations of eight Italian species of the scorpion genus Euscorpius Thorell, 1876, representing different levels of evolutionary divergence, by comparing venom MFPs with mitochondrial Cytochrome c Oxidase Subunit I (COI) DNA barcodes. Non-metric multidimensional scaling (NMDS) based on Jaccard distances of 52 venom MFPs (one per population) recovered seven distinct, statistically supported species clusters that were mostly congruent with analyses based on COI. Hierarchical clustering analyses using the intersection-based distances of the same MFPs consistently recovered the two major Euscorpius species complexes and revealed geographically structured subclades congruent with COI data. Venom profiles successfully discriminated among both closely and distantly related species in similarity-based analyses, recovering patterns broadly consistent with established phylogenetic hypotheses. Phylogenetic reconstruction with Maximum Likelihood, based solely on venom characters, obtained less resolution at deeper evolutionary levels, with lower nodal support and some incongruence with the topology obtained from the DNA sequences. The results demonstrate that venom MFPs constitute a useful source of data for species delimitation, particularly for resolving cryptic species complexes and morphologically conserved taxa, complementing morphological and DNA sequence data in integrative taxonomy. Broader taxon sampling, together with improved signal detection and character selection (filtering ion signals), may increase the utility of venom MFPs for phylogenetic analysis by increasing the number of phylogenetically informative characters.

Reference:
Blasco-Aróstegui J, Roppo M, Prendini L, Predel R. Venom mass fingerprints for species delimitation, reloaded: A test case with Italian scorpions (Euscorpius). Toxicon: X. 2026;32. [Open Access]

An updated overview of the scorpion fauna of Libya

 

Faraj Aboshaala and co-workers have recently published an updated overview of the species reported from Libya and their distribution patters in the country. 28 species in 12 genera from the families Buthidae, Euscorpiidae and Scorpionidae are reported.

Abstract:
Libya, one of the largest countries in North Africa, is characterized by a Mediterranean climate along its northern coast and an extensive hot desert climate across much of its territory. These environmental conditions provide suitable habitats for a diverse assemblage of scorpion species adapted to arid ecosystems. Despite this ecological suitability, the scorpion fauna of Libya remains inadequately documented, with previous studies largely restricted to individual species or limited geographic regions. Therefore, the present study aimed to update the inventory of Libyan scorpions through the examination of specimens collected from several localities between January 2020 and May 2025, combined with a comprehensive review of previously published records. The revised checklist comprises 28 scorpion species belonging to 12 genera and three families. The family Buthidae is the most diverse, encompassing 10 genera and 26 species, whereas the families Euscorpiidae and Scorpionidae are each represented by a single genus and species. A critical taxonomic reassessment resulted in the exclusion of three species—Androctonus crassicauda, Buthus occitanus, and Leiurus quinquestriatus—from the Libyan fauna. Endemic species account for 21.4% of the total diversity, with six species being restricted to Libya. Analysis of species distribution revealed that Androctonus amoreuxi and Androctonus australis are the most widespread species, each occurring in approximately 75% of the surveyed localities, whereas nine species were recorded from only a single site. At the regional level, Misurata and Tajura exhibited the highest species richness, each supporting eight scorpion species. Overall, scorpion diversity is particularly pronounced in northwestern Libya, where the convergence of Mediterranean and desert climatic conditions creates favorable habitats for a wide range of taxa. Nevertheless, the country’s scorpion fauna remains incompletely explored, highlighting the need for further systematic surveys and taxonomic investigations to achieve a comprehensive understanding of Libya’s scorpion biodiversity.

Reference:
Aboshaala F, Sadine SE, Ghaliow M, Stathi I, Badry A, Souilem Z, et al. First Exhaustive List and Distribution Pattern of Scorpions in Libya (Arachnida: Scorpiones). Annals of Arid Zone. 2026;65(3):227–38. [Open Access]

Thanks to Victoria for informing me about this article! 

Long-read mitogenomes reveal hidden control-region architecture in Smeringurus mesaensis with implications for vaejovid systematics

 

Matt Simon (https://instagram.com/crawly.creepy) made me recently aware of a new article from Matthew Graham and co-workers on the mitochondrial genome for the genus Smeringurus Haradon, 1983 (Vajeovidae). This stuff is way over my head and I had planned to not blog about it, but it turns out that the results have implications for vaejovid systematics and should be mentioned in the blog. 

Fortunately, I have been allowed to use Matt's review of the papers content and bring them to you in this post. And those interested can check out the article to see if you understand more than I do. :)

The researchers of the study set out to recover the first mitochondrial genome for the genus Smeringurus. However, one part of the genome was persistently difficult to recover. "What first appeared to be an incomplete or problematic portion of the genome gradually resolved...into a large and remarkably orderly tandem-repeat array in the control region" of the mitochondrial genome.

This is a new finding. It is significant because it shows "the control region as a structured and, potentially, an evolutionarily informative component of scorpion mitogenomes." The authors believe that this finding brings clarity to a difficult mitogenomic region that in the past was under-recognized because researchers were unable to make sense of it.

However, it's complicated. The researchers observe that this repeat array in the mitogenomic control region occurs in some other scorpion taxa, but it does not occur in all scorpion groups.

Lastly, the authors note that their study has implications for vaejovid systematics. "Within the limits of currently available mitogenomic sampling, S. mesaensis was recovered as sister to the remaining sampled vaejovids. That placement is notable because it is broadly consistent with earlier studies that also placed Smeringurus or Smeringurinae near the base of Vaejovidae."

However, the researchers note, prior work by Santibáñez-López et al. with phylogenomic data "recovered Smeringurinae...not as sister to the remaining vaejovids, but as a long branch nested within the family." That means the two techniques led to different systematic pictures. "That contrast suggests that the placement of Smeringurinae may remain sensitive to character sampling and analytical scale."

Abstract:
Repetitive regions of animal mitochondrial genomes are biologically informative but often difficult to assemble, raising the possibility that structured variation in mitochondrial control regions may be overlooked, especially in short-read datasets. We used Oxford Nanopore long-read sequencing to assemble five complete mitochondrial genomes of the dune scorpion Smeringurus mesaensis and resolve and validate the structure of the mitochondrial control region. In all five individuals, the 1598–1600 bp control region contained six complete 202 bp tandem repeats and one 92 bp terminal partial repeat. Mean control-region coverage ranged from 15.9× to 49.8×, with 10–33 reads spanning the 5′ repeat-array boundary, 14–25 spanning a central repeat junction, and three reads spanning the complete repeat array. Despite this repetitive architecture, the arrays were highly organized: repeats R2–R6 were identical within individuals, whereas R1 and the terminal partial repeat retained consistent positional differences. The 5′ non-repeat region showed significant local similarity to the control regions of Vaejovis mexicanus and V. smithi (72.8% and 69.6% identity), whereas the 202 bp repeat produced only short, nonsignificant matches. This pattern suggests that replication slippage and sequence homogenization have jointly shaped control-region evolution. A comparative survey of published scorpion mitogenomes further indicated that tandem repeats are more widespread and structurally diverse than generally reported. These results demonstrate the value of long reads for direct validation of repeat-rich mitochondrial architecture and highlight control-region structure as an underappreciated feature of scorpion mitogenome evolution.

Reference:
Graham MR, Santibáñez-López CE, Murdoch B. Long-Read Mitogenomes Reveal Hidden Control-Region Architecture in Smeringurus mesaensis and Overlooked Tandem Repeats in Scorpions. Arthropoda. 2026;4(4):16. [Open Access]

Thanks to Matt Simon for informing me about the article and for allowing me to use his review of it!

Family Vaejovidae

A new species of Compsobuthus from Pakistan

 

Muhammad Ishtiyaq and co-workers have recently published a new species of Compsobuthus Vachon, 1949 (Buthidae) from Pakistan.

Compsobuthus lakkianis Ishtiyaq, Adnan, Khan, Ali & Barahoei, 2026

The article includes an identification key for all known species in Compsobuthus in Pakistan. 

Abstract:
Members of the genus Compsobuthus, is distributed across the Arabian Peninsula, central Africa and the Indian subcontinent. The genus is represented in Pakistan by four documented species from the werneri group including Compsobuthus atrostriatus (Pocock, 1897), C. pakistanus Kovařík and Ahmed, 2007, C. sindicus Kovařík and Ahmed, 2011, C. rugosulus (Pocock, 1900). In this study, we describe a new species within the werneri group, Compsobuthus lakkiansis sp. nov., collected from a semi-sandy area in Lakki Marwat District, northeast Pakistan. Morphometric data were recorded and compared with those of closely related congeners. This discovery establishes the first record of the genus Compsobuthus in Lakki Marwat and raises the number of its species in Pakistan to five. This work serves as a critical baseline for future research on scorpion biodiversity and aids in developing effective conservation strategies.

Reference:
Ishtiyaq M, Adnan M, Ali A, Khan S, Barahoei H. Compsobuthus lakkiansis sp. nov. (Scorpiones: Buthidae), New Species from Pakistan. Pakistan Journal of Zoology. 2026;Online First Article. [Open Access]

Thanks to Victoria for informing me about this article!

Family Buthidae