Early Devonian scorpions also had pectines

 

Pectines are one of the body structures that are unique for scorpions. This comb-like structure is found on the underside of the opisthosoma of scorpions and is a sensory organ for detecting both chemical and mechanical stimuli. 

In a recent short note, Jason Dunlop and co-workers report about a cuticle fragment from a pectinal tooth from a Early Devonian scorpion. This fossil indicates that some scorpions had developed anatomically modern pectinal teeth at least 395 million years ago and that they probably had a similar function as the pectines in today's scorpions.

Abstract:
A cuticle fragment found in an Early Devonian (Emsian) macerate from the Strathpeffer–Struie outlier in the Northern Highlands of Scotland represents the isolated pectinal tooth of a scorpion. This remarkable find includes a distinctive field of small projections in rounded sockets consistent with the peg sensilla of extant scorpions. This is the oldest evidence for the presence of these characteristic sensory organs, which in modern scorpions play an important role in chemo- and mechanoreception. The fossil indicates that some scorpions had developed anatomically modern pectinal teeth at least 395 million years ago, suggesting that the pectines of these early scorpions played a similar role, physiologically and behaviorally, to those of living species.

Reference:
Dunlop JA, Wellman CH, Prendini L, Shear WA. A pectinal tooth with peg sensilla from an Early Devonian scorpion. The Journal of Arachnology. 2023;51(3):255-7, 3. [Subscription required for full text]

Thanks to Matt Simon for informing me about this article!

Venom of two scorpion species can be used in developing drugs against the tropical disease Leishmaniasis

 

Scorpions and their venom is a goldmine when it comes to finding molecules and toxins that can be used to develop medicines and other useful products for humans. One of the most known examples is Chlorotoxin, a peptid found in the venom of Leiurus quinquestriatus (Ehrenberg, 1828) (Buthidae), which has been used in the development of methods for the treatment and diagnosis of several types of cancer. There is a huge amount of research on scorpion venom going on these days.

D. B. Pereiraa and co-workers recently published a study where they showed that the venoms of Brotheas amazonicus Lourenço, 1988 (Chactidae) and Tityus metuendus Pocock, 1897 (Buthidae) can be used in the fight against the tropical disease Leishmaniasis (a zonosis caused by parasites of the Trypanosomatida genus Leishmania). The authors hope that components in the venom can be used in the development of new drugs against this serious tropical disease.

Abstract:
Leishmaniasis is a vector-transmitted zoonosis caused by different species of the genus Leishmania, with a wide clinical spectrum. It is a public health problem aggravated by a series of limitations regarding treatment. In the search for new therapeutic alternatives, scorpion venoms are a source of multifunctional molecules that act against the natural resistance of pathogens. This work evaluated the antileishmanial potential of Brotheas amazonicus and Tityus metuendus venoms against the promastigote forms of Leishmania amazonensis e Leishmania guyanensis. The venoms of B. amazonicus and T. metuendus were evaluated for their constituents using Fourier Transform Infrared (FTIR). Growth inhibition and death of promastigotes were evaluated in the presence of diferente crude venom concentrations (100 μg/mL, 50 μg/mL, 10 μg/mL, 1 μg/mL) after one hour of incubation at 25 °C. The FTIR spectra of both venoms exhibited bands in approximate regions, revealing that both exhibit similar functional groups. Crude venom from both scorpion species showed similar or superior leishmanicidal effects to the standart drug N-methylglucamine antimoniate. At the highest concentration of 100 μg/mL, cultures of L. guyanensis treated with the venom of B. amazonicus showed the highest mortality percentages, above 28%, while T. metuendus venom showed the highest activity against L. amazonensis, with mortality above 7%. This preliminar study demonstrates that B. amazonicus and T. metuendus venoms can be important tools in the search for new drugs Against leishmaniasis. Next step involves evaluating the activity against the amastigote forms and purifying the venom proteins in order to identify the best anti-leishmania candidates.

Reference:
Pereira D, Martins J, Oliveira M, Lima-Júnior R, Rocha L, Andrade S, Procópio R. Leishmanicidal activity of the venoms of the Scorpions Brotheas amazonicus and Tityus metuendus. Brazilian Journal of Biology. 2023;83:e276872. [Open Access]

Thanks to Jonas Martin for sending me their article!

Detailed morphology description and images of the medical important scorpion Hemiscorpius lepturus

 

Fenik Sherzad Hussen and co-workers recently published a study with a detailed description of the morphology of Hemiscorpius lepturus Peters, 1861 (Hemiscorpiidae). The article also includes detailed morphological images taken by a scanning electron microscope (SEM). 

Abstract:
Hemiscorpius lepturus Peters, 1861 is redefined in both sexes. The detailed external morphologies of chelae, pectinal organs, chelicerae, telsons, and legs I–IV were surveyed with the scanning electron microscope (SEM) in both sexes of H. lepturus for the first time. The constellation arrays, batlike shaped peg sensilla, trichobothria, and the other sensillar and epicuticular structures were described, and their functional morphologies were interpreted considering the species’ habitat and other climatic preferences. The constellation arrays, basiconic sensilla, function as a chemoreceptor (hygro-reception or/and thermo-reception) by its location on the pedipalp in the habitat. The shape of the peg sensilla is remarkably bat-like in both sexes and this shape has not been observed or recorded in any scorpion species, functioning as mechanoreception and contact chemoreception. There are three slit sensilla as single slit, dual and triple slit sensilla on I–IV walking legs, being mechanoreceptors as proprioceptors detecting strain and substrate vibrations during movement. Isolated single slit sensillum was recorded on the chelicerae surface of a scorpion species for the first time.

Reference:
Hussen FS, Erdek M, Yagmur EA. External morphology of Hemiscorpius lepturus Peters, 1861 (Scorpiones: Hemiscorpiidae). Arthropoda Selecta. 2023;32(4):419-37. [Open Access]

Thanks to Ersen for sending me their article!

A review of teratological abnormalities in scorpions

 

Teratology is the study of physiological development abnormalities of in organisms during their life span (Wikipedia, 2023). Teratological abnormalities in scorpions are known to occur in most families, involving many different body parts. 

Danniella Sherwood and Luis F. de Armas have recently published several new teratological findings and also a review of the literature on morphological anomalies in scorpions.

Abstract:
Whilst undertaking curation in the collections of the Natural History Museum, London, the senior author came across a jar of scorpions marked ‘scorpions with curled feet’. Further investigation showed this jar was full of scorpions with teratological anatomy. We hereby document and illustrate all of the specimens and discuss their respective anomalies. Furthermore, a comprehensive checklist of the literature on anomalies in scorpions, including giving the life stage and sex where known, is compiled for the benefit of future workers.

Reference:
Sherwood D, de Armas LF. On some teratological scorpions in the Natural History Museum, London and checklist of the scorpiological literature on morphological anomalies (Arachnida: Scorpiones). Euscorpius. 2023;2023(381):1-20. [Open Access]

Thanks to Danniella for informing me about their new article!

Venom composition in the medical important scorpion Leiurus abdullahbayrami from The Middle East

 

The 23 species in the genus Leiurus Ehrenberg, 1828 (Buthidae) have the most potent venom of all scorpions and posing a medical threat to humans in their area of distribution. Knowledge of the venom composition and potency of the different species is important for correct treatment and the use of antivenom.

Adolfo Borges and Bruno Lomonte have recently published a study of the venom composition of Leiurus abdullahbayrami Yagmur, Koc & Kunt, 2009, distributed in Turkey, Syria, and Lebanon. This species have been involved in serious envenomations and this study confirms the potency of its venom. 

The study also found that the venom composition in Leiurus abdullahbayrami and other species vary and more research on this potential interspecific variation is necessary to decide whether a species-specific antivenom is necessary for sting cases involving this species.

Abstract:
The scorpion Leiurus abdullahbayrami has been associated with severe/lethal envenomings throughout the Levant region of the Middle East, encompassing Turkey, Syria, and Lebanon, and only scarce information is available on its venom composition, activity, and antigenicity. We report on the composition of L. abdullahbayrami venom collected from Lebanese specimens using nESI-MS/MS, MALDI-TOF MS, SDS-PAGE and RP-HPLC. Venom lethality, through LD50 determination in mice (intraperitoneal), was also assessed (0.75 (0.16–1.09) mg/kg), confirming L.abdullahbayrami venom vertebrate toxicity. Fifty-four peaks were detected using RP-HPLC, half of which eluted in the gradient region between 20 and 40% acetonitrile. In reducing SDS-PAGE, most predominant components were <10 kDa, with minor components at higher molecular masses of 24.4, 43.1, and 48.9 kDa. Venom mass fingerprint by MALDI-TOF detected 21 components within the 1000–12,000 m/z range. Whole venom ‘shotgun’ bottom-up nLC-MS/MS approach, combined with in-gel tryptic digestion of SDS-PAGE bands, identified at least 113 different components belonging to 15 venom families and uncharacterized proteins, with ion channel-active components (K+ channel toxins (28); Na+ channel toxins (42); Cl􀀀 channel toxins (4); Ca+ toxins (2)) being predominant. A single match for a L. adbullahbayrami NaTx was found in the UniProt database with other congeneric species, toxin h3.1 from Leiurus hebraeus, suggesting this might be an indication of venom divergence within Leiurus, eventhough this warrants further investigation involving venom proteomics and transcriptomics of relevant species. Considering such potential interspecific venom variation, future work should address whether preparation of a specific anti-L. abdullahbayrami antivenom is justified.

Reference:
Borges A, Lomonte B. Venomics of Leiurus abdullahbayrami, the most lethal scorpion in the Levant region of the Middle East. Toxicon. 2024;237:107548. [Subscription required for full text]

Thanks to Luis A. Roque for informing me about this article!

A new study of the Isometrus in India with a description of five new species

 

Shubhankar Deshpande and co-workers have recently published a major study of the Isometrus Ehrenberg, 1828 (Buthidae) in India. Five new species are described from the southern parts of the country.

NB! The Year for these was corrected 18.12.23 to 2024 as the article is labeled 2024. Thanks to Gerard Dupre for noticing!

 Isometrus adviteeya Deshpande, Gowande, Dandekar, Joshi, Bastawade & Sulakhe, 2024

Isometrus anamalaiensis Deshpande, Gowande, Dandekar, Joshi, Bastawade & Sulakhe, 2024

Isometrus lithophilis Deshpande, Gowande, Dandekar, Joshi, Bastawade & Sulakhe, 2024

Isometrus palani Deshpande, Gowande, Dandekar, Joshi, Bastawade & Sulakhe, 2024

Isometrus thenmala Deshpande, Gowande, Dandekar, Joshi, Bastawade & Sulakhe, 2024

In addition, the following taxonomical changes have been made:

Odontobuthus atherii (Amir & Kamaluddin, 2008) (New combination). Previsously in the genus Reddyanus Vachon, 1972.

Odontobuthus liaqatii (Amir & Kamaluddin, 2008) (New combination). Previsously in the genus Isometrus Ehrenberg, 1828.

Isometrus formosus Pocock, 1893 is declared as nomen dubium.

The article has an indedification key for the genus in India and also descriptions and habitat information and pictures.

Abstract:
The Western and Eastern Ghats of the Peninsular India are known for their high biological diversity, which is shaped due to various geological barriers and environmental parameters. Scorpion diversity in Peninsular India remains poorly known thereby warranting a need to undertake rigorous arachnological surveys. In our continued effort to discover scorpion lineages hitherto unknown to science, we describe five new species of the genus Isometrus Ehrenberg, 1828 which were obtained from southern India, and discuss morphological, molecular and ecological discordance within this genus. The validity of Reddyanus atherii Amir and Kamaluddin, 2008, Isometrus liaqatii Amir and Kamaluddin, 2008 and Isometrus formosus Pocock, 1894 is also commented upon, with implications to propose taxonomic changes within the genus.

Reference:
Deshpande S, Gowande G, Dandekar N, Joshi M, Bastawade D, Sulakhe S. A baffling case of morphological, molecular and ecological discordance in Isometrus Ehrenberg, 1828 (Scorpiones: Buthidae) with the description of five new species from southern India. Zoologischer Anzeiger. 2024;308:71-98. [Subscription required for full text]

Family Buthidae

Scorpion assemblages in threatened Brazilian forests

 

Understanding the scorpion biodiversity, distribution, species composition in time and space between and within habitats is important, especially in a time were many scorpion habitats and ecosystems are threatened, both by human impact and climate changes.  

André Lira and co-workers have recently published a study on the role of environmental factors in explaining beta-diversity patterns in threatened Brazilian forests. André (personal communication) kindly explained to me what bet-diversity is: "Basically, beta diversity addresses the change in species composition between one place and another. In my article, I used two components of beta diversity, species replacement and differences in species richness, each of which gives an answer about how the composition of a given community is structured."

The main conclusion of the study is that the scorpion species composition does not vary in a consistent way between different forest types investigated. See abstract and article for more details.

Abstract:
1. A systematic understanding of the variation in species composition across time and space is urgently needed to protect threatened Brazilian forests.

2. This study has disentangled the among-site variation in beta diversity among scorpion assemblages from the Caatinga and Atlantic Forest. We calculated the relative contribution of species replacement and differences in species richness in explaining the beta diversity in each forest, correlating such metrics with environmental characteristics. Finally, we estimated the relative site-specific contribution to identify potential environmental drivers determining unique combinations of species composition.

3. The average among-site dissimilarity in scorpion assemblages was higher in the Caatinga than that in the Atlantic Forest. The differences in species composition among Caatinga sites were mainly due to the spatial replacement of species. Differences in species richness at the local scale explained most of the variation in species composition among Atlantic Forest sites.

4. Environmental variables related to topography and land use partially explained the variation in among-site dissimilarity, species replacement, differences in species richness and the ecological uniqueness in terms of species composition in the Caatinga. Environmental variables describing topography and land use were also important in explaining differences in species richness and local contributions to the beta diversity among Atlantic Forest sites. The relative site-specific contribution to beta diversity was higher in Caatinga sites located in ecotonal zones and Atlantic Forest sites situated within conservation reserves.

5. Using scorpions as biological models, we have demonstrated that the species composition does not vary in a consistent way between different forest types.

Reference:
de Araujo Lira AF, de Moura GJB, Foerster SÍA. Scorpion assemblages in threatened Brazilian forests: The role of environmental factors in explaining beta‐diversity patterns. Insect Conservation and Diversity. 2023;First published 15 November 2023. [Sunscription required for full text]

Thanks to André for sending me their article and updating my ecology knowledge.

A new species of Paruroctonus Werner, 1934 from California’s San Joaquin Valley, USA

 

Prakrit Jain and co-workers recently described a new species of Paruroctonus Werner, 1934 (Vaejovidae) from lowland, alkali-sink habitats in the Tulare Basin in California, USA.

Paruroctonus tulare Jain, Forbes, Gorneau & Esposito, 2023

The article provides detailed information about morphology, distribution, ecology and conservational status. Regarding the latter, this species inhabits a specialized habitat and its status is probably impacted by human activities like land conversion for agriculture and urban development. In addition, invasive European grasses seem to negatively impact on the species distribution and numbers.

Abstract:
Herein a new species of Paruroctonus Werner, 1934 is described from alkali-sink habitats in the San Joaquin Desert of central California, Paruroctonus tulare sp. nov. It can be differentiated from other Paruroctonus by a combination of morphological features including scalloped pedipalp fingers in males, specific setal counts and morphometric ratios, and specific patterns of fuscous pigmentation. It also inhabits a unique distribution allopatric with all other Paruroctonus species except P. variabilis Hjelle, 1982. Photographs of a large series of live P. tulare sp. nov. from across their range and detailed images of several morphological features are provided, their distribution is modeled, a haplotype network is presented, and details about their habitat, ecology, and conservation are discussed.

Reference:
Jain P, Forbes H, Gorneau JA, Esposito LA. A new species of alkali-sink Paruroctonus Werner, 1934 (Scorpiones, Vaejovidae) from California’s San Joaquin Valley. ZooKeys. 2023(1185):199-239. [Open Access]

Thanks to Matt Simon for informing me about the new species.

Family Vaejovidae