Sex differences in morphology cause sex differences in stridulation in the buthid Jaguajir rochae

 

It is not that well known that scorpions can produce sound that probably is meant to function defensively as an anti-predator defense. The sound is often called stridulation, and in scorpions it can be produced by morphological structures on the chelicera, legs, cauda or pectines.

Welton Dionisio-da-Silva and co-workers have recently published a study on stridulation Jaguajir rochae (Borelli, 1910) (Buthidae) and any sex-differences in the morphology of the sound producing structures and the acoustic output.

They found that there were several differences in the morphology of the sound producing structures of the pectins between the sexes, and they also found that females produced longer and more intense signals while the males exhibited slightly higher peak frequencies.

Abstract:
Stridulation, acoustic communication produced by friction between specialized body structures, is a poorly studied antipredator mechanism. Scorpions may display multiple defensive responses, yet acoustic signaling in such defensive context remains poorly studied. Given the sexual dimorphism commonly observed in scorpion body size and pectines, the latter, which may be involved in sound production, could vary morphologically and result in acoustic differences. We hypothesized that (1) stridulatory apparatus of the scorpion Jaguajir rochae (Borelli, 1910) is sexually dimorphic, (2) sexual dimorphism in stridulatory structures affects acoustic parameters, and (3) stridulatory responses vary with stress, tested via (2.1) mechanical and (2.2) mechano-chemical stimulation. Sound-producing structures and acoustic parameters were measured and stridulation was tested under high/low mechanical stress and mechano-chemical stress, the latter using chemical cues from a mammalian predator. Females exhibited larger pectinal structures, whereas males showed a higher allometric ratio relative to body size. Stridulatory signals in J. rochae showed sexual differentiation primarily in delta time, dB Sound Pressure Level, and low frequency, as revealed by Principal Component Analysis, what explains 38.7% of acoustic variance. Females produced longer and more intense signals, whereas males exhibited slightly higher peak frequencies. Yet, the occurrence of stridulatory responses was similar across different stress treatments. These findings reveal that sexual dimorphism in stridulatory apparatus influences acoustic parameters and that stridulation in J. rochae can be triggered by mechanical stimulation, supporting its role as a defensive behavior. This study provides the first evidence of sex specific acoustic variation in scorpion stridulation and elucidates its function as an antipredator strategy.

Reference:
Dionisio-da-Silva W, Luna NMC, da Rocha PA, Willemart RH, daSilva MB. She Doesn't Whisper: Female-Prominent Stridulation Shaped by Morphology in a Buthid Scorpion and Insights on Its Function. Ethology. 2026;First published 25.05.26. [Open Access]

A review of the scorpion fauna of Syria and their distribution

 

Ersen Yagmur and Nazir Khalil have recently published a review of the scorpion fauna of Syria. The scorpion fauna of Syria has not been extensively investigated and the article present a historic overview of scientific reports previously published on this topic.

The article reports of 19 valid species and 2 subspecies from 11 genera in the families Buthidae, Diplocentridae, and Scorpionidae. Several previously reported taxa are removed from the list of Syrian scorpions. New locality reports are also listed for several species. 

In his mega-revision, Prendini (2026) raised Aegaeobuthus bishri (Lourenço, 2020) (Buthidae) to species status from sub-species status. This change has not yet been included in The Scorpion Files. Yagmur & Khalil have changed this taxa back to sub-species status as Aegaeobuthus nigrocinctus bishri (Lourenço, 2020) due to lack of justification by Prendini.

Abstract:
This study reviews and lists the scorpion fauna of Syria according to current scorpion systematics. Critical evaluation of published records confirms 19 valid species and 2 subspecies across 11 genera and 3 families (Buthidae, Diplocentridae, and Scorpionidae); erroneous records (21 species) have been excluded. New locality records are reported for Aegaeobuthus nigrocinctus (Ehrenberg, 1828), Buthacus tadmorensis (Simon, 1892), Compsobuthus matthiesseni (Birula, 1905), and Scorpio kruglovi Birula, 1910.  Additionally, Aegaeobuthus bishri (Lourenço, 2020) is herein treated as a subspecies of A. nigrocinctus.

Reference:
Yagmur EA, Khalil N. A Review on Scorpion (Arachnida: Scorpiones) Fauna of Syria with New Locality Records. Commagene Journal of Biology. 2026;10(1):211–25. [Open Access]

Thanks to Ersen for sending me their article! 

Do hot temperatures cause hot tempered scorpions?

 

Scorpions are dependent on the temperatures in its environment to regulate their body temperatures (being ectothermic) and they will probably also have an effect on scorpion behavior. Scorpions use their sting and venom in prey capture and defense. 

Zia Nisani and co-workers have recently published a study looking into if and how different temperatures impact stinging behavior in Hadurus obscurus Williams, 1970 (Hadruridae). They tested how different temperatures impacted the defensive sting response and also the prey capture behavior at three different temperatures.

Scorpions with higher temperatures were faster to sting and required less provocation before stinging. In addition, "hotter" scorpions were quicker to catch prey and succeed with it. A physiological explanation for these results is probably that increased temperatures will increase muscle performance and metabolic rate. 

Abstract:
Scorpions employ their stinging mechanism both for defense and predation, and being ectothermic, temperature influences their physiology and behavior. As such, we hypothesized that temperature both affects defensive stinging and prey-capture behavior in scorpions. We tested the effects of body temperature on these behaviors in the desert hairy scorpion, Hadrurus obscurus Williams, 1970. In the first experiment, scorpions were placed in temperature-controlled chambers with either high (26-28°C) or low (21-22°C) temperatures and probed to elicit a defensive sting. We recorded the reaction time and the number of probes needed to elicit a sting. In the second experiment, we observed and recorded prey capture behavior at three different temperatures (21, 29, and 33°C). Scorpions with higher body temperatures had faster defensive reaction times and required fewer probes to elicit a sting. Furthermore, at a higher temperature, scorpions were more likely to attempt and succeed in prey capture, but temperature did not seem to affect post-capture stinging behavior. As the temperature rises, increasing muscle performance and metabolic rate in ectotherms, it may cause an increase in prey capture attempts and faster reaction times, as observed in our experiment. These results support our hypothesis that both defensive and predatory behavior in H. obscurus is affected by temperature, allowing more insight into scorpion thermal ecology.

Reference:
Nisani Z, Bennett M, Enriquez A, Iniquez M, Martinez Rios E, Stone B. Effect of temperature on the defensive and predatory behavior of the scorpion Hadrurus obscurus (Scorpiones: Hadruridae). Euscorpius. 2026;2026(433):1–9. [Open Access]

A new species of Olivierus from Eastern Iran

 

Niloofar Hashemzahia and co-workers have recently published an article on the scorpion fauna of Nehbandan County, Eastern Iran. I new species of Olivierus Farzanpay, 1987 (Buthidae) is described.

Olivierus simabina Barahoei, 2026

Abstract:
Given the lack of research on scorpion species in South Khorasan province, this study is deemed necessary. Understanding the scorpion fauna and its seasonal occurrence is essential for effectively preventing and treating scorpion stings. Sampling was done evenly using an ultraviolet light at night or direct observation during the day. In this study, 141 specimens were collected from different parts of Nehbandan county. Five species belonging to five genera of the Buthidae were collected and identified, the first four being Androctonus orientalis (Birula), Mesobuthus rakhshanii Barahoei, Odontobuthus tirgari Mirshamsi et al. and Sassanidotus gracilis (Birula). Olivierus simabina Barahoei sp. n. was also described, and its record was added to the scorpion fauna of Iran. No other species except for O. tirgari has been recorded from Nehbandan. Sassanidotus gracilis is a new report for the fauna of the South Khorasan province.

Reference:
Hashemzahi N, Ravan S, Barahoei H. New species and faunal records of the scorpions of Nehbandan County, eastern Iran (Scorpiones: Buthidae). Journal of Natural History. 2026;60(25-28):1431–46. [Subscription required for full text]

Family Buthidae 

Two new chactid species from Northernmost Brazilian Amazon

 

Andre Lira has co-workers have recently published an article describing two new species in the family Chactidae from the Northernmost Brazilian Amazon.

Brotheas cernii Lira, Gonzalez-Santillan, Santos-da-Silva, Brescovit & Pucca, 2026

Cayooca puchus Lira, Gonzalez-Santillan, Santos-da-Silva, Brescovit & Pucca, 2026

The genus Cayooca Gonzalez-Sponga, 1996 has been synonymized with Broteochactas Pocock, 1893. In the recent mega-revision of scorpion taxonomy, Prendini, 2026 resurrected this genus. As previously mentioned, I'm in the process of mapping all changed made in the Prendini paper and decide how to include these in The Scorpion Files. However, because a new species has been described in Cayooca, I have chosen to include this genus as valid in The Scorpion Files. A consequence of this is that Cayooca venezuelensis Gonzalez-Sponga, 1996 is returned to its original genus from Broteochactas Pocock, 1893.

Abstract:
Amid an ongoing environmental crisis marked by high deforestation rates in the Brazilian Amazon, two new species of chactid scorpions are herein described. Cayooca puchus sp. n. is described from an inselberg in the municipality of Mucajaí, state of Roraima, northern Brazilian Amazon. The new species resembles Cayooca venezuelensis but differs by denser body granulation and strongly costate, scattered granular ventromedian and ventral prosubmedian carinae. Brotheas cernii sp. n., described from the same locality, resembles Brotheas granulatus and B. subgranulatus but differs by smaller body size, granular ventral carinae on metasomal segment I, strongly granular pedipalp chelae, and spinoid granules on ventral metasomal carinae of segments III–V. These findings reinforce the Amazon as a major center of biodiversity and highlight the likelihood that numerous species remain undescribed.

Reference:
Lira AFA, González-Santillán E, Santos-da-Silva AP, Brescovit AD, Melo-dos-Santos G, Rocha AM, et al. Two New Species of Scorpions (Scorpiones: Chactidae) from Northernmost Brazilian Amazon. Diversity. 2026;18(6):345. [Open Access]

Thanks to Andre for sending me their article!

Family Chactidae 

A detailed description of the external morphology of Hottentotta saulcyi

 

 Niyazi Deniz and Melek Erdek have recently published a study of the external morphology of the male and female Hottentotta saulcyi (Simon, 1880) (Buthidae). Functional morphological implications are also discussed.

Abstract:
The comparative external morphological structures were surveyed on male and female Hottentotta saulcyi (Simon, 1880) in detail with scanning electron microscope (SEM). The constellation arrays on chelae, peg sensilla on the pectinal organ, aculear peg sensilla on aculeus part of telson, femoral cluster setae and trichobothria on chelae, and the other sensillar structures (sensilla trichodea, sensilla chaetica, slit sensilla) and epicuticular patterns on chelicerae, legs, and their functional morphologies were assessed in light of habitat and climatic preferences of both sexes of the species. This study constitutes the first comprehensive investigation of the external morphology of H. saulcyi.

Reference:
Deniz N, Erdek M. An evaluation of external morphology of Hottentotta saulcyi (Simon, 1880) (Scorpiones: Buthidae). Serket. 2026;21(2):147–57. [Open Access]

Thanks to Hisham  El-Hennaway for sharing the full text of this article with me!  

A new species of Compsobuthus from Iraq

 

Frantisek Kovarik and Frantisek Stahlavsky have recently published the description of a new species of Compsobuthus Vachon, 1949 (Buthidae) from Iraq.

Compsobuthus hadeki Kovarik & Stahlavsky, 2026

Abstract:
A new species, Compsobuthus hadeki sp. n. from Iraq is described and fully complemented with color photographs and compared with morphologically the most similar species, C. matthiesseni (Birula, 1905). The two species can be unequivocally separated by the following morphological features: in C. hadeki sp. n., movable finger of pedipalp bears 9 rows of granules; telson with aculeus shorter than vesicle, and metasoma III with 10 carinae. Cytogenetic analysis was performed, revealing a diploid chromosome count of 22 in C. hadeki sp. n.

Reference:
Kovarik F, Stahlavsky F. Compsobuthus hadeki sp. n. from Iraq (Scorpiones, Buthidae). Euscorpius. 2026(432):1–8. [Open Access]

Family Buthidae