29 June, 2022

New fossil scorpion taxa

 


I have learned about two new articles on scorpion fossil taxa. The Scorpion Files only includes extant taxa, but here are the new fossil taxa reported in the two articles cited below.

New family:

Protochactidae Lourenço, Magnani & Stockar, 2022

New genus:

Protochactas Lourenço, Magnani & Stockar, 2022

New species:

Protochactas furreri Lourenço, Magnani & Stockar, 2022 (Limestone, Southern Alps)

Chaerilobuthus brandti Lourenço, 2022 (Amber, Myanmar)

Abstract:

Paper 1:
One new family, genus, and species of fossil scorpion are described from the Meride Limestone (Ladinian, Middle Triassic) of Monte San Giorgio (Southern Alps). This new discovery brings further evidence for the recovery of terrestrial forms of scorpions, following the Late-Permian mass extinction. The new fossil family proposed at present can, once again, be classified within extant familial groups; in this case the superfamily Chactoidea (sensu Lourenço). These results reinforce the proposition that modern scorpions may belong to lineages present at least for 240 Myr.

Paper 2:
A further new species of fossil scorpion belonging to the genus Chaerilobuthus Lourenço & Beigel, 2011 is described from Early Cretaceous Burmite. Chaerilobuthus brandti Lourenço sp. n., is the 12th species to be described for this genus confirming its speciose character. The new species equally shows quite distinct characters when compared to the previous known species, confirming therefore the existence of an important morphological variability within Chaerilobuthus.

References:

Paper 1:
Magnani F, Stockar R, Lourenço WR. A new family, genus and species of fossil scorpion from the Meride Limestone (Middle Triassic) of Monte San Giorgio (Switzerland). Faunitaxys. 2022;10(24):1-7. [Open Access]

Paper 2:
Lourenço WR, Velten J. The remarkable variability of the genus Chaerilobuthus Lourenço & Beigel, 2011 (Scorpiones: Chaerilobuthidae) and description of a new species from Early Cretaceous Burmite. Faunitaxys. 2022;10(10):1-6. [Open Access]

Thanks to Nicolas Machiavel for informing me about these two articles!

How does Paruroctonus utahensis find its way home

 


Finding the way home is an important skill for burrowing scorpions like Paruroctonus utahensis (Williams, 1968) (Vaejovidae). There have been some indications that scorpions use a view-based navigational process termed "Navigation by Scene Familiarity", which has been seen in bees and ants. Douglas Gaffin and co-workers have recently published a study where they investigate if scorpions may be guided by tastes and touches acquired via their mid-ventral pectines, instead of or in addition to vision.

The authors have named this form of homing "The Navigation by Chemotextural Familiarity Hypothesis (NCFH)". In their study they find evidence of learning walks during burrowing in Paruroctonus utahensis and they conclude that these putative learning walks, together with recently reported path integration in scorpions, may provide the crucial home-directed information requisite for NCFH. 

Abstract:
The navigation by chemo-textural familiarity hypothesis (NCFH) suggests that scorpions use their midventral pectines to gather
chemical and textural information near their burrows and use this information as they subsequently return home. For NCFH to be viable, animals must somehow acquire home-directed ‘tastes’ of the substrate, such as through path integration (PI) and/or learning walks. We conducted laboratory behavioral trials using desert grassland scorpions (Paruroctonus utahensis). Animals reliably formed burrows in small mounds of sand we provided in the middle of circular, sandlined behavioral arenas. We processed overnight infrared video recordings with a MATLAB script that tracked animal movements at 1–2 s intervals. In all, we analyzed the movements of 23 animals, representing nearly 1500 h of video recording. We found that once animals established their home burrows, they immediately made one to several short, looping excursions away from and back to their burrows before walking greater distances. We also observed similar excursions when animals made burrows in level sand in the middle of the arena (i.e. no mound provided). These putative learning walks, together with recently reported PI in scorpions, may provide the crucial home-directed information requisite for NCFH.

Reference:
Gaffin DD, Munoz MG, Hoefnagels MH. Evidence of learning walks related to scorpion home burrow navigation. J Exp Biol. 2022;225:jeb243947. [Open Access]

28 June, 2022

Updated information on the distribution of the genus Buthacus in Algeria.

 


Yacine Bengaid and co-workers recently published an article with new information about the distribution of the genus Buthacus Birula, 1908 (Buthidae) in Algeria.

Abstract:
The genus Buthacus Birula, 1908 (Family Buthidae) regroups about 30 species commonly known as sand scorpions. In the Algerian sandy deserts, in particular, this group shows a micro-endemic populations. The present paper summarizes the exhaustive list of Buthacus species in Ghardaïa region (Central Algeria), basing on sampling period of 12 months (2021). As a preliminary result, five species were recorded from the study area: B. arenicola, B. birulai, B. elmenia, B. samiae, and B. spinatus. Of which, two species are original from Algerian Eastern Erg (B. arenicola and B. birulai) while, the other species were recently identified from Ghardaïa region. All these species show a close affinity to Erg or sandy biotopes except B. samiae which presents a wide distribution in study area and in sandy Reg. Also, it has the ability to cohabit with other Buthacus such as B. spinatus in the North and B. elmenia in the south.

Reference:
Bengaid Y, Sadine SE, Oumyma Z, Abidi H, Bissati S, Houhamdi M. Notes and remarks on Buthacus species of Central Algeria (Scorpiones: Buthidae). Serket; 2022. p. 274-81.

Family Buthidae

A comparative study of two species of Odontobuthus from Iran

 


M. Fatemi and co-workers have recently published a study of two Odontobuthus Vachon, 1950 (Buthidae) from Iran, O. bidentatus Lourenço & Pezier, 2002 and O. doriae (Thorell, 1876). Odontobuthus is a medical significant genus in Iran and correct identification of the species in this genus is therefore important.

Abstract:
Scorpions are one of the most venomous animals which cause serious public health problems. The sting of scorpions can sometimes be fatal depending on the scorpion species involved. So far, sixty-six (66) scorpion species have been identified in Iran. Annually, about 40-50000 cases of scorpionism are reported in Iran. Odontobuthus doriae and O. bidentatus are among the most medically important scorpion species in Iran, and they are very similar to each other in coloration, carination, and trichobotrial patterns. This morphometric study aimed to compare some of the important morphological characteristics in order to identify the key differences between these two species. A total of 45 morphological characters were measured using calipers and stereomicroscope, and 55 morphological characters and ratios (relative of length to width ratio of morphological characters of scorpions) were analyzed. The independent sample t-test in SPSS software (version 24) was used for the statistical analyses in this study. The mean total length, carapace width, length of fixed and moveable fingers, and chelicerae length of O. doriae were greater than those of O. bidentatus in our study area. The morphological measurements displayed a clear distinction between O. doriae and O. bidentatus in our study area; therefore, they can be used as morphological identification keys for distinguishing between these two species.

Reference:
Fatemi M, Mohammadi Bavani M, Mohammadi A, Navidpour S, Rafinejad J. A Comparative Morphometric Study on Odontobuthus bidentatus and Odontobuthus doriae (Scorpionida: Buthidae) in Iran. Archives of Razi Institute. 2022;77(2):899-905. [Open Access]

Family Buthidae

27 June, 2022

An updated checklist of scorpions of China with several taxonomic comments

 


Victoria Tang just published an updated checklist of scorpions of China. China has a large diversity when it comes to scorpions and the present article lists 52 species belonging to 13 genera and six families. 

Tang's article also discuss many taxonomic issues with several of the taxa reported from China. No taxonomical decisions are made, but the author recommend further investigations into many of the uncertainties. I refer to the abstract and the article for details on these.

Abstract:
An updated checklist of scorpions of China (52 species belonging to 13 genera and six families) is provided, with Chinese name equivalents and an illustrated map of all localities. Colored photos of the Chinese population of Mesobuthus thersites (C. L. Koch, 1839) and one Olivierus sp. in vivo habitus are provided for the first time. The recent taxonomic changes are summarized. The monotypic genus Tibetiomachus (Hormuridae) with its single species T. himalayensis is considered a nomen dubium. The validity of the previously synonymized Scorpiops atomatus Qi et al., 2005 and S. validus (Di et al., 2010) (Scorpiopidae) is questioned, although they are not formally restored from synonymy. Olivierus hainanensis (Birula, 1904) (Buthidae) is possibly a junior synonym of O. martensii (Karsch, 1879); a reanalysis of the syntypes is warranted. The name “Scorpiops jingshanensis Li, 2016” is a nomen nudum. Additional comments are made upon two unavailable names that appear in an unpublished MS thesis (Zhang, 2009; in Chinese): “Mesobuthus beijiangensis” and “M. nanjiangensis”. A revision is needed of several species with weakly supported diagnostic characters, such as Olivierus bolensis (Sun et al., 2010) and Scorpiops puerensis (Di et al., 2010). The applicability of the diagnostic characters proposed for Olivierus bolensis (Sun et al., 2010) and O. longichelus (Sun & Zhu, 2010) is found to be unstable, based on the examination of some new specimens from Xinjiang. Their relationship with another two recently described species (O. mikhailovi Fet et al., 2021 and O. tarabaevi Fet et al., 2021), as well as the misidentified “Mesobuthus caucasicus intermedius” in China, remains unclear until a molecular study is accomplished.

Reference:
Tang V. Scorpions of China: an updated checklist with comments on some taxonomic issues (Arachnida: Scorpiones). Euscorpius. 2022(355):1-17. [Open Access]

23 June, 2022

New information about the costs of autotomy (tail loss) in scorpions

 


I have previously reported about the facinating discovery of autotomy of the cauda (tail) as an anti-predatory behavior in the scorpion Ananteris mauryi Lourenco, 1982 (Buthidae). The cauda contains important parts of the scorpion's nervous, circulatory and digestive systems, and of course the very important sting and the venom glands. The tail doesn't regenerate and an automized scorpion will eventually die from constipation (but can survive for several months befor it die).

I was recently made aware of three papers authored by Solimary García-Hernandez and Glauco Machado presenting research into the cost of autotomy (tail loss) in scorpions. One article stufy the effect of autotomy on predation success, the second article adresses short- and long-term consequences on locomotor performance of male and female sorpions with tail loss, and finally the third article studies the effects of autotomy on reproductive sucess.

To sum up, tail loss in scorpions has negative effects prey capture, exposure to predators, and reproductive success, but the size of the effects differ between the sexes. The reduction of reproductive succcess was much more dramatic for females than for males. For details on the results and conclusion I refer to the abstracts below.

Abstracts:

Paper1:
Predation success depends on factors such as hunger, prey size, prey availability and intensity of competition. A neglected factor that may also influence predation success is the proper function of morphological traits related to prey search, capture and manipulation. Injuries that compromise the functionality of these morphological traits may reduce predation success. In many invertebrates, autotomy can compromise predation success because the detached body part may be crucial for hunting. However, empirical evidence linking autotomy and predation success is relatively scarce. We filled this gap using the scorpion Ananteris balzani, which autotomizes the last abdominal segments, known as the ‘tail’. This is a unique form of autotomy as ‘tail’ autotomy implies the loss of the stinger, an organ used for venom inoculation, which is the main form of large prey subjugation. Using a paired experimental design, we found that for both small and large prey, subduing success was higher when individuals were intact than when they were autotomized. After autotomy, subduing success of male scorpions decreased
from 90% to 17% for small prey and from 47% to 1% for large prey. Subduing success of female scorpions after autotomy decreased from 98% to 93% for small prey and from 97% to 70% for large prey. Autotomized individuals took longer than intact individuals to subdue both small and large prey, but the effect size was higher for large prey. Considering that the tail does not regenerate, autotomized individuals (especially males) will experience a lifelong reduction in trophic niche breadth because their diet will be mostly composed of small prey. Moreover, autotomized individuals probably move more to enhance the likelihood of finding small prey, which may increase their exposure to predators and consequently the costs related to tail loss.

Paper 2:
In many taxa, individuals voluntarily detach a body part as a form to increase their chances of escaping predation. This defense mechanism, known as autotomy, has several consequences, such as changes in locomotor performance that may affect fitness. Scorpions of the genus Ananteris autotomize the “tail”, which in fact corresponds to the last abdominal segments. After autotomy, individuals lose nearly 25% of their body mass and the last portion of the digestive tract, including the anus, which prevents defecation and leads to constipation, because regeneration does not occur. Here, we experimentally investigated the short- and long-term effects of tail loss on the locomotor performance of Ananteris balzani. In a short-term experiment, the maximum running speed (MRS) of males and females did not change after autotomy. Moreover, the relative mass of the lost tail did not affect the change in MRS after autotomy. In a long-term experiment, autotomy had a negative effect on theMRS of males, but not of females. Autotomized over-fed individuals suffered from severe constipation but were not slower than autotomized normally fed individuals. In conclusion, tail loss has no immediate effect on the locomotor performance of scorpions. The long-term decrease in the locomotor performance of autotomized males may impair mate searching. However, because death by constipation takes several months, males have a long time to find mates and reproduce. Thus, the prolonged period between autotomy and death by constipation is crucial for understanding the evolution of one of the most extreme cases of autotomy in nature.

Paper 3:
The ability to detach a body part in response to a predation attempt is known as autotomy, and it is perhaps the most
intensively studied form of nonlethal injury in animals. Although autotomy enhances survival, it may impose reproductive costs on both males and females. We experimentally investigated how autotomy affects the reproductive success of males and females of a scorpion species. Individuals of Ananteris balzani autotomize the last abdominal segments (the tail), losing the anus and leading to lifelong constipation, since regeneration does not occur. Although the male tail is used during courtship and sperm transfer, autotomy has no effect on male mating success. The combined effect of increased mortality and reduced fecundity resulted in autotomized females producing nearly 35% fewer offspring than intact females. In conclusion, the negative effects of tail autotomy are clearly sex dependent, probably because the factors that influence reproductive success in males and females are markedly different.

References:

Paper1:
García-Hernández S, Machado G. ‘Tail’ autotomy and consequent stinger loss decrease predation success in scorpions. Anim Behav. 2020;169:157-67. [Subscription required for full text]

Paper 2:
Garcia-Hernandez S, Machado G. Short- and long-term effects of an extreme case of autotomy: does 'tail' loss and subsequent constipation decrease the locomotor performance of male and female scorpions? Integr Zool. 2021;Accepted Manuscript:1-17. [Subscription required for full text]

Paper 3:
García-Hernández S, Machado G. Fitness implications of nonlethal injuries in scorpions: Females, but not males, pay reproductive costs. Am Nat. 2021;197(3):379-89. [Open Access]

Thanks to Solimary García-Hernandez for sending me their articles on this interesting topic!

22 June, 2022

A revision of the Tityus forcipula species group and a new species from Colombia

 


Jairo Moreno-Gonzalez and co-workers have recently published an article with a revision of the Tityus forcipula species group, reducing the number of species beloning to this group. In addition, a new species of Tityus C. L. Koch, 1836 (Buthidae) is described from Colombia.

Tityus moralensis Moreno-Gonzalez, Pinto da Rocha & Cabra-Garcia, 2022

Abstract:
The Tityus forcipula species group has had an intricate taxonomic history, changing its diagnostic characters and composition on several occasions. One of the alleged reasons for this taxonomic uncertainty is the use of superficial characters (i.e. raw similarity instead of putative synapomorphies) for species group delimitation. Here, we conducted a thorough phenotypic survey across the Tityus forcipula species group, as currently delimited, including characters that had been suggested elsewhere as putative synapomorphies for delimiting lineages within Tityus. In doing so we also redescribe Tityus forcipula and describe a new species belonging to the Tityus forcipula species group: Tityus moralensis sp. nov. based on specimens from the Andean region of Valle del Cauca department, Colombia. The Tityus forcipula species group is here delimited to Andean species from Colombia and Ecuador that share strongly sclerotized and brown colored pectines, basal middle lamellae of female pectines dilated and suboval or ovoid shaped, basal plate of female pectines without glandular region and telotarsi with two ventrosubmedian rows (type II) of stout macrosetae (i.e., Tityus crassicauda, Tityus cuellari, Tityus forcipula, Tityus fuhrmanni and Tityus moralensis sp. nov). The new Tityus species is placed into a phylogenetic context with other buthid species using DNA sequences (COI and 28S). Finally, we provide a map with updated distributional records of the Tityus forcipula species group.

Reference:
Moreno-Gonzalez JA, Pinto da Rocha R, Cabra-Garcia J. On the Tityus forcipula species group: redescription of Tityus forcipula (Scorpiones, Buthidae), description of a new Andean species, and notes on the taxonomy of the group. Zootaxa. 2022;5155(2):151-86. [Subscription required for full text]

Thanks to Jairo and Ricardo for sending me their article!

Family Buthidae