Two cases of non-native scorpion introduction in Bermuda

 

The island of Bermuda has no native scorpions, but as for other countries lacking our favorite animal groups, they do get introduced stowaways. Danniella Sherwood and co-workers recently reported about two cases of introduced scorpions to the island, a Centruroides gracilis (Latreille, 1804) (Buthidae) and a unidentified species in the genus Hadruroides Pocock, 1893 (Caraboctonidae).

Even though we love scorpions, it is important that stowaways like this are intercepted to avoid more permanent populations to keep the endemic and native fauna safe.

Abstract:
Hadruroides sp. (Scorpiones: Caraboctonidae) is newly recorded as a successfully intercepted non-native invasive species in Bermuda, based on examination of a desiccated and damaged immature female specimen. A second record of an intercepted Centruroides gracilis (Latreille, 1804) (Scorpiones: Buthidae) is reported based on examination of an adult male.

Reference:
Sherwood D, Outerbridge M, Smith SR, Gosling J, Darrell M. Tails from the Isle of Devils: two new records of non-native invasive scorpions (Arachnida: Scorpiones) successfully intercepted in Bermuda, including the first record of Caraboctonidae. Euscorpius. 2026(435):1–3. [Open Access]

A new species of Hadruroides from Peru

 

Eric Ythier and Wilson Lourenco have recently described a new species of Hadruroides Pocock, 1893 (Caraboctonidae) from Southern Peru.

Hadruroides apu Ythier & Lourenco, 2023

The new species has been collected at an impressive elevation of 3,317 m.

Abstract:
A new species belonging to the genus Hadruroides Pocock, 1893 (family Caraboctonidae Kraepelin, 1905) is described on the basis of specimens collected in Apurimac region in Southern Peru. H. (Lourencoides) apu sp. n. appears to be related to H. (L.) mauryi Francke & Soleglad, 1980 and H. (L.) bustamantei Ochoa & Chaparro, 2008 but can be distinguished notably by a smaller size, different pigmentation pattern, reduced granulation, lower pectinal tooth count, metasoma with only the first segment wider than long and pedipalp chela slenderer in male and broader in female with fixed finger straight without proximal gap between fingers in both sexes. This new taxon represents the 18th known species of the genus Hadruroides reported from Peru and the 23rd species of the subgenus Lourencoides Rossi, 2014. The total number of Hadruroides species is now raised to 25.

Reference:
Ythier E, Lourenco WR. A new species of Hadruroides Pocock, 1893 from Peru (Scorpiones: Caraboctonidae). Faunitaxys. 2023;11(76):1-7. [Open Access]

Thanks to Eric for informing me about their new article!

Family Caraboctonidae

Two new species of Hadruroides from Peru and Ecuador

 

Eric Ythier recently publish an article describing two new species in the genus Hadruroides Pocock, 1893 (Caraboctonidae) from Peru and Ecuador.

Hadruroides inti Ythier, 2021

Hadruroides pachamama Ythier, 2021

Abstract:
Two new species belonging to the genus Hadruroides Pocock, 1893 (family Caraboctonidae Kraepelin, 1905) are described on the basis of specimens collected in Arequipa region in southern Peru, and Loja province in southern Ecuador. H. inti sp. n. represents the 17th known species of the genus Hadruroides reported from Peru, and the 22nd species of the subgenus Lourencoides Rossi, 2014. H. pachamama sp. n. represents the 7th known species of the genus Hadruroides reported from Ecuador, and the second species of the subgenus Hadruroides Rossi, 2014. The total number of Hadruroides species is now raised to 24.

Reference:
Ythier E. Two new species of Hadruroides Pocock, 1893 from Peru and Ecuador (Scorpiones, Caraboctonidae). Faunitaxys. 2021;9(11):1-8. [Open Access]

Thanks to Eric for sending me his article!

Family Caraboctonidae

Phylogenetic study gives Hadruridae family status ("Another one bites the dust")

There have been buzz about Carlos E. Santibáñez-López' and co-worker's new phylogenetic study of the family Caraboctonidae Kraepelin, 1905 for several months, but due to several reasons I have been slow to post this on the blog. But here it is and The Scorpion Files' family pages have also been updated.

I'm not going to go into details about the study here as I must admit that the more technical stuff is above my head, but I will list the main conclusions from the study:

1.
Hadrurinae Stahnke, 1973 is split from Caraboctonidae and elevated to family status, Hadruridae. Hadruridae consists of nine species in the two genera Hadrurus Thorell, 1876 and Hoffmannihadrurus Fet & Soleglad, 2004. Distributed in North America.

2.
Caraboctonidae now consists of 23 species in two two genera Caraboctonus Pocock, 1893 and Hadruroides Pocock, 1893. Distributed in South America.

3.
Two new superfamilies have been created: Caraboctonoidea Kraepelin, 1905 (Caraboctonidae and Superstitioniidae) and Hadruroidea Stahnke, 1974 (Hadruridae).

4.
The genera Uroctonus Thorell, 1876  (currently in Chactidae)  and Belisarius Simon, 1879 (currently in Belisaridae) are regarded as insertae sedis with respect to superfamilial placement.

More phylogenomic analyses will probably give us more insight in the complicated higher-level relationships in scorpions.

Abstract:
Historically, morphological characters have been used to support the monophyly, composition, and phylogenetic relationships of scorpion families. Although recent phylogenomic analyses have recovered most of these traditional higher level relationships as non-monophyletic, certain key taxa have yet to be sampled using a phylogenomic approach. Salient among these is the monotypic genus Caraboctonus Pocock, 1893, the type species of the family Caraboctonidae Kraepelin, 1905. Here, we examined the putative monophyly and phylogenetic placement of this family, sampling the library of C. keyserlingi Pocock, 1893 using high throughput transcriptomic sequencing. Our phylogenomic analyses recovered Caraboctonidae as polyphyletic due to the distant placement of the genera Caraboctonus and Hadrurus Thorell, 1876. Caraboctonus was stably recovered as the sister-group of the monotypic family Superstitioniidae Stahnke, 1940, whereas Hadrurus formed an unstable relationship with Uroctonus Thorell, 1876 and Belisarius Simon, 1879. Fourcluster likelihood mapping revealed that the instability inherent to the placement of Hadrurus, Uroctonus and Belisarius was attributable to significant gene tree conflict in the internodes corresponding to their divergences. To redress the polyphyly of Caraboctonidae, the following systematic actions have been taken: (1) the family Caraboctonidae has been delimited to consist of 23 species in the genera Caraboctonus and Hadruroides Pocock, 1893; (2) Caraboctonidae, previously included in the superfamily Iuroidea Thorell, 1876 or as incertae sedis, is transferred to the superfamily Caraboctonoidea (new rank); (3) the superfamily Hadruroidea (new rank) is established and the status of Hadrurinae Stahnke, 1973 is elevated to family (Hadruridae new status) including 9 species in the genera Hadrurus and Hoffmannihadrurus Fet & Soleglad, 2004 and (4) we treat Uroctonus and Belisarius as insertae sedis with respect to superfamilial placement. Our systematic actions engender the monophyly of both Iuroidea and Caraboctonidae. Future phylogenomic investigations should target similar taxon-poor and understudied

References:
Santibáñez-López CE, Ojanguren-Affilastro AA, Sharma PP. Another one bites the dust: Taxonomic sampling of a key genus in phylogenomic datasets reveals more non-monophyletic groups in traditional scorpion classification. Invertebrate Systematics. 2020;34(2):133-43. [Subscription required for full text]

Thanks to Carlos E. Santibáñez-López and Prashant P. Sharma who have kept me informed about their study. I have also been informed about this article by Kari McWest and Matt Simon. Big thanks to them!

Family Caraboctonidae
Family Hadruridae

Scorpions can actually smell their enemies

It has been known for a long time that scorpions can smell (detect chemical substances) with their pectines and pedipalpal fingers. Zia Nisani and Raul Curiel report for the first time that scorpions are also able to smell the presence of potential predators. In a research trial they were able to show that individuals of Hadrurus arizonensis (Ewing, 1928) (Caraboctonidae) changed behavior in the presence of odor from a potential predator. The advantages of such an ability is of course quite obvious.

Abstract:
Sensory ecology studies show that reception and utilization of information from the environment is a crucial life process. Scorpions possess a weapon that can be used against predators, but it remains unknown whether scorpions’ decision to use it is influenced by chemical cues from predators. We investigated the influence of predators’ odors on stinging behavior of Hadrurus arizonensis (Ewing, 1928) by stimulating them to sting under two conditions: in the presence of an odor from a potential rodent predator (Rattus norvegicus) and in the absence of such an odor. It took fewer probes to elicit a response when predator scent was present, and it resulted in more wet stings than the non-scented treatments. Finally, the smaller scorpions were more reactive than the larger ones. The variances in stinging behavior suggest that the detection of predator odors by H. arizonensis elevates its response in potentially threatening circumstances.

Reference:
Nisani Z, Curiel R. Antipredator responses of Hadrurus arizonensis (Scorpiones: Caraboctonidae) to chemosensory cue from a mammalian predator. J Arachnol. 2019;47:389-91. [Open Access]

The defense respons of scorpions to repeated attacks from a predator

Scorpions and other prey species are involved in a continuing arm race against their predators. The prey will get better in avoidance and defence and the predator tries to get better in overcoming the prey.

Mykola Rasko and co-workers have recently published a study investigating the sting use and venom expenditure during repeated attacks (simulated) in Hadurus arizonensis Ewin, 1928 (Caraboctonidae). Contrary to the projects expectations, the stinging behaviour, venom use and venom volume all decreased as the number of challenges increased. The scorpions defenses actually decreased during repeated attacks. This means that a predator of scorpions should use repeated attacks to overcome a scorpion, and this is also something that has been observed in some predators of scorpions.

Abstract:
Predatore-prey arms races ensure that a prey's defences are well matched with the predator's ability to overcome them. Scorpions have a formidable defensive capacity due to their venomous stinger. Mammalian and squamate scorpion predators overpower scorpions by making repeated attacks. We tested here how scorpions, Hadrurus arizonensis, apply their venom defensively during a simulated repeated attack, consisting of 10 consecutive challenges. Since the persistent repeated attack of a predator, even when stung in the process, seems to indicate its resolve, we expected defensive effort to increase with the number of challenges. We also expected that, owing to the life-and-death nature of a predatory attack, scorpions would be liberal in the use of their venom. We found, however, that stinging behaviour, venom use and venom volume all decreased as the number of challenges increased. Scorpions used only 7.8±9.6% (mean±SD) of their total venom volume during an attack consisting of 10 consecutive challenges. We conclude that a repeated attack seems an effective strategy for scorpion predators to reduce the defensive investment of scorpions.

Reference:
Rasko M, Coelho P, Simone Y, van der Meijden A. How to attack a scorpion: venom metering during a repeated attack. Anim Behav. 2018;145:125-9. [Subscription required for full text]

A desert scorpion can smell its enemies

Avoid being eaten or killed is one of the fundamental drives in all animals and an impressive range of anti-predator tactics have been described. Scorpions have their powerful claws and a venomous sting, but other tools are also available.

Zia Nisani and co-workers have now published a very interesting article showing that the desert scorpion Paruroctonus marksi (Haradon, 1984) (Vaejovidae) can actually smell the proximity of a potential predator (in this case the much larger scorpion Hadrurus arizonensis (Ewing, 1928) (Caraboctonidae)) and then avoid approaching it. This is the first evidence of airborne chemoreception as an anti-predator strategy in scorpions.

One of the experiments in this study point to a special constellation array of sensilla (or a yet unidentified structure) on the pedipalps as the "sense organ" used to detect the odors of predators.

Abstract:
Chemically induced predator avoidance behaviors exist in many arthropods. In this paper, we examined the behavioral responses of the desert scorpion, Paruroctonus marksi (Haradon, 1984), to airborne chemical cues from a natural predator, the larger scorpion Hadrurus arizonensis (Ewing, 1928). We used a Y-shaped, dual-choice olfactometer to test for avoidance behavior in the presence of a known predator, H. arizonensis. Prior to this study there has been little research done on chemically induced predator avoidance behaviors in scorpions. The results of this study suggest that P. marksi is capable of detecting a predator’s airborne cues, though the nature and identity of these cues remain unknown, and it appears that the constellation array of the fixed finger does function in detecting these cues. We also discuss the importance of adaptive predator avoidance behaviors.

Reference:
Nisani Z, Honaker A, Jenne V, Loya F, Moon H. Evidence of airborne chemoreception in the scorpion Paruroctonus marksi (Scorpiones: Vaejovidae). Journal of Arachnology. 2018;46:40-4. [Open Access]

Thanks to Matt Simon for informing me about this article!

An updated checklist of the scorpion fauna of Ecuador and a review on their medical importance

Gabriel Brito and Adolfo Borges have recently published an interesting article on the scorpion fauna of Ecuador. Ecuador is a hotspot for scorpion biodiversity and the authors present an updated checklist of the scorpion fauna of this country. Details of distribution and habitat are also presented.

The article also discuss the medical importance of the scorpion fauna of Ecuador.

Abstract:
Ecuador harbors one of the most diverse Neotropical scorpion faunas, hereby updated to 47 species contained within eight genera and five families, which inhabits the “Costa” (n = 17), “Sierra” (n = 34), “Oriente” (n = 16) and “Insular” (n = 2) biogeographical regions, corresponding to the western coastal, Andean, Amazonian, and the Galápagos archipelago regions, respectively. The genus Tityus Koch, in the family Buthidae, responsible for severe/fatal accidents elsewhere in northern South America and the Amazonia, is represented in Ecuador by 16 species, including T. asthenes, which has caused fatalities in Colombia and Panama, and now in the Ecuadorian provinces of Morona Santiago and Sucumbíos. Underestimation of the medical significance of scorpion envenoming in Ecuador arises from the fact that Centruroides margaritatus (Gervais) (family Buthidae) and Teuthraustes atramentarius Simon (family Chactidae), whose venoms show low toxicity towards vertebrates, frequently envenom humans in the highly populated Guayas and Pichincha provinces. This work also updates the local scorpion faunal endemicity (74.5 %) and its geographical distribution, and reviews available medical/biochemical information on each species in the light of the increasing problem of scorpionism in the country. A proposal is hereby put forward to classify the Ecuadorian scorpions based on their potential medical importance.

Reference:
Brito G, Borges A. A checklist of the scorpions of Ecuador (Arachnida: Scorpiones), with notes on the distribution and medical significance of some species. J Venom Anim Toxins Incl Trop Dis. 2015;21:23. [Open Access]

Thanks to Dr. Borges for sending me this article!

Scorpions of the Galapagos Islands

The Galapagos Islands are famous for their animals and their impact on our knowledge on animal evolution. But there are also scorpions present on most of the islands in the Galapagos archipelago. Baert & Mahnert have recently published a paper on the scorpion (and other non-spider) fauna of the islands.

Two species are present: Centruroides exsul (Meise, 1934) (Buthidae) and Hadruroides galapagoensis Maury 1975 (Carabotonidae).

Abstract:
The geographic and ecological distribution of the arachnid species belonging to the Amblypygi (Charinus insularis Banks, 1902), the Opiliones (Galanomma microphthalma Juberthie, 1970), the Schizomida (Schizomus portoricensis (Chamberlin, 1922)), the Scorpiones (Centruroides exsul (Meise, 1934) and Hadruroides galapagoensis Maury, 1975), the Solifugae (Neocleobis solitarius (Banks, 1902)) and 25 species of Pseudoscorpiones from the Galàpagos are described. Only the schizomid Schizomus portoricensis and the pseudoscorpions Paratemnoides nidificator (Balzan, 1888), Lechytia chthoniiformis (Balzan, 1887), Aphelolpium cayanum Muchmore, 1979, and Aphelolpium longidigitatum (Ellingsen, 1910) occur also on the American mainland. The pseudoscorpion Withius piger (Simon,1878) is a cosmopolite species.

Reference:
Baert L, Mahnert V. The distribution of the non‐araneae and non‐acari arachnids of Galápagos. Belgian Journal of Entomology. 2015;28:1-76. [Open Access]

Thanks to Rolando Teruel for sending me this article!

Three new species and a revision of the Ecuadorian species of Hadruroides

Andrea Rossi has recently published a revision of the mainland species of Hadruroides Pocock, 1893 (Caraboctonidae) in Ecuador. Three new species have been described:

Hadruroides doriai Rossi, 2014
Hadruroides elenae Rossi, 2014
Hadruroides moreti Rossi, 2014

An identification key for mainland species in the genus in Ecuador is presented.

Abstract:
The species of the genus Hadruroides Pocock, 1893 in Ecuador mainland are revised. Three new species related to H. maculatus (Thorell, 1876) are described: H. dorai, H. elenae and H. moreti. The genus Hadruroides is split into two subgenera: the nominal subgenus includes now only one species, H. charcasus (Karsch, 1879), whereas Lourencoides n. subgen. includes all other known species. A new record of H. charcasus in Ecuador is reported. The total number of Hadruroides species in Ecuador mainland is now raised to six and an identification key is given.

Reference:
Rossi A. A revision of the genus Hadruroides Pocock, 1893 in Ecuador mainland with the description of three new species, the definition of a new subgenus and a new record. Estratto Dagli Annali del Museo Civico di Storia Naturale "G Doria". 2014;106:193-210.

Thanks to Andrea Rossi for sending me this article!

Family Caraboctonidae

Three new Hadruroides species from Central Peru

Andrea Rossi has published three new species in the genus Hadruroides Pocock, 1893 (Caraboctonidae) from Central Peru.

Hadruroides adrianae Rossi, 2012
Hadruroides lourencoi Rossi, 2012
Hadruroides tongiorgii Rossi, 2012

The paper also has an identification key for Hadruroides in Peru.

Abstract:
Three new species of the neotropical genus Hadruroides POCOCK, 1893 are described from different habitats in central Peru. H. adrianae n. sp. comes from a xeric area around San Josè de Los Molinos, Ica province, in the Ica region. This is also the first record of this genus for that region. H. lourencoi n. sp. and H. tongiorgii n. sp. come from the Junín region, respectively from Tarma province, at very high altitude, and from the Andinian forest of Satipo province, at medium altitude. Only few specimens of Hadruroides are known from Junín and their identity was not clear. The total number of Peruvian species of Hadruroides is now raised to sixteen.

Reference:
Rossi A. Three new species of the genus Hadruroides pocock, 1893 from central Peru (Scorpiones: Caraboctonidae). Onychium. 2012;9 (2011-2012):10-26.

Thanks to Dr. Rossi for sending me his paper!

Family Caraboctonidae

Phylogeography of the Arizona Hairy Scorpion (Hadrurus arizonensis)

Matthew Graham and co-workers have recently published an interesting and extensive article on the phylogeography of the Arizona Hairy Scorpion (Hadrurus arizonensis Ewing, 1928 - family Caraboctonidae). Phylogeography is the study of the historical processes that may be responsible for the contemporary geographic distributions of individuals (Wikipedia).

The authors conclude that mitochondrial sequence data suggest that the phylogeography of H. arizonensis was shaped by a history of fragmentation, reduced gene flow and demographic expansion since the late Pliocene. See abstract below for more details.

Abstract:
Aim As data accumulate, a multi-taxon biogeographical synthesis of the Mojave Desert is beginning to emerge. The initial synthesis, which we call the ‘Mojave Assembly Model’, was predominantly based on comparisons of phylogeographical patterns from vertebrate taxa. We tested the predictions of this model by examining the phylogeographical history of Hadrurus arizonensis, a large scorpion from the Mojave and Sonoran deserts.
Location Mojave and Sonoran deserts, United States and Mexico.
Methods We sequenced mitochondrial cytochrome c oxidase subunit I (COI) data from 256 samples collected throughout the range of H. arizonensis. We analysed sequence data using a network analysis, spatial analysis of molecular variance (SAMOVA), and a Mantel test. We then used a molecular clock to place the genetic patterns in a temporal framework. We tested for signals of expansion using neutrality tests, mismatch distributions and Bayesian skyline plots. We used Maxent to develop current and late-glacial species distribution models from occurrence records and bioclimatic variables.
Results Phylogenetic and structure analyses split the maternal genealogy basally into a southern clade along the coast of Sonora and a northern clade that includes six lineages distributed in the Mojave Desert and northern Sonoran Desert. Molecular dating suggested that the main clades diverged between the late Pliocene and early Pleistocene, whereas subsequent divergences between lineages occurred in the middle and late Pleistocene. Species distribution models predicted that the distribution of suitable climate was reduced and fragmented during the Last Glacial Maximum.
Main conclusions Genetic analyses and species distribution modelling suggest that the genetic diversity within H. arizonensis was predominantly structured by Pleistocene climate cycles. These results are generally consistent with the predictions of Pleistocene refugia for arid-adapted taxa described in the Mojave Assembly Model, but suggest that a northern area of the Lower Colorado River Valley may have acted as an additional refugium during Pleistocene glacial cycles.

Reference:
Graham MR, Jaeger JR, Prendini L, Riddle BR. Phylogeography of the Arizona hairy scorpion (Hadrurus arizonensis) supports a model of biotic assembly in the Mojave Desert and adds a new Pleistocene refugium. Journal of Biogeography. 2013. Epub 30 Jan 2013. [Full text required for full text]

Thanks to Matthew Graham for sending me his paper!

Density, spatial distribution and biomass of Hoffmannihadrurus gertschi

Ana Quijano-Ravell and co-workers have recently published an article on the density, spatial distribution and biomass of Hoffmannihadrurus gertschi (Soleglad, 1976) (Caraboctonidae)* in an area in Mexico.

The paper is written in Spanish so I have only read the English abstract.

[*The authors have placed this species in Hadrurus, but it was transfered to Hoffmannihadrurus by Fet & Soleglad i 2008 and this species is listed as Hoffmannihadrurus gertschi (Soleglad, 1976) in The Scorpion Files. Some scientists disagree on the validity of Hoffmannihadurus, as this paper is an example of. Also, some scientists choose to put Hadrurus in Iuridae and reject the validity of Caraboctonidae. See details here.]

Abstract:
Density, spatial dispersion and biomass of Hadrurus gertschi Soleglad 1976 were estimated from field data obtained during a year of observations at “La Coronilla” hill in the municipality of Tepecoacuilco de Trujano, Guerrero, Mexico. Five quadrants of 400 m2 with differing slope exposures were used. The highest density was recorded in the quadrant without slope or “flat quadrant” with 0.3450 burrows per m2 and the southern exposure quadrant (0.2300 burrows per m2). The lowest densities occurred in the quadrants with northern and western exposures (0.1325 and 0.0825 burrows per m2 respectively). The highest values of the year were recorded in the months of May to July. The spatial dispersion of burrows in all exposures studied corresponds with a clumped distribution according to the Morisita Index. Average dry weight of adults was 2.22 ± 0.73 g and 6.4 ± 0.89 g in fresh weight. The juveniles weighted 0.08 ± 0.05 g in dry weight and 0.2 of fresh weight instar II and 1.10 ± 0.41 g dry weight and 3.63 ±1.95 g in fresh weight in the preadult stage. The biomass per ha was estimated in 2471.26 g of dry weight and 6190.02 g of fresh weight.

Reference:
Quijano-Ravell AF, Ponce-Saavedra J, Francke OF. Densidad, distribucion espacial y biomasa de Hadrurus gertschi Soleglad (Scorpiones, Iuridae) en una localidad de Guerro, Mexico. Revista Iberica de Arachnologia. 2012;20:35-43.

Thanks to Dr. Francke for sending me this paper!

Family Caraboctonidae

Burrows and burrowing in Hadrurus arizonensis

Daniel Hembree and co-workers have recently published a paper describing the forms and shapes of Hadrurus arizonensis Ewing, 1928 (Caraboctonidae) burrows. The authors are geologists (and/or palaentologists), and the angle and terminology of this papers is somewhat different from what I'm used to from the traditional scorpion literature. I must admit there are quite a few terms in the paper that unknown to me (but praise Google for being a helpful friend ;)

The goal of the paper is both to learn more about scorpion burrows, but also to aid in the recognition of scorpion burrows in the fossil record and to determine if aspects of palaeoenvironment can be ascertained by variations in scorpion burrow morphology.

The paper also has a nice mini-review of scorpion burrowing behavior and several pictures of burrow castings showing the form and shape of Hadrurus burrows.

Abstract:
Bioturbation by terrestrial animals is common in arid and semi-arid continental environments. Scorpions have comprised a significant portion of the diversity of predatory arthropods in these environments from the Late Paleozoic to the Recent. Many scorpions are active burrowers and likely have a substantial, if rarely recognized, ichnofossil record. This project involved the study of the burrowing behaviors and trace morphologies of the scorpion Hadrurus arizonensis (Scorpiones: Caraboctonidae). Individual animals were placed into sediment-filled terrariums for two- to three-week periods after which burrows were cast, excavated, and described. Descriptions of the subsurface structures included architecture, dimensions, bioglyphs, complexity, and tortuosity. Additional experiments were run with differing sediment composition, density, and moisture to evaluate the animal’s behavioral response to altering environmental conditions. Specimens of H. arizonensis burrowed by scratching and kicking loose sediment from the subsurface with the first two to three pairs of walking legs. The subsurface biogenic structures produced consisted of subvertical ramps, U-shaped burrows, helical burrows, and mazeworks. In the process of excavating the burrows, the desert scorpions also produced a hummocky surface topography as well as structures in dry, sandy sediment that resembled lamination and ripple cross-lamination. Increasing clay content and sediment density increased the complexity of burrow architectures produced. Reducing these variables limited the complexity of the burrows, reduced their likelihood of preservation, and increased the abundance of biogenic cross-lamination. Data collected from these and similar experimental studies can be applied to terrestrial ichnofossil assemblages in order to better interpret the paleoecology of ancient soil ecosystems.

Reference:
Hembree DI, Johnson LM, Tenwalde RW. Neoichnology of the desert scorpion Hadrurus arizonensis: burrows to biogenic cross lamination. Palaeontologia Electronica. 2012;15(1):1-34. [ Free full text]

Thanks to Jahn Hornung for informing me about this paper!

Life cycle of Hadrurus gertschi from Mexico

Ana Quijano-Ravell and co-workers have now published a study on the life cycle of Hadrurus gertschi Soleglad, 1976 (Caraboctonidae)*

[*This species was transfered to Hoffmannihadrurus by Fet & Soleglad i 2008 and this species is listed as Hoffmannihadrurus gertschi (Soleglad, 1976) in The Scorpion Files. Some scientists disagree on the validity of Hoffmannihadurus, as this paper is an example of. Also, some scientists choose to put Hadrurus in Iuridae and reject the validity of Caraboctonidae. See details here.]

Abstract:
The life cycle of Hadrurus gertschi Soleglad 1976 was reconstructed from field data taken during one year of observations in “La Coronilla”, near Ahuehuepan, in Tepecoacuilco de Trujano municipality, Guerrero, Mexico. The species inhabits tropical dry schrub forest in sympatry with three other scorpion species: Centruroides limpidus (Karsch 1879), Vaejovis variegatus Pocock 1898 and Vaejovis atenango Francke and González-Santillán 2007. A growth factor of 1.27 for the carapace length was determined and then used to estimate the morphometric changes between each instar to reach the adult stage and compared them with data obtained in the field. We concluded that this species requires 7 instars and 6 molts, and at least four years to reach adulthood. We also present the phenology of Hadrurus gertschi during one year, measured in relative abundance and surface activity pattern. Matting activity was observed in July, August, September and October.

Reference:
Quijano-Ravell AF, Ponce-Saavedra J, Francke OF. Ciclo de vida de Hadrurus gertschi Soleglad (Scorpiones, Iuridae) en una localidad del Estado de Guerrero, Mexico. Revista Iberica de Arachnologia. 2011;19(133-145).

Thanks to Oscar Francke for sending me this paper!

Family Caraboctonidae

A discussion on Hadrurus and a new species

Michael Soleglad and co-workers have recently published a paper discussing the taxonomy and phylogeny of the Hadrurus "spadix" subgroup (Caraboctonidae). A new species from parts of USA and Mexico is also described:

Hadrurus anzaborrego Soleglad, Fet & Lowe, 2011

Data suggest that Hadrurus obscurus is only a color variant of H. spadix, but more investigations are necessary before a formal deccission can be made.

The paper has an identification key for both Hadrurus and Hoffmannihadurus.

Abstract:
In this study new data are presented on the “spadix” subgroup of genus Hadrurus, including the description of a new species, H. anzaborrego, sp. nov., found primarily in the Anza-Borrego Desert State Park (ABDSP) in southern California, USA. This species is distinguished by its internal trichobothrial pattern of the chela and its unique carapace pattern. The status of Hadrurus obscurus Williams, 1970 is discussed and new locality data for this species are provided. A phylogenetic key to the genera, species, and subspecies of subfamily Hadrurinae is provided.

Reference:
Soleglad ME, Fet V, Lowe G. Contributions to scorpion systematics. IV. Observations on the Hadrurus "spadix" subgroup with a description of a new species (Scorpiones: Caraboctonidae). Euscorpius. 2011(112):1-36. [Free fulltext, but large file (17 mb). The paper divided into smaller files is available on the publishers website)]

Family Caraboctonidae

More on the genera Hadrurus and Hoffmannihadrurus

Michael Soleglad and Victor Fet have recently published a paper with further observations on the genera Hadrurus Thorell, 1876 and Hoffmannihadrurus Fet & Soleglad, 2004 (both Caraboctonidae).

Abstract:
Multiple populations of Hadrurus pinteri from Baja California Sur, Mexico have been examined. It is demonstrated that the southern populations of this species have a larger number of accessory trichobothria (neobothriotaxy) than the northern populations, numbers exceeding the maximum currently recorded for the genus. Examination of carapace and chela coloration and its patterns show a close affinity between H. pinteri and the dark phase of H. concolorous. A new morphometric ratio of the carapace is defined that distinguishes Hadrurus from Hoffmannihadrurus, further supporting the monophyly of the latter genus.

Reference:
Soleglad ME, Fet V. Further observations on scorpion genera Hadrurus and Hoffmannihadrurus (Scorpiones, Caraboctonidae). ZooKeys. 2010;59:1-13. [Free fultext]

Thanks to Victor Fet for sending me this paper!

Family Caraboctonidae

Six new Hadruroides from Peru

Jose Ochoa and Lorenzo Prendini have recently published six new species in the genus Hadruroides (Caraboctonidae*) from Peru:

Hadruroides chinchaysuyu Ochoa & Prendini, 2010*
H. geckoi Ochoa & Prendini, 2010*
H. graceae Ochoa & Prendini, 2010*
H. juanchararroi Ochoa & Prendini, 2010*
H. tishqu Ochoa & Prendini, 2010*
H. vichayitos Ochoa & Prendini, 2010*

*The authors prefer to use the Prendni & Wheeler system for higher scorpion taxonomy and have listed Hadruroides as a member of the family Iuridae.

The authors have included an indentification key for Hadruroides in Peru.

Abstract:
We review the taxonomy of the Hadruroides Pocock, 1893 (Iuridae: Caraboctoninae), scorpions of Peru, describe six new species from the north of the country, and report new records of other poorly known species. The description of these species raises to 16 the number of described species in the genus, 13 of which occur in Peru. Four species inhabit dry forest in northern Peru: H. charcasus (Karsch, 1879); H. chinchaysuyu, n. sp.; H. geckoi, n. sp.; H. leopardus Pocock, 1900. Three species occur in inter-Andean valleys along the Cordillera: H. bustamantei Ochoa and Chaparro, 2008; H. carinatus Pocock, 1900; H. mauryi Francke and Soleglad, 1980. Six species inhabit desert along the Pacific coast: H. aguilari Francke and Soleglad, 1980; H. graceae, n. sp.; H. juanchaparroi, n. sp.; H. lunatus (L. Koch, 1867); H. tishqu, n. sp.; H. vichayitos, n. sp. Most species of Hadruroides have restricted distributions, except H. charcasus and H. lunatus, which are apparently more widely distributed. We consider it necessary to reassess all previous records of the latter two species, because we suspect several are based on misidentifications.

Reference:
Ochoa JA, Prendini L. The Genus Hadruroides Pocock, 1893 (Scorpiones: Iuridae), in Peru: New Records and Descriptions of Six New Species. American Museum Novitates. 2010 Jun(3687):1-56. [Free fulltext]

Family Caraboctonidae

Sting use in prey capture

One of the conclusions from my master thesis many years ago was that sting use is probably costly for scorpions and because of this they will only use their stinger if the prey is large and/or the prey resists capture.

Now, Martin Edmunds and Richard Sibly have published a similar study with similar conclusions, using Hadrurus spadix Stahnke, 1940 (Caraboctonicae).

Abstract:
Since venom is costly to produce and stinging is not obligatory in prey capture for scorpions, the need to optimize use of resources suggests that venom should be reserved for prey that cannot otherwise be overpowered, (i.e., larger and/or more active prey). In accordance with these predictions, sting use by Hadrurus spadix Stahnke 1940 increased with prey size, reaching 100% once prey items were longer than the scorpion’s pedipalp patella length, and with prey activity, which we manipulated by varying prey temperature. Surprisingly, the scorpions were slower to capture less active (cooler) prey than those that exhibited higher rates of activity. We suggest this is because prey are located by vibrations in the substrate, with less active prey producing fewer vibrations.

Reference:
Edmunds MC, Sibly RM. Optimal sting use in the feeding behavior of the scorpion Hadrurus spadix. Journal of Arachnology. 2010;38(1):123-5. [Subscription required for fulltext, but free fulltext after 12 months].

A new Hadruroides from Peru

Ochoa & Chaparro described a new species of Hadruroides (Caraboctonidae) in 2008 (but I didn't learn about this paper until now):

Hadruroidews bustamantei Ochoa & Chaparro, 2008

Abstract:
Hadruroides bustamantei, a new caraboctonid species from inter Andean valleys of central Peru (2600—3289 m) is described. This species is most related to H. mauryi Francke & Soleglad, with which was confused. The new species differs from H. mauryi, by length/width ratio of the male chela and the pigmentation pattern of the tergites, legs and metasomal segments. With

Reference:
Ochoa JA, Chaparro JC. A new scorpion species of the genus Hadruroides (Scorpiones: Caraboctoninae) from inter Andean valleys of Peru. Rev Peru Biol. 2008;15(1):5-10. [Free fultext]

Thanks to Gerard Dupre for always helping me to keep The Scorpion Files updated!!

Family Caraboctonidae