24 August, 2017

Differences in mating behavior between two geographically separated populations of Bothriurus bonariensis

Paola Olivero and co-workers have recently published a study of the mating behavior of two allopatric populations of the Neptropical scorpion Bothriurus bonariensis (C.L. Koch, 1842) (Bothriuridae).

The authors found significant differences in mating patterns, including differences in the frequency and duration of important stimulatory courtship behaviors. Another interesting finding was that most inter-population matings were unsuccessful.

Courtship and mating behavior generally evolve rapidly in diverging populations and species. The adaptation to different environments may cause behavioral divergence in characteristics involved in matechoice. Our objective in this study was to compare the sexual behavior of two distant populations of thescorpion Bothriurus bonariensis. This species has a broad distribution in South America, inhabiting Central Argentina, Uruguay and south-eastern Brazil. It is known that in this species there is a divergence in morphological patterns (body size, coloration, allometry and fluctuating asymmetry indexes) among distant populations. Considering the differences in environmental conditions between localities, we compare the sexual behavior in intra-population and inter-population matings from Central Argentina and southern Uruguay populations. We found significant differences in mating patterns, including differences in the frequency and duration of important stimulatory courtship behaviors. In addition, most inter-population matings were unsuccessful. In this framework, the differences in reproductive behavior could indicate reproductive isolation between these populations, which coincides with their already known morphological differences. This is the first study comparing the sexual behavior of allopatric populations of scorpions; it provides new data about the degree of intraspecific geographical divergence in the sexual behavior of B. bonariensis.

Olivero PA, Mattoni CI, Peretti AV. Differences in mating behavior between two allopatric populations of a Neotropical scorpion. Zoology (Jena). 2017; Article in Press. [Subscription required for full text]

18 August, 2017

The holotype of Pandinus imperator has been rediscovered

The Emperor Scorpion, Pandinus imperator (C. L. Koch, 1841) (Scorpionidae), is probably the most famous scorpion species due to its impressive size and its history in the pet industry. The holotype was considered lost for a long time, but has now been rediscovered and redescribed by Joachim Holstein and co-workers in a recent article.

The holotype of the Emperor Scorpion Pandinus imperator (C.L. Koch, 1841) was long believed to have been lost. In 2015, as scientists at the State Museum of Natural History in Stuttgart were digitizing its entomological collections, they rediscovered the specimen on which Koch had based his description of the scorpion in 1841.

Holstein J, Wendt I, Rossi A. The Emperor is back! Rediscovery and redescription of the holotype of Pandinus imperator (Scorpiones: Scorpionidae). Arachnologische Mitteilungen. 2017;54:44-7.

Thanks to Andrea Rossi and Ingo Wendt for both sending me this article!

Family Scorpionidae

15 August, 2017

A new species of Megacormus from Mexico

Edmundo Gonzalez-Santillan and co-workers have recently described a new species of Megacormus Karsch, 1881 (Euscorpiidae) from an oak-pine forest in Guanajuato, México.

Megacormus xichu Gonzalez-Santillan, Gonzalez-Ruiz & Escobedo-Morales, 2017

 The article has an updated indentification key for the genus.

The fifth species of the genus, Megacormus xichu sp. nov., is described and compared to the other species. An identification key to these species as well as a distributional map with localities taken from the literature are provided.

Gonzalez-Santillan E, Gonzalez-Ruiz JM, Escobedo-Morales LA. A new species of Megacormus (Scorpiones, Euscorpiidae) from an oak-pine forest in Guanajuato, México with an identification key to the species in the genus. Zootaxa. 2017;4299(2):221-37. [Subscription required for full text]

Thanks to Edmundo Gonzalez-Santillan for sending me their article!

09 August, 2017

Weapon of choice should reflect the level of threat

Several studies have directly or indirectly shown that at least some scorpion species abide by the venom optimization hypothesis both in sting and venom use. A scorpion's choice of weapon should reflect the level of threat (or the level of resistance of a prey).

Andre Lira and co-workers have recently published an article showing that Tityus stigimurus (Thorell, 1876) (Buthidae) reacts differently depending on the level of threat. Higher threat level caused a more aggressive behavior and more use of the main venom (instead of the metabolic more "cheaper" prevenom).

Venom demands high metabolic costs of the organisms that produce it because it is comprised of a complex mixture of various toxins. Due to this high cost, venomous animals modulate the amount or type of venom used depending on factors such as size of prey or intensity of predation threat. This paper shows that Tityus stigmurus, a prevalent scorpion species in the urban environment in the Northeast of Brazil, modulates its venom in response to different levels of stimuli. Sixty animals were collected in Vitória de Santo Antão, Pernambuco. The animals were subjected to either high or low levels of threats. During the tests, the animals were gently touched five times on the mesosoma with forceps at an interval of 5 s (high threat) or 5 min (low threat). The response varied significantly between intensity levels, with the animals exposed to low threat stinging in 70% of the observations and releasing a clear venom. In contrast, individuals subjected to a high level of threat stung in 83% of the observations and released a milky venom. Our results suggest that T. stigmurus reacts differently depending on the stimulus level. When the threat was considered high, the animal reacted more aggressively. Our results support the assumption that milky venom is only used when the animal is highly stressed because this venom represents higher metabolic costs than the production of clear venom.

Lira AF, Santos AB, Silva NA, Martins RD. Threat level influences the use of venom in a scorpion species, Tityus stigmurus (Scorpiones, Buthidae). Acta Ethologica. 2017;Published online 03.08.17:1-5. [Subscription required for full text]

Thanks to Andre Lira for sending me this article!

08 August, 2017

A new species of Hemiscorpius from Iran

Frantisek Kovarik and co-workers have recently published a new species in the medical significant genus Hemiscorpius Peters, 1861 (Hemiscorpiidae) from Iran.

Hemiscorpius shahii Kovarik, Navidour & Soleglad, 2017

Hemiscorpius shahii sp. n. from Iran, Hormozgan Province, is described and compared with other species of Hemiscorpius genus. The new species is characterized mainly by total length of 84 (female) to 110.7 (male) mm and unique trichobothrial pattern of pedipalp patella. The number of external trichobothria on patella is 17–18 (5 eb, 4 esb, 2–3 em, 3 est, 3 et); the number of ventral trichobothria on patella is 14–16. This distinguishes H. shahii sp. n. from all other species of genus Hemiscorpius, which have 3 or 10–12 ventral trichobothria on patella, one or two trichobothria in patella est series, and two or three trichobothria in esb series.

Kovarik F, Navidpour S, Soleglad ME. Hemiscorpius shahii sp. n. from Iran (Scorpiones: Hemiscorpiidae). Euscorpius. 2017(249):1-9. [Open Access]

Family Hemsicorpiidae

04 August, 2017

The acid in the venom makes a scorpion's sting extra painful

Fortunately, most scorpions are harmless to humans. But getting stung usually hurt, and for many buthids it hurts a lot. It is known that special toxins (peptids) in the venom cocktail are responsible for the pain, but a new study by Shilong Yang, and co-workers shows that the acid in the venom increase the pain effects of the toxins significantly and thereby maximizing the toxin potency.

If you want to learn more about this study, check out this blog report from Phys Org that explains the mechanism more in detail.

Venomous animals use peptide toxins for hunting and self-defense. To achieve these goals, toxins need to bind to their targets with high affinity due to the small amount that a single bite or sting can deliver. The scorpion toxin BmP01 is linked to sting-induced excruciating pain; however, the reported minimum concentrations for activating TRPV1 channel or inhibiting voltage-gated potassium (Kv) channels (both in the micromolar range) appear too high to be biologically relevant. We show that the effective concentration of BmP01 is highly pH-dependent—it increases by about 10-fold in inhibiting Kv channels upon a 1-U drop in pH but decreases more than 100-fold in activating TRPV1. Mechanistic investigation revealed that BmP01 binds to one of the two proton-binding sites on TRPV1 and, together with a proton, uses a one-two punch approach to strongly activate the nociceptive channel. Because most animal venoms are acidic, proton-facilitated synergistic actionmay represent a general strategy for maximizing toxin potency.

Yang S, Yang F, Zhang B, Lee BH, Li B, Luo L, et al. A bimodal activation mechanism underlies scorpion toxin–induced pain. Science Advances. 2017;3(8). [Open Access]

01 August, 2017

A new substitute name for Butheolus pallidus

Wilson Lourenco and Andrea Rossi have recently published an article with a new replacement name for Butheolus pallidus Lourenço & Duhem, 2012 (Buthidae). The reason for this is that it has been discovered that this name is preoccupied by Butheolus pallidus Pocock, 1897 (currently under the genus Orthochirus Karsch, 1891).

The new name for this species from Oman and United Arab Emirates is Butheolus hallani Lourenço & Rossi, 2017. [Author information corrected 17.08.17]

A nomen novum is proposed for Butheolus pallidus Lourenço et Duhem, 2012, a primary junior homonym of Butheolus pallidus Pocock, 1897 (currently Orthochirus pallidus).

Lourenco WR, Rossi A. A new substitute name for Butheolus pallidus Lourenço et Duhem, 2012 (Scorpiones, Buthidae), species described from United Arab Emirates/Oman. Arachnida - Rivista Aracnologica Italiana. 2017;3(13):42-4.

Thanks to Joel Hallan for sending me this article!

Family Buthidae