27 September, 2017

Increased predator exposure changes scorpion venom cocktail to become a more effective weapon

I just came across a very interesting article on phenotypic plasticity in scorpion venom. Scorpion venom is a cocktail of different toxins having different effects on different targets (e.g. one toxin is effective against invertebrates, another against mammals and a third against both). The matter in question in the current study is if scorpions are able to modify the ‘recipe’ of its venom cocktail, and thereby optimizing the fitness benefits of its costly venom, in different environments exhibiting differences in densities and types of predators and prey.

The Australian species Hormurus waigiensis (Gervais, 1843) (Hormuridae) was used in this study.

And interestingly, the results showed that simulated predator exposure appeared to decrease relative production of strong invertebrate toxins, while generally increasing the production of a section of the venom profile with activity towards mammalian cells. Put in other words, it seems that at least in Liocheles waigensis, increased interactions with a potential predator will cause the venom to become more effective (dangerous) against the predator and less effective against invertebrate prey.

So don't provoke your scorpions! This may make them more dangerous ;)

Animals embedded between trophic levels must simultaneously balance pressures to deter predators and acquire resources. Venomous animals may use venom toxins to mediate both pressures, and thus changes in this balance may alter the composition of venoms. Basic theory suggests that greater exposure to a predator should induce a larger proportion of defensive venom components relative to offensive venom components, while increases in arms races with prey will elicit the reverse. Alternatively, reducing the need for venom expenditure for food acquisition, for example because of an increase in scavenging, may reduce the production of offensive venom components. Here, we investigated changes in scorpion venom composition using a mesocosm experiment where we manipulated scorpions’ exposure to a surrogate vertebrate predator and live and dead prey. After six weeks, scorpions exposed to surrogate predators exhibited significantly different venom chemistry compared with naive scorpions. This change included a relative increase in some compounds toxic to vertebrate cells and a relative decrease in some compounds effective against their invertebrate prey. Our findings provide, to our knowledge, the first evidence for adaptive plasticity in venom composition. These changes in venom composition may increase the stability of food webs involving venomous animals.

Gangur AN, Smout M, Liddell MJ, Seymour JE, Wilson D, Northfield TD. Changes in predator exposure, but not in diet, induce phenotypic plasticity in scorpion venom. Proc Biol Sci. 2017;284(1863). [Subscription required for full text]

18 September, 2017

A new, extinct species of Centruroides found in amber from Mexico

Wilson Lourenco has recently described a new species of Centruroides Marx, 1890 (Buthidae) found in amber from Chiapas, Mexico.

Centruroides knodeli Lourenco, 2017

The new species is extinct. Please note that this species is not listed in The Scorpion Files as the species list only list extant species.

The article also includes criticisms of a recent article published by Rolando Teruel where two extinct species of Tityus C. L. Koch, 1836 (Buthidae) also found in amber were synonymized with Tityus geratus Santiago-Blay & Poinar, 1988. The following two species are restored as valid species.

Tityus azari Lourenço, 2013

Tityus (Brazilotityus) hartkorni Lourenço, 2009

Centruroides knodeli sp. n., a new species of fossil scorpion, is described from a specimen in amber from Chiapas, Mexico. The new species is clearly related to the extant fauna of the Neotropical region and is placed in the genus Centruroides Marx, 1890, presently distributed in North, Central and South America and in the Caribbean region. Also, the fossil species Tityus hartkorni Lourenço, 2009 and Tityus azari Lourenço, 2013, described from Dominican amber and inappropriately regarded by Rolando Teruel as junior synonyms of Tityus geratus Santiago-Blay & Poinar, 1988, are herein restored as valid taxa.

Lourenco WR. A new species of Centruroides Marx, 1890 from Chiapas amber, Mexico (Scorpiones: Buthidae). Revista Iberica de Arachnologia. 2017(30):100-6.

14 September, 2017

Two new species of Grosphus from Madagascar

Wilson Lourenco and co-workers have recently published an article describing two new species of Grosphus Simon, 1880 (Buthidae) from Madagascar.

Grosphus halleuxi Lourenço, Wilme, Soarimalala & Waeber, 2017

Grosphus rakotoariveloi Lourenço, Wilme, Soarimalala & Waeber, 2017

Grosphus simoni Lourenco, Goodman & Ramilijaona, 2004 is redescribed. The biogeography of the mentioned species is also discussed.

A reanalysis of the type material of Grosphus simoni Lourenço, Goodman & Ramilijaona, 2004, associated with new material of this species from the northeast of Madagascar, has led to the conclusion that the male paratype of G. simoni belongs to a new, undescribed species. A large series of specimens collected in the Ambatovy-Analamay-Torotorofotsy humid forests, at around 1000 m, revealed the presence of another new species, also associated to G. simoni. Thanks to the supplementary material, with males and females, a new diagnosis is proposed for G. simoni and two new species are here described. Some general comments on the biogeography of the two new species and G. simoni are also provided.

Lourenco WR, Wilme L, Soarimalala V, Waeber PO. Species of Grosphus Simon, 1880 associated to Grosphus simoni Lourenço, Goodman & Ramilijaona, 2004 with description of two new species (Scorpiones: Buthidae). Revista Iberica de Arachnologia. 2017(30):61-9.

Family Buthidae

12 September, 2017

A new species of Broteochactas from Brazil

Wilson Lourenco has recently described a new species of Brotheochactas Pocock, 1893 (Chactidae) from Brazilian Amazonia.

Broteochactas purus Lourenco, 2017

A new contribution to the knowledge of the scorpions belonging to the genus Broteochactas Pocock, 1893 is proposed and a new species is described, Broteochactas purus sp. n., based on one female specimen collected in the region of Beruri near the River Purus in the State of Amazonas, Brazil. The new species is characterized by a small size, an intense reddish to reddish yellow coloration, body and appendages with punctation and metasomal segment V and telson with conspicuous spinoid granulations.

Lourenco WR. One more new species of Broteochactas Pocock, 1893 (Scorpiones: Chactidae) from Brazilian Amazonia. Revista Iberica de Arachnologia. 2017(30):11-4.

Family Chactidae

08 September, 2017

A new species of Ananteris from Brazil

Andre Felipe de Araujo Lira and co-workers have recently described a new species of Ananteris Thorell, 1891 (Buthidae) from the Caatinga biome in Brazil.

Ananteris otovianoi Lira, Pordeus & Ribeiro de Albuquerque, 2017

We describe a new species of scorpion from the Caatinga of the state of Pernambuco, Brazil. Ananteris otovianoi sp. nov. can be distinguished from other Ananteris by the following combination of characters: blackish brown spots up to the medical surface of the chelicerae; pectinal tooth count and some structures measurements. In addition, data on natural history are showed and discussed. 

Lira AFA, Pordeus LM, Ribeiro de Albuquerque CM. A New species of Ananteris (Scorpiones: Buthidae) from Caatinga biome, Brazil. Acta Arachnologica. 2017;66(1):9-15. [Open Access, but pdf for this issue is not yet available]

Thanks to Andre Lira for sending me their article!

Family Buthidae

05 September, 2017

The Scorpion Fauna of Mona Island, Puerto Rico and a few taxonomical changes

Rolando Teruel and co-workers have been able to examine new materials from Mona Island, Puerto Rico and have published an article with updates on the scorpion fauna of this island. In addition, the following taxonomical decissions have been made:

Centruroides mariaorum Santiago-Blay, 2009 is synonymized with C. bani Armas & Marcano Fondeur, 1988.

The previous synonymization of Rhopalurus virkkii Santiago-Blay, 2009 with Heteroctenus abudi (Armas et Marcano Fondeur, 1987) is confirmed.

The scorpion fauna of the small Mona Island (= Isla de Mona), located roughly midway between Hispaniola and Puerto Rico and administratively belonging to the latter, is herein revised. Three species are confirmed to occur: the buthids Centruroides bani Armas et Marcano Fondeur, 1987 and Heteroctenus abudi (Armas et Marcano Fondeur, 1987), plus the diplocentrine scorpionid Cazierius garridoi Armas, 2005. The previously recorded Heteronebo sp. is reexamined and deemed a mislabeled specimen of Heteronebo portoricensis Francke, 1978 from adjacent Puerto Rico. Also, Centruroides mariaorum Santiago-Blay, 2009 is demonstrated to be a junior synonym of C. bani (implying the first demonstrable records of the latter from both Mona Island and Puerto Rico) and Rhopalurus virkkii Santiago-Blay, 2009 is confirmed as a junior synonym of H. abudi. A thorough photographic complement and supplementary ecological and distributional data are provided for every species.

Teruel R, Rivera MJ, Sanchez AJ. The Scorpion Fauna of Mona Island, Puerto Rico (Scorpiones: Buthidae, Scorpionidae). Euscorpius. 2017(250):1-15. [Open Access]