Fossil of oldest scorpion known to science discovered

Scorpions have been around for a long time and researchers think they were among the first animals to become terrestrial. There is a debate going on whether these old scorpion ancestors were living in water or developed on land. Some think the latter, and that the water living species found developed later.

Andrew J. Wendruff and co-workers have discovered a 430 million years old preserved fossil scorpion from the Waukesha Biota (early Silurian, ca. 437.5–436.5 Ma) of Wisconsin, USA. This is the oldest scorpion fossil ever found. In their interesting article the authors discuss whether Parioscorpio venator, which is the name of grand, grand, grand .........father of today's scorpions, lived on land or in water. Their conclusion is that it probably could live in both environments, similar to today's horseshoe crabs.

Abstract:
Scorpions are among the first animals to have become fully terrestrialised. Their early fossil record is limited, and fundamental questions, including how and when they adapted to life on land, have been difficult to answer. Here we describe a new exceptionally preserved fossil scorpion from the Waukesha Biota (early Silurian, ca. 437.5–436.5 Ma) of Wisconsin, USA. This is the earliest scorpion yet reported, and it shows a combination of primitive marine chelicerate and derived arachnid characteristics. Elements of the circulatory, respiratory, and digestive systems are preserved, and they are essentially indistinguishable from those of present-day scorpions but share similarities with marine relatives. At this early point in arachnid evolution, physiological changes concomitant with the marine-to-terrestrial transition must have occurred but, remarkably, structural change in the circulatory or respiratory systems appear negligible. Whereas there is no unambiguous evidence that this early scorpion was terrestrial, this evidence suggests that ancestral scorpions were likely capable of forays onto land, a behavior similar to that of extant horseshoe crabs.

Reference:
Wendruff AJ, Babcock LE, Wirkner CS, Kluessendorf J, Mikulic DG. A Silurian ancestral scorpion with fossilised internal anatomy illustrating a pathway to arachnid terrestrialisation. Sci Rep. 2020;10(1):14.  [Open Access]

Scorpions use different defensive behavior depending on sex, age and the threat level

Scorpions have developed multiple strategies for the defense against predators ranging from playing dead, running away to fighting back with the use of sting and venom. Interestingly, there seems to be differences in defensive behavior within the same species depending on the sex, age, size/strength of the threat and time of the day.

Andre Lira and co-workers published a study last Fall on the defensive behavior in the scorpion Tityus pusillus Lourenço, 2013 (Buthidae) from Brazil. A plasticity in defensive behavior was observed in this species, seeming to be influenced by the sex, age, diel period, and the body part targeted by the predator.

Abstract:
Differences in gender and age and the balance between aggressive behavior and the ability to escape are fundamental in predator–prey interactions, as well as for survival, foraging, and mating success. We investigated the defensive behavior of the scorpion Tityus pusillus and assessed possible differences in their behavior responses associated with sex, age, and diel period, by simulating a predation threat. Predator attacks were simulated by pressing the telsons with forceps, dropping the animals from a height of 25 cm on a plastic tray, restraining the pincers using large rubber-tipped tweezers, or restricting the prosoma. Tityus pusillus (Buthidae) showed five defensive behaviors: thanatosis, fleeing, stinging, standing still, and tail wagging. The scorpions responded with thanatosis or fleeing when their telsons were restricted. The frequency of these responses varied with sex and diel period. Stinging was the primary behavior response to prosoma restriction in both adults and juveniles while standing still was the most frequently observed behavior response to restraining pincers. These results indicate that the plasticity of defensive behavior in T. pusillus in response to predation is influenced by sex, age, diel period, and the body part targeted by the predator.

Reference:
Lira AFA, Almeida FAF, Albuquerque CMR. Reaction under the risk of predation: effects of age and sexual plasticity on defensive behavior in scorpion Tityus pusillus (Scorpiones: Buthidae). Journal of Ethology. 2019;38(1):13-9. [Subscription required for full text]

Thanks to André for sending me this interesting article that I have been way to slow to read!

An annotated catalogue of the scorpion types held in the Zoological Museum Hamburg - Part I

Scorpions have been collected for several centuries and fortunately many collectors have deposited the specimens into museum collections. The Zoological Museum in Hamburg (ZMH) holds one of the largest and most significant scorpion collections in the world. Lionel Monod and co-workers have now published an annotated catalogue of the ZMH scorpion collections. The current paper covers the parvorder Iurida Soleglad & Fet, 2003. Especially interesting is the documentation of type specimens of 89 species, many illustrated with pictures.

Abstract:
Scorpions have always inspired fear and fascination because of the potency of their venoms. Although this ancient arachnid group is relatively small (ca. 2400 species) and has been continuously studied for the past century, the taxonomy is still in a state of flux and the correct identification of species often remains difficult. With more than 725 species and 9000 specimens, the Zoological Museum in Hamburg (ZMH) holds one of the largest and most significant scorpion collections in the world. This collection also contains many historical types described by Karl Kraepelin in the early 20th century. In order to contribute to a more stable scorpion taxonomy and to assist future scorpion researchers, we present an illustrated and annotated catalogue of the ZMH scorpion collections. The type specimens of 89 species belonging to 10 families are documented, imaged and assessed alongside their primary data. For practical reasons, only the taxa belonging to the parvorder Iurida Soleglad et Fet, 2003 are presented here whilst the Parvorder Buthida Soleglad et Fet, 2003 will be catalogued in a second publication.

Reference:
Monod L, Duperre N, Harms D. An annotated catalogue of the scorpion types (Arachnida, Scorpiones) held in the Zoological Museum Hamburg. Part I: Parvorder Iurida Soleglad & Fet, 2003. Evolutionary Systematics. 2019;3:109-200. [Subscription required for full text]

Thanks to Frantisek Kovarik for informing me about this article!

A redescription of the buthid Tityus estherae from Puerto Rico

Rolando Teruel and co-workers have recently published a redescription of the little known scorpion Tityus estherae Santiago-Blay, 2009 (Buthidae) from Puerto Rico.

Abstract:
The scorpion Tityus estherae Santiago-Blay, 2009, is herein redescribed on the primary basis of adult topotypes of both sexes. This is one of the lesser known scorpions of Puerto Rico due to its deficient original description and scarcity in collections. Moreover, its taxonomic placement within the genus is discussed and its geographic distribution is updated with five new locality records, although it remains known only from the main island.

Reference:
Teruel R, Crespo JD, Sanchez AJ, Rivera MJ. Redescripcion de Tityus estherae Santiago-Blay, 2009 (Scorpiones: Buthidae) , escorpion endemico de Puerto Rico. Boletin de Grupo de Sistematica y Ecologia de Artropodos Caribeños. 2019;3:1-15. [Available in Research gate]

Thanks to Rolando for sending me their article!

Family Buthidae

A redescription of Euscorpiops sejnai from Vietnam

Thi-Hang Tran and co-workers have recently published a redescription of Euscorpiops sejnai (Kovařík, 2000) (Euscorpiidae) from Vietnam.

Abstract:
Euscorpiops sejnai (Kovařík, 2000), a species belonging to the family Scorpiopidae Kraepelin, 1905, is redescribed based on two topotype specimens, one male and one female, collected in the type locality, the Bach Ma National Park in Vietnam. This contribution is part of a global inventory survey of the Vietnamese scorpion fauna conducted by the first author (T. H.T), in connection with the preparation of a doctoral thesis.

Reference:
Tran T-H, Hoang T-N, Pham D-S, Lourenco WR. A short contribution to the knowledge of Euscorpiops sejnai (Kovařík, 2000), described from Vietnam (Scorpiones: Scorpiopidae). Revista Iberica de Arachnologia. 2019(35):29-32.

Thanks to Frantisek Kovarik for informing me about this article!

Family Euscorpiidae

A new species of Ananteris from Central Brazil

Wilson Lourenco and Paulo Motta have recently published an article describing a new species of Ananteris Thorell, 1891 (Buthidae) from Central Brazil.

Ananteris carrasco Lourenco & Motta, 2019

Abstract:
A new species of the genus Ananteris Thorell is described from the Cocos region, in the State of Bahia, in Brazil, based on two adult specimens, one male and one female. Ananteris carrasco sp. n. is the second species to be described from the Cocos region, constituting a new case of sympatry among species of the genus Ananteris: Ananteris carrasco sp. n. is sympatric with Ananteris evellynae Lourenço, 2004.

Reference:
Lourenco WR, Motta PC. The genus Ananteris Thorell, 1891 (scorpiones: Buthidae) in central Brazil, with description of one new species. Revista Iberica de Arachnologia. 2019(35):9-13.

Thanks to Frantisek Kovarik for informing me about this paper!

Family Buthidae

A review of the genus Megacormus with the description of a new species from Mexico

A Happy New Year to all the readers of The Scorpion Files!

Frantisek Kovarik published a revision of the Mexican genus Megacormus Karsch, 1881 (Euscorpiidae) just before Christmas. In the revision a new species is described from Mexico.

Megacormus franckei Kovarik, 2019

The article has an identification key for the genus and color pictures of all the species in the genus.

Abstract:
Megacormus franckei sp. n. from Mexico is described and compared with all other species of the genus. Additional information is provided on the morphology, taxonomy and localities of genus Megacormus, mainly through color photographs of live and preserved specimens of all Megacormus species, as well as their habitats. Included is a key for all six known species of the genus Megacormus.

Reference:
Kovarik F. Review of Megacormus Karsch, 1881, with description of a new species (Scorpiones: Euscorpiidae). Euscorpius. 2019(296):1-46. [Open Access]

Family Euscorpiidae