17 November, 2017

The life history of the parthenogenetic scorpion Lychas tricarinatus and some new data on parthenogenesis in Tityus trivittatus

Michael Seiter and Mark Stockman have recently published an article on life history and parthenogenesis in the two buthids Lychas tricarinatus (Simon, 1884) from Odisha province, India and Tityus trivittatus Kraepelin, 1898 from Argentina.

The study clearly demonstrated that Lychas tricarinatus can reproduce without being inseminated by males after observations of captive-born females raised in isolation over three generations. Observations on the entire life cycle of most scorpion species are scarce, and the data shown for Lychas tricarinatus in this study are quite unique.

The Tityus trivittatus used in this study were confirmed to be facultative parthenogenetic, producing both male and female offspring. The capability of a single population to reproduce by sexual as well as by asexual reproduction is probably a strategy to adapt to environmental circumstances enabling genetic variation.

Observations on the entire life cycle of most scorpion species are scarce. Here, we present precise data of the embryonic and postembryonic development for Lychas tricarinatus with additional notes on Tityus trivittatus. By rearing captive-born Lychas tricarinatus specimen from the Odisha province (India) in isolation until maturation, we could show that virgin females gave birth to offspring proving that specimens are capable of parthenogenetic reproduction. Further, we describe an all-female population of Tityus trivittatus from the Corrientes province (Argentina), which originated from a fully bi-sexual population. In addition we describe the ontogenetic development of these two parthenogenetic, buthid scorpions under laboratory conditions. The Dyar’s constant was evaluated for the carapace, metasomal segment V, and the movable finger of the pedipalp among the instars. The calculated growth factor has a total grand average of 1.26. Lychas tricarinatus females reached maturity after 220 days postembryonic development. Moreover, L. tricarinatus females started to reproduce in the 6th or 7th instar and gave birth to an average of 21 neonates after 96 days of embryonic development. Tityus trivittatus matured in the 5th or 6th instar and gave birth after 230 days to an average of 13 neonates.

Seiter M, Stockmann M. The life history of the parthenogenetic scorpion Lychas tricarinatus (Simon, 1884) from Odisha province, India and supplementary notes on Tityus trivittatus Kraepelin, 1898 (Scorpiones, Buthidae). Zoologischer Anzeiger. 2017;270:155-65. [Subscription required for full text]

Thanks to Mark Stockman for sending me this article!

14 November, 2017

Geographic distribution of the genus Mesobuthus in Mongolia

Heddergott and co-workers published a study on the geographic distribution of the genus Mesobuthus Vachon, 1950 (Buthidae) in 2016. I just recently learned about it and want to mention it in the blog as there are very few articles on the scorpion fauna of Mongolia. The results are summed up in the abstract.

In the present study, we surveyed the diversity of scorpions in six provinces of Mongolia (Bayankhongor, Khovd, Dundgovi, Dornogovi, Govisümber and Ömnögovi) between 2001 and 2012. A total of 385 individuals were collected at 17 different sites. In addition to opportunistic sampling, animals were collected after detection with ultraviolet light. Only species from the genus Mesobuthus have been reported from Mongolia thus far. It was possible to confirm the occurrence of the species Mesobuthus eupeus mongolicus and report the presence of M. martensii martensii for the first time. We could not confirm the presence of M. caucasicus przewalskii and suggest that it does not occur in the country, since earlier records originated from present-day China. We provide initial information on the ecology of the two species we identified. Individuals of M. eupeus mongolicus from western Mongolia have a darker pigmentation of the metasomal segments I-IV than individuals from central or southern Mongolia.

Heddergott M, Stubbe M, Stubbe W, Steinbach P, Stubbe A. Geographical Distribution of the Genus Mesobuthus (Scorpiones: Buthidae) in Mongolia. Erforschung biologischer Ressourcen der Mongolei. 2016(13):147-64. [Open Access]

Family Buthidae

Geographic distribution of scorpion envenomations in the USA

Kang and Brooks recently published a epidemiological study on the geographic distribution of scorpion envenomations in the USA in 2010-2015. Most cases were reported from Arizona (57 168), where the infamous Arizona Bark Scorpion (Centruroides sculpturatus Ewing, 1928) is medical important species. Eight other US states also had scorpion envenomations (ranging from 9659 to 906 cases).

Health consequences of scorpion envenomations are also discussed.

Objectives. To determine the geographic distribution of scorpion envenomations in the United States by zip code, with particular attention to the neurotoxic Centruroides sculpturatus (Arizona bark scorpion), for which an antivenom is available.
Methods. We obtained scorpion exposure cases for 2010 to 2015 from the National Poison Data System. Using geographic information systems software, we mapped total exposures and incidence rates for 9 states that reported more than 100 annual calls. We also mapped cases that reported fasciculations and nystagmus (unique to C. sculpturatus among native scorpions).
Results. The highest exposure incidences occurred in Phoenix (up to 677 per 100 000 population) and Tucson (584), both in Arizona. Elsewhere, high incidences were found in El Paso, Texas (213); Oklahoma City (209) and Tulsa (178), Oklahoma; and Las Vegas, Nevada (170). Fasciculations and nystagmus were reported in Arizona and southeastern Nevada, with small numbers in surrounding states, including Utah.
Conclusions. Scorpion exposures occurred at baseline rates throughout many of the southern states, whereas several states reported effects indicative of Arizona bark scorpion envenomation.

Kang AM, Brooks DE. Geographic Distribution of Scorpion Exposures in the United States, 2010-2015. Am J Public Health. 2017;107(12):1958-63. [Subscription required for full text]

03 November, 2017

Scorpion envenomations in southeastern Ecuador

Juan Roman and co-workers have studied scorpion envenomations in rural locations in the Amazonian province of Morona Santiago, southeastern Ecuador. The severity of scorpion stings in this region is reported and the conclusion is that scorpions are a public health problem, especially for young children.

A phylogenetic analysis of the scorpions involved in serious cases were conducted and revealed that these were caused by a species in the Tityus obscurus group (Buthidae). This group contains species responsible for severe envenomations in other areas of the Amazonian Basin. The Ecuadorian species involved is unknown, and will be described as a new species in a future publication.

Scorpion envenoming by species in the genus Tityus is hereby reported from rural locations in the Amazonian province of Morona Santiago, southeastern Ecuador. Twenty envenoming cases (18 patients under 15 years of age) including one death (a 4-year-old male) were recorded at the Macas General Hospital, Morona Santiago, between January 2015 and December 2016 from the counties of Taisha (n =17), Huamboyo (n= 1), Palora (n =1), and Logroño (n =1). An additional fatality from 2014 (a 3-year-old female from Nayantza, Taisha county) is also reported. Leukocytosis and low serum potassium levels were detected in most patients. We observed a significant negative correlation between leukocytosis and hypokalemia. Scorpions involved in three accidents from Macuma, Taisha County, were identified as genetically related to Tityus obscurus from the Brazilian Amazonian region based on comparison of mitochondrial DNA sequences encoding cytochrome oxidase subunit I. These cases, along with previously reported envenoming from northern Manabí, reinforce the notion that scorpionism is a health hazard for children in Ecuador and emphasizes the need to supply effective antivenoms against local species, which are not currently available. The genetic affinity of the Ecuadorian specimens with T. obscurus may underlay toxinological, clinical, and venom antigenic relationships among Amazonian scorpions that deserves further exploration for designing therapeutic strategies to treat scorpionism in the region.

Roman JP, Garcia F, Medina D, Vasquez M, Garcia J, Graham MR, et al. Scorpion envenoming in Morona Santiago, Amazonian Ecuador: Molecular phylogenetics confirms involvement of the Tityus obscurus group. Acta Trop. 2017;178:1-9. [Subscription required for full text]

Thanks to Adolfo Borges and Matthew Graham for both sending me their article!

30 October, 2017

A new species of Physoctonus from southern Amazonia, Brazil

Wilson Lourenco has recently published an article presenting av new species of Physoctonus Mello-Leitao, 1934 (Buthidae) from southern Amazonia, Brazil.

Physoctonus amazonicus Lourenco, 2017

The biogeography of Physoctonus is also discussed.

Further studies on new specimens of the rare genus Physoctonus Mello-Leitão, 1934, lead to the description of a third new species. Until now only Physoctonus debilis (C. L. Koch, 1840) and Physoctonus striatus Esposito et al., 2017, were known from sites located in the caatingas of the north-east region of Brazil. The new species of Physoctonus was collected by the French arachnologist J. Vellard in the Campos do Pará during his field trips back to the 1920/1930, and entrusted to the author in the early 1980s. The populations of P. debilis and P. striatus from north-east Brazil and that of the new species certainly present disrupted distributions. Biogeographical comments on this pattern of distribution are also added.

Lourenco WR. A new species of Physoctonus Mello-Leitão, 1934 from the ‘Campos formations’ of southern Amazonia (Scorpiones, Buthidae). ZooKeys. 2017;711. [Open Access]

Thanks to Venomtech on Twitter for informing me about this article!

Family Buthidae

27 October, 2017

A new vaejovid genus from USA and Mexico

Michael E. Soleglad and co-workers have recently published an article presenting a new genus in the family Vaejovidae from USA and Mexico. Four species have been included in the new genus.

Catalinia Soleglad, Ayrey, Graham & Fet, 2017 (New genus).

Catalinia andreas (Gertsch & Soleglad, 1972) (Previously Pseudouroctonus andreas (Gertsch & Soleglad, 1972)).

Catalinia castanea (Gertsch & Soleglad, 1972) (Raised from subspecies status. Previously Pseudouroctonus minimus castaneus (Gertsch & Soleglad, 1972)).

Catalinia minima (Kraepelin, 1911) (Previously Pseudouroctonus minimus minimus (Kraepelin, 1911)).

Catalinia thompsoni (Gertsch & Soleglad, 1972) (Raised from subspecies status. Previously Pseudouroctonus minimus thompsoni (Gertsch & Soleglad, 1972)).

The habitat and biogeography of the new species is discussed. An identification key is also provided.

Genus Catalinia, gen. nov. (Scorpiones: Vaejovidae) is described from southern California, USA and Baja California, Mexico. The genus is composed of four species formerly placed in Pseudouroctonus: Catalinia minima (Kraepelin, 1911), comb. nov. (type species), C. andreas (Gertsch et Soleglad, 1972), comb. nov., C. castanea (Gertsch et Soleglad, 1972), comb. nov., and C. thompsoni, comb. nov. (Gertsch et Soleglad, 1972). Major diagnostic characters of Catalinia include a carapace with a very weak anterior indentation, a very stout metasoma with little or no tapering from segment I to V, and a mating plug with two partial bases. Evidence is presented suggesting that Catalinia is closely related to the “apacheanus” species group of Pseudouroctonus.

Soleglad ME, Ayrey RF, Graham MR, Fet V. Catalinia, a new scorpion genus from southern California, USA and northern Baja California, Mexico (Scorpiones: Vaejovidae). Euscorpius. 2017(251):1-64. [Open Access]

Family Vaejovidae

06 October, 2017

An update on the medical important scorpions of Mexico

Mexico has a very high diversity of scorpions, but also many medical important species in the genus Centruroides Marx, 1890 (Buthidae). Several of these species have an urban distribution making scorpions a significant health problems in some areas.

Lidia Riano-Umbarila and co-workers have recently published a major study of the medical importance of several Centruroides species based on LD50 tests (a controversial test from a animal welfare and ethics point of view). The article add more knowledge to the list of potential dangerous scorpions species in Mexico (click on the picture to see the species mentioned in this study).

The increment in the number of scorpion envenoming cases in Mexico is mainly associated to the rapid growth of the urban areas, and consequently, to the invasion of natural habitats of these arachnids. On the other hand, there is a great diversity of scorpion species, so it is indispensable to identify those of medical importance, which we now know are many more than the 7-8 previously reported as dangerous to humans. Because different LD50 values have been reported for the venom of the same species, probably due to variations in the experimental conditions used, in this work we determined the LD50 values for the venoms of 13 different species of scorpions using simple but systematic procedures. This information constitutes a referent on the level of toxicity of medically important scorpion species from Mexico and establishes the bases for a more comprehensive assessment of the neutralizing capacity of current and developing antivenoms.

Riano-Umbarila L, Rodriguez-Rodriguez ER, Santibanez-Lopez CE, Guereca L, Uribe-Romero SJ, Gomez-Ramirez IV, et al. Updating knowledge on new medically important scorpion species in Mexico. Toxicon. 2017;138:130-7. [Subscription required for full text]