The postembryonic development of Centruroides ochraceus from Mexico

 

Happy New Year!

Wilson Lourenco and Eric Ythier have recently published some old observations of postembryonic development of Centruroides ochraceus (Pocock, 1898) (Buthidae) from Yucatan, Mexico. It is also suggested that parthenogenesis exists in this species.

Abstract:
Since general data on the biology of scorpions remain rare, we propose in this note some results on the postembryonic development of the buthid scorpion Centruroides ochraceus (Pocock, 1898), species distributed in the Yucatan peninsula, Mexico. The results were originally observed almost 40 years ago, based on some specimens collected by the senior author. A possible case of parthenogenesis is also suggested for this species.

Reference:
Lourenço WR, Ythier E. The postembryonic development of Centruroides ochraceus (Pocock, 1898) from Yucatan, Mexico (Scorpiones: Buthidae), with comments on parthenogenesis. Revista Iberica de Arachnologia. 2024(45):119-22. [Full text supplied by author]

Fitness differences between parthenogenetic litters of the parthenogenetic scorpion Tityus stigmurus

 

We often think that parthenogenetic reproduction produces clones that are identical in most ways. But there are non-genetical factors that may cause variations even though the organism is living in the same, stable environment. One example of this is maternal age's impact on different parthenogenetic litters.

Welton Dionisio-da-Silva and co-workers have recently pulished a study on non-Mendelian variation on parthenogenetic litters in the medical important species Tityus stigmurus (Thorell, 1876) (Buthidae). Their results indicate that T. stigmurus females allocated nutrient resources to maximize litter size rather than developmental fitness in subsequent litters. See abstract and article for more details.

I can add that knowledge of reproduction and life history of this scorpion is important as it is a medical important species that thrive in urban areas with high risk of human contact. 

Abstract:
Clonal lineages in similar environments may be influenced by non-Mendelian inheritance, such as maternal age effects and developmental instabilities. These mechanisms may affect the developmental fitness of parthenogenetic litters. In this study, the scorpion Tityus stigmurus (Thorell, 1876) was used to analyze the effects of non-Mendelian variation on parthenogenetic litters. A total of 75 juveniles from five females were reared under the same controlled conditions, while their development was observed and evaluated through differences in offspring fitness traits (litter size, prosoma size, developmental time, and mortality) between the litters. First and second litters had a similar litter size, although second litters exhibited longer developmental time in the early instar stages (second and third) than first litters. These results indicate that T. stigmurus females allocated nutrient resources to maximize litter size rather than developmental fitness in subsequent litters. Differences in developmental time found in early instars but not in late instars may have occurred as a result of stochastic developmental variations in young individuals. Such variation in duration of development has the potential to influence survival of juveniles in natural environments because individuals that grow faster may avoid large predators and consume larger prey, compared to those that do not.

Reference:
Dionisio-da-Silva W, Albuquerque CMR, Lira AFA. Fitness differences between parthenogenetic litters of the synanthropic scorpion Tityus stigmurus (Scorpiones: Buthidae). Animal Biology. 2022;72:435-46. [Subscription required for full text]

Thanks to Welton Dionisio-da-Silva for sending me their article!

An update on the infamous, medical important buthid Tityus serrulatus from Brazil

 

Among the most dangerous scorpions in the word, the genus Tityus C. L. Koch, 1836 (Buthidae) from South America has some of the most potent species. Bad guy number one in the genus is probably the Brazilian species Tityus serrulatus Lutz & Mello, 1922. The species is well known for its medical potency, but also for its rapid geographical expansion, occurrence in urban habitats and for its large populations of asexual (parthenogentic) members.

Wilson Lourenco has recently published an update on the historical, geographical and ecological aspects connected to this important species. The article also discuss the status of other species in the genus.

Abstract:
A synopsis on the historical, geographical and ecological aspects related to the most conspicuous scorpion species of the genus Tityus known from Brazil is proposed. Tityus serrulatus Lutz & Mello, 1922 was described precisely one century ago, nevertheless many questions related to its ecological adaptations and geographical expansion remain without a precise response. This species, well known for its infamous reputation of noxious species, is also known for its capacity to reproduce asexually, by parthenogenesis. Although the individuals of a given population are considered clones, a new hypothesis could  suggest the occurrence of mutations within isolated individuals, leading to distinct subpopulations that could present better phenotypic performances in ecological habitats distinct from those of the original area of distribution of the species.

Reference:
Lourenço WR. Back to Tityus serrulatus Lutz & Mello, 1922 (Scorpiones: Buthidae): new comments about an old species. J Venom Anim Toxins Incl Trop Dis. 2022;28:e20220016. [Open Access]

Family Buthidae

Courtship behavior of the parthenogenetic scorpion Tityus stigmurus from Brazil

 

Most scorpions have sexual reproduction, but a few species seem to have parthenogensis as the main method for reproduction and in these species males are rare. We know very little about the courtship behavior in the species that can reproduce by either method.

Stênio Foerster and co-workers have recently published a study of the courtship repertoire of the Brazilian, parthenogenetic scorpion Tityus stigmurus (Thorell, 1876) (Buthidae), which have sexual populations distributed throughout northeastern Brazil.

Overall, the reproductive repertoire of T. stigmurus was similar to that of other non-parthenogentic scorpions.

Abstract:
Scorpions can adopt different reproductive strategies (e.g., sexual or parthenogenesis) depending on the environmental conditions. In this study, we described the courtship repertoire of the parthenogenetic scorpion Tityus stigmurus, a species with inconspicuous sexual populations distributed throughout northeastern Brazil. Specimens of both sexes (10 male, 10 female) were obtained from field expeditions in three locations in northeastern Brazil and were paired under laboratory conditions in an intrapopulation design. All observations were conducted at night using red light positioned above an experimental arena. From the 10 courtship interactions observed in this study, only one pair successfully completed the reproductive repertoire that included the insemination process. The incomplete interactions were abruptly terminated by the females immediately after deposition of the spermatophore. Overall, the reproductive repertoire of T. stigmurus was similar to that of other scorpions, especially its congeners, possibly because this reproductive behavior emerged at a basal point in the evolution of scorpions. The acquisition of new insights into the reproductive biology of different scorpion species may improve the theoretical background for applications ranging from evolutionary biology to public health strategies.

Reference:
Foerster SIA, Dionisio-da-Silva W, dos Santos AB, de Albuquerque CMR, de Araújo Lira AF. Notes on the courtship behavior of the parthenogenetic scorpion Tityus stigmurus. Acta Arachnologica. 2021;70(2):83-6. [Open Access]

Thanks to Andre Lira for sending me their article!

The genus Hottentotta may have become established in Spain

 

Non-native species have been reported from many countries, but most of these are introduced and usually have not become established a a viable population. Spain are known for several introduced species, most notable the buthid Centruroides gracilis (Latreille, 1804) in the island Tenerife that seems to be an established population.

Rolando Teruel and Carlos Turiel now report of several findings of the African species Hottentotta hottentotta (Fabricius, 1787) (Buthidae) from northwestern Spain. The independent findings of three live, female specimens from two different locations may suggest that this species have become established in this part of Spain. 

Hottentotta hottentotta is an ideal candidate for colonization as its widespread distribution in tropical West Africa indicates a species with high ecological plasticity. In addition, the species is known for the ability to asexual reproduction by parthenogenesis.

It will be interesting to see if there will be further findings that can confirm the occurrence of this genus in Spain and in Europe.

Abstract:
The present note reports on the occurrence of the buthid scorpion Hottentotta hottentotta (Fabricius, 1787) at two localities in north-western Spain: Nieves (Galicia) and Gijon (Asturias). This species is markedly synanthropic and native to western Africa, where it is widespread and consists largely of parthenogentic populations. The finding of three live adult females independently at two different localities , but within the same geographical region (The Iberian northwest), suggests that this species could have successfully become established here. Spain now harbours four introduced species: one confirmed as established and two others seemingly so as well.

Reference:
Teruel R, Turiel C. "New kid on the block": The West African scorpion Hottentotta hottentotta (Frabricius, 1787) (Scorpiones: Buthidae) may have become established in Spain. Revista Iberica de Arachnologia. 2021(39):107-9.

Thanks to Rolando, Carlos and Luis for all sending me this article!

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.

Abstract:
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.

Reference:
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!

First report of parthenogenesis in the family Vaejovidae.

Richard Ayrey described Serradigitus miscionei (Vaejovidae) in 2011, but was not able to find any males. Now he has examined 187 specimens and all turned out to be females. In 15 examined broods, all 2nd instars were found to be females.This provides a strong evidence that this species reproduces by thelytokous parthenogenesis (has all-female broods).

This is the first reported case of parthenogenesis in the family Vaejovidae.

Abstract:
Thelytokous parthenogenesis (all-female broods) is strongly suggested for the vaejovid species Serradigitus miscionei (Vaejovidae) from southern Arizona, USA. This conclusion is based on the examination of 187 specimens and 15 broods, all determined as females.

Reference:
Ayrey RF. Serradigitus miscionei, the First Vaejovid Scorpion to Exhibit Parthenogenesis. Euscorpius. 2017(241):1-7. [Open Access]

Parthenogenetic reproduction reported for the buthid Pseudolychas ochraceus

Partogenetic reproduction has been reported for several scorpion species, but not all observations have been made under controlled circumstances. Francke (2008) proposed that the parturition of a captive isolated female collected immature in the wild is the minimal evidence required to conclude that a scorpion species is parthenogenetic.

Seiter, Schramm and Barthel have now published a research note demonstrating true parthenogenesis in the South African buthid Pseudolychas ochraceus (Hirst, 1911).

Abstract:
Of all scorpion species described to date, only a small fraction are known to reproduce without fertilization by a male, instead producing offspring by parthenogenesis. Here we show that isolated females of the buthid Pseudolychas ochraceus (Hirst, 1911) are capable of parthenogenetic reproduction and we provide data on the postembryonic growth of this species.

Reference:
Seiter M, Schramm FD, Barthel A. The South African scorpion Pseudolychas ochraceus (Hirst, 1911) (Scorpiones: Buthidae) can reproduce by parthenogenesis. Journal of Arachnology. 2016; 44: 85-87. [Subscription required for full text]

Updated info on the males of three species of Tityus

The description of males in population of scorpions is an important contribution, not only as regards taxonomic knowledge of the species, but also to enable understanding of its reproductive strategy. In a recent paper, Maria Dulcineia Sales dos Santos and co-workers describe the male of T. kuryi Lourenco, 1997 for the first time and report new records of T. serrulatus and T. stigmurus males, widening the known distribution of their sexual populations. The latter two species also have several populations in Brazil that are parthenogenetic.

Abstract:
The male of Tityus kuryi Lourenço, 1997 is described for the first time. Despite being very similar to the female, the male presents more robust metasomal segments. Additionally, the distribution of the sexual populations of another two species of the T. stigmurus complex is reported herein: T. serrulatus Lutz & Mello, 1922 and T. stigmurus (Thorell, 1877). Males of T. serrulatus were, until now, restricted to the Minas Gerais State (Southwestern region of Brazil), and with new records reported here, its known distribution now encompasses the Northeastern region of Brazil. Males of T. stigmurus were previously recorded only for two municipalities in the State of Bahia, and here we present eight new records for Bahia State and one for Pernambuco State. We present a key to related species of the T. stigmurus complex based on morphology and coloration pattern.

Reference:
Dos Santos MD, Porto TJ, Lira-da-Silva RM, Brazil TK. Description of the male of Tityus kuryi Lourenco, 1997 and notes about males of Tityus stigmurus (Thorell, 1877) and Tityus serrulatus Lutz & Mello, 1922 (Scorpiones, Buthidae). Zookeys. 2014 (435):49-61. [Free full text]

Development and reproduction in two species of Tityus

Michael Seiter has recently published a paper investigating the juvenile instars and reproductive biology of the two neotropical species Tityus confluens Borelli, 1899 and T. ocelote (Francke & Stockwell, 1987) (Buthidae).

Main results are available in the abstract below, but I will mention that this work confirms parthenogenesis (and no males for three generations) for Tityus confluens.

Abstract:
The life cycle and postembryonic development of Tityus confluens Borelli, 1899 and Tityus ocelote (Francke & Stockwell, 1987) are for the first time described. The duration of embryonic development was estimated to range from 86 to 184 (N = 11) days in T. confluens and 68 to 72 (N = 4) days in T. ocelote. The molts between juvenile instars and adult stage took place at the average ages of 5, 38, 106 and 157 days in T. confluens and 4, 60, 62 and 97 days in T. ocelote. Compared with other species of the family Buthidae in the same range of size the figures are similar. The morphometric growth factor (Dyar’s constant) are higher than those observed for other scorpions of the genus Tityus of the same size. Parthenogenesis is confirmed for T. confluens based on captive bred females raised in isolation since offspring (N = 156). No males were observed over a period of 3 generations.

Reference:
Seiter M. Developmental stages and reproductive biology in Tityus confluens borelli, 1899 and Tityus ocelote (Francke & Stockwell, 1987) (Scorpiones, Buthidae). Revista Iberica de Arachnologia. 2012 (21):113-8.

Thanks to Michael Seiter for sending me his paper!

Parthenogenesis confirmed for Tityus stigmurus

Luc Ross has published a study confirming parthenogenesis in the medical important species Tityus stigmurus (Thorell, 1876) (Buthidae). This is important knowledge as this species has large populations in urbanized areas in several regions in Brazil. T. stigmurus is considered among the three most toxic species in the genus and the presence of parthenogenetic populations allows rapid colonization, dispersion and population growth, making this an important factor in public health.

Abstract:
Parthenogenesis (asexuality) or reproduction of viable offspring without fertilization by a male gamete is confirmed for the medically significant, synanthropic scorpion Tityus (Tityus) stigmurus (Thorell, 1876) (Buthidae), based on the litters of four virgin females (62.3–64.6 mm) reared in isolation in the laboratory since birth. Mature females were capable of producing initial litters of 10–21 thelytokous offspring each; 93–117 days post-maturation. While Tityus stigmurus has been historically considered a parthenogenetic species in the pertinent literature, the present contribution is the first to demonstrate and confirm thelytokous parthenogenesis in this species.

Reference:
Ross LK. Confirmation of parthenogenesis in the medical significant, synthropic scorpion Tityus stigmurus (Thorell, 1876) (Scorpiones: Buthidae). Revista Iberica de Arachnologia. 2010;18:115-21.

Thanks to Luc Ross for sending me this paper!

Family Buthidae

Inter- and intrapopulational genetic variability of Tityus serrulatus

Ronaldo Carvalho Scholte and co-workers have recently published a study on the genetic variability of different populations of Tityus serrulatus (Buthidae) in Brazil. T. serrulatus is a parthenogentic species of medical importance that has an increasing distribution in Brazil, and knowledge of its genetics and reproductive mechanisms is of great interest.

Abstract:
In Brazil, there are near 20 genera and almost 120 species of scorpions of which 95% reproduce sexually. Parthenogenetic reproduction, however,may also take place. To gain insight into useful molecularmarkers in parthenogenetic scorpion species, we studied DNA polymorphism using two molecular approaches: simple sequence repeat anchored polymerase chain reaction (SSR-PCR) and sequencing of the cytochrome C oxidase subunit I of the mitochondrial genome,mtDNA(COXI), of Tityus serrulatus. Three different groups were used: group 1, composed of 1 female and 14 descendants; group 2 with 1 female and 17 descendants, both from the city of Uberlândia, State of Minas Gerais (MG), Brazil, and the third group that consisted of three adult scorpions from the city of Belo Horizonte, MG.

The profiles generated by SSR-PCR were identical for all specimens, while partial sequencing of COXI showed the presence of SNPs. After aligning COXI contigs, one of the groups presented 18 SNPs and the second 8 SNPs. The two groups were differentiated by two diagnostic SNPs. We did not find evidence of mitochondrial recombination.

The results are in agreement with the parthenogenetic mode of reproduction of this species and sequencing of the COXI gene enabled the separation of scorpions groups.

Reference:
Scholte RGC, Caldeira RL, Simoes MCM, Stutz WH, Silva LL, Carvalho OD, et al. Inter- and intrapopulational genetic variability of Tityus serrulatus (Scorpiones, Buthidae). Acta Trop. 2009 Nov;112(2):97-100. [Subscription required for fulltext]

Family buthidae

Parthenogenesis in scorpions - new review article

Professor Wilson Lourenco has published an interesting review on parthenogenesis in scorpions. This is a rare phenomenon in arachnids, but so far parthenogenesis has been reported in 12 scorpion species:

Tityus columbianus (Thorell, 1876)
T. metuendus Pocock, 1897
T. serrulatus Lutz & Mello, 1922
Tityus sp. [New sp. not yet described - info in the article]
T. stigmurus (Thorell, 1876)
T. trivittatus Kraepelin, 1898
T. uruguayensis Borelli, 1901
Ananteris coineaui Lourenco, 1982
Centruroides gracilis (Latreille, 1804)
Hottentotta caboverdensis Lourenco & Ythier, 2006
H. hottentotta (Fabricius, 1787)
Liocheles australasiae (Fabricius, 1775)

Professor Lourenco discuss the general theory behind parthenogenesis in animals, compare these to the situation seen in scorpions, and finally presents some selected examples of geographic parthenogenesis in scorpions.

Reference:
Lourenco WR. Parthenogenesis in scorpions: Some history - new data. Journal of Venomous Animals and Toxins Including Tropical Diseases. 2008;14(1):19-44. [Fulltext freely available, but issue 1, 2008 has not been published on the website yet]