Offspring growth and development in two buthid scorpions from Azerbaijan

Growth and biological development in scorpions vary between species and their habitat, climate and feeding ecology. Nizami E. Novruzov has recently published a laboratory study of the above in the two buthid species Olivierus caucasicus (Nordmann, 1840) and Mesobuthus eupeus (C.L. Koch, 1839) from Azerbaijan. See abstract and article for details.

Abstract:
The main aspects of offspring growth in two scorpion species – Mesobuthus eupeus and Olivierus caucasicus were studied. The entire reproductive cycle – mating, pregnancy of females, birth of the offspring and their growth until adulthood – took place in laboratory conditions. The duration, rate, and intensity of growth, as well as the dynamics of body weight changes and some metric traits during post-embryonic ontogenesis were studied. The growth of young scorpions was uneven, with growth periods of varying lengths: from larva to third molt – an average of 6.2 months, from the fourth molt to the sixth (imago) – an average of 12.6 months (M. eupeus); and an average of 7.7 and 14.1 months (O. caucasicus). By duration of development, M. eupeus nymphs were ahead of O. caucasicus nymphs: on average by 9.2±2.8 days in early post-larval ontogenesis and by 15.0±3.5 days in late post larval ontogenesis. Of the entire growth cycle, 4/5 occurred during molting, the remaining 1/5 occurred in the periods between molting. Species-specific and sex-specific differences in the dynamics of changes in linear characters and body weight were identified. Sexual dimorphism was also evident in faster development, a greater number of molts, and a longer lifespan in females compared to males. Changes in growth rate and intensity tended to increase at the beginning of development and decrease at the end. Nymphs of both species also showed some decrease in growth rate and weight gain during periods of no feeding activity before molting and during periods chronologically corresponding to their natural diapause in the wild.

Reference:
Novruzov NE. Comparative dynamics of offspring growth in Mesobuthus eupeus (C.L. Koch, 1839) and Olivierus caucasicus (Nordmann, 1840) (Scorpiones: Buthidae). Serket. 2026;21(2):158–74. [Open Access]

Thanks to Hisham El-Hennaway for sending me the article! 

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]

Survival strategies of first-instar scorplings of Olivierus martensii

 

Ecdysis (molting, changing skin) is the way that scorpions and many other arthropods grow. This is a risky part of an young scorpions life, especially during the first molts. Yiyuan Guo and co-workers have recently published a study on the strategies used by first-instar scorplings of Olivierus martensii (Karsch, 1879) (Buthidae) to optimize survival (the article use the old name for this species, Mesobuthus martensii). 

The study shows that newborn scorpions exhibit special aggregate molting behavior, which increases their chances of survival. This aggregating behavior makes it easier for the mother scorpion to keep the scorplings on her back, even though this behavior is also observed when scorplings molt away from the mother's back. The cooperative nature of aggregate molting in first-instars combined with staying on the mother's back and in her care is probably an essential role in increasing the survival of the young scorplings.

Abstract:
Ecdysis is a well-known developmental feature among arthropods. Because the aggregate and synchronous molting of first-instar scorpions is markedly different from the common independent molting behavior of older scorpions and most arthropods, knowledge on the biological benefits of the unusual behavior of first-instar scorpions remain limited. Before the molting of newborn scorpions, their mothers exhibited a remarkable ability to efficiently locate the fallen offspring and help them climb onto their back, which was supported by strong maternal behavior because they climbed more swiftly than the 7-day postpartum scorpions. Most newborn scorpions molted and survived on the mother’s back, with a survival rate of approximately 100%, and most newborn scorpions survived via aggregate molting behavior on sand in the absence of mothers (89.83% ± 1.91%). The important role of the mother scorpion was further highlighted in mothers with one to five first-instar scorpions.While all first-instar scorpions individually or reciprocally molted and survived on the mother’s back, only 52.00% ± 7.14% to 79.20% ± 4.24% of newborn scorpions isolated from the mother could individually or reciprocally molt and survive on the sand, and the aggregated states of first-instar scorpions strengthened as their numbers on sand increased before molting. These results highlight collaborative molting as an evolutionary driving force for newborn scorpions. Taken together, both maternal care and collaborative aggregate molting behavior enhanced the survival of first-instar scorpions before and after molting, and these benefits for first-instar scorpions play essential and evolutionary roles in scorpion survival.

Reference:
Guo Y, Li S, Lu S, Wang X, Cao Z, Wu Y. Special Survival Strategy of First-Instar Scorpions Revealed by Synchronous Molting Behavior from Social Facilitation of Maternal Care and Reciprocal Aggregation. Insects. 2024;15(9). [Open Access]

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!

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]

New data on distribution and biology of the North African Lissothus occidentalis

Mark Stockmann and co-workers recently published an article with new data on the North African buthid Lissothus occidentalis Vachon, 1950. See abstract for a summary of the new data. The article has several color photos, showing both live specimens and their natural habitats.

Abstract:
Genus Lissothus Vachon, 1948 represented by L. occidentalis Vachon, 1950 is reported for the first time from four localities in Morocco and the Western Sahara. We provide a revised diagnosis of L. occidentalis, fully com-plemented with color photos of live and preserved specimens. Hemispermatophore is also illustrated and described in detail. Furthermore, we describe aspects of the ecology of this species, and provide photos of collection sites and habitats. We also report on the reproductive biology of this species based on captive breeding and rearing. and provide the first envenomation report for the species.

Reference:
Stockmann M, Turiel C, Althoff F, Lowe G, Kovarik F. First report of Lissothus occidentalis Vachon, 1950 (Scorpiones: Buthidae) from Morocco and Western Sahara, with notes on ecology and captive breeding. Euscorpius. 2016(235):1-12. [Open Access]

Reproduction and life history in Tityus pusillus

Cleide Albuquerque and Andre Lira have recently published a study on reproductive strategies and life history in the buthid Tityus pusillus Poocock, 1893, the most abundant and widespread scorpion species
in the northeast Brazilian Atlantic Forest.

Two different reproductive strategies were identified in addition to the deferred reproduction previously recorded for this species. The evolution of the reproductive strategies observed is discussed.

Abstract:
A remarkable diversity of life history strategies has evolved among species for achieving reproductive success, including adaptive growth, protandry, iteroparity, and extra molting. Here, we report on the reproductive strategies of the litter-dwelling scorpion, Tityus (Archaeotityus) pusillus, the most abundant and widespread scorpion species in the Atlantic Forest of northeastern Brazil. We observed both iteroparity and protandry reproductive strategies in this species. Females were competent to produce up to three broods after a single insemination, and no correlation between female size and litter size was observed. Most males reached adulthood 1 month before females following four molts, characterizing protandry. Nevertheless, an extra molt was observed to occur in some males (n = 4) and females (n = 1). These findings highlight the life history traits of T. (A.) pusillus, which may imply in reproductive success and adaptation to changes in environmental conditions.

Reference:
Albuquerque CMRd, Lira AFdA. Insights into reproductive strategies of Tityus (Archaeotityus) pusillus Pocock, 1893 (Scorpiones, Buthidae). Comptes Rendus - Biologies. 2016;In Press.[Subscription required for full text]

Thanks to Andre Lira for sending me his article!

Clutch size in the "vorhiesi" group of the genus Vaejovis

Richard Ayrey has recently published an interesting article documenting the clutch size for the 12 species in the "vorhiesi" group of the genus Vaejovis C. L. koch, 1836 (Vaejovidae). The article has color pictures of females with scorplings for many of the species.

Abstract:
A total of 2,287 newborn scorpions were counted and photographed on 100 females of all 12 described species of  the  “vorhiesi”  group  of  the  genus  Vaejovis  (Scorpiones:  Vaejovidae)  found  in  Arizona,  USA,  and  several  undescribed species. Average clutch size for the “vorhiesi” group and for each individual species is reported. The  data clearly shows that the larger species have more young, per parturition, than the smaller species. Representative  photographs are presented for each species discussed.

Reference:
Ayrey RF. Reproduction and birth in the “Vorhiesi” group of the genus Vaejovis (Scorpiones: Vaejovidae). Part I. Clutch size. Euscorpius. 2013 (166):1-15. [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!

Ovulation, fertilization and embryonic development in scorpions - a partial review

Yesterday I blogged about a new and interesting review on scorpion reproduction by professor Michael Warburg. Today, professor Warburg sent me another new review article that he as recently published on scorpion reproduction. The main topics of this publication is ovulation, fertilization and embryonic development in scorpions.

Abstract:
Ovulation, fertilization and both normal and arrested embryonic developments in scorpions, are reviewed and discussed. The importance of all three aspects in scorpion reproduction is discussed from both an evolutionary and an ecological outlook. The number of embryos varies within and among scorpion species and is not related to the female’s mass prior to parturition. There is a certain loss in embryo numbers and not all of them will become juveniles. The significance of this loss is discussed, and future avenues of research are suggested.

Reference:
Warburg MR. Ovulation, fertilization and embryonic development in scorpions: a partial review. African Entomology. 2012;20(1):60-8. [Subscription required for fulltext]

Thanks to professor Warburg for sending me this paper!

A review on scorpion reproduction

We still do not know enough about scorpion reproduction. Professor Michael Warburg is one of the leading experts on this topic and he has previously published several important papers on this topic (e.g. the recent The Female reproduction system in scorpions - a review and A review of scorpion reproductive strategies).

This time he has published a very interesting paper reviewing and discussing mating, insemination, gestation, modes of reproduction, parurition, breeding season and birth in scorpions. Professor Warburg also discuss future research of scorpion reproduction in this paper.

Abstract:
Although scorpions are an ancient group their method of reproduction is rather complex and poorly studied. This review aims at clarifying some of the aspects of their reproduction that are important for understanding the reproductive ecology of other arthropods, including insects. The following aspects of scorpion reproduction are discussed and reviewed: mating, insemination, fertilization, gestation, parturition and birth. The onset of gestation and its duration are difficult to determine as both depend on the time of fertilization, for which there are no accurate estimates. There are only a few records of the time between birth and emergence of a larva from the maternal envelope in apoikogenic scorpions, which is important for a better understanding of ovoviviparity. All these questions are important as the answers will greatly enhance our understanding of the population ecology of scorpions in terms of the recruitment rates of cohorts and their chances of survival.

Reference:
Warburg MR. Pre- and post-parturial aspects of scorpion reproduction. European Journal of Entomology. 2012;109:139-46.

Thanks to Matt Simon for informing me about this paper and to professor Warburg for sending it to me!

A review of scorpion reproductive strategies

Michael Warburg has recently published an interesting review on scorpion reproductive strategies. In addition to reviewing the existing knowledge on this topic, he also makes suggestions about future research on this topic.

Abstract:
Most scorpion species are iteroparous, breeding more than once during their life. Some of these species are parthenogenetic. The other reproductive strategy (RS) semelparity, when scorpions breed only a single time during their life, is rare and has been documented only once. The mass allocated by the female to produce either a litter or a single offspring is the reproductive allocation (RA). It is difficult to calculate RA since the difference in female mass before and after parturition is difficult to obtain. In addition, the litter size is hardly ever accurate because of maternal cannibalism. An attempt was made to calculate RA in Nebo hierichonticus (E. Simon, 1872). Based on litter size, on breeding frequency and on longevity of the female, it is possible to estimate the reproductive potential (RP). These aspects of scorpion reproduction are reviewed and the difficulties involved in this study are discussed.

Reference:
Warburg MR. Scorpion reproductive strategies, allocation and potential; A partial review. European Journal of Entomology. 2011;108(2):173-81. [Free fulltext]

Observations on newborn Opisthacanthus maculatus from Madagascar

Luc Ross has published a study on the post-birth behavior of newborn Opisthacanthus maculatus Lourenco & Goodman, 2006 (Hemiscorpiidae).

Abstract:
Observational data on the early development and post-birth behavior of a single litter of the Malagasy endemic scorpion, Opisthacanthus maculatus Lourenço & Goodman, 2006 (Liochelidae) is reported for the first time. A single female gave birth to a litter of 11 offspring during a 10 hour period of parturition. The young
molted to the second-instar within a 14 day period. After an additional 10—12 day period, the young dispersed from the maternal female. This is the first report of post-birth behavior for a Malagasy endemic Opisthacanthus species.

Reference:
Ross LK. Observations on newborn Opisthacanthus maculatus Lourenco & Goodman, 2006 (Scorpiones, Liochelidae) from Madagascar. Revista Iberica de Arachnologia. 2010;18:123-7.

Family Hemiscorpiidae

New data on larval orientation in Vaejovis

It is well known that female scorpions carry first instar and pre-dispersal second instars scorplings on their back. The orientation of the instar on the female's back vary. In the genus Vaejovis, scorplings have been arranged in a longitudinal pattern of orientation.

Luc Ross now reports of a random larval orientation in Vaejovis confusus (Vaejovidae), which is the first in the genus. The paper also presents previously unreported cases of dorsal orientation in Vaejovidae.

A table with all data on larval orientation of Vaejovidae is presented.

Abstract:


Reference:
Ross LK. First report of random larval orientation in the genus Vaejovis C. L. Koch, 1836 (Scorpiones: Vaejovidae). Boletin Sociedad Entomológica Aragonesa. 2009 (45):531-2.

Family Vaejovidae