Dietary studies are important for understanding predator-prey relationships and species interactions because they provide information on the trophic resources available to predators and their potential impact on prey populations. We relied on stomach contents of museum specimens and literature records to examine ontogenetic (size-related), sexual, seasonal, and geographic variation in the feeding habits of Sidewinders, Crotalus cerastes. Sidewinders fed primarily on lizards and slightly less frequently on mammals; birds and snakes were rarely consumed. The vast majority of C. cerastes consumed single prey items ingested head-first. Juvenile and adult female Sidewinders consumed lizards and mammals with similar frequency. We observed an ontogenetic shift in feeding patterns of adult male C. cerastes because they included more mammals in their diets, compared with juvenile males. Sidewinders are classic ambush (sit-and-wait) predators and, as predicted by theory, actively foraging lizards and mammals comprise a considerable fraction of their prey. We documented seasonal shifts in the feeding patterns of Sidewinders, with snakes consuming a greater proportion of lizards during early spring and autumn, and a greater percentage of mammals during late spring and summer. This dietary shift likely results from seasonal changes in the activity patterns of C. cerastes, because individuals can be diurnally active during early spring and autumn but are predominantly nocturnal during late spring and summer. Adult male and female Sidewinders from the Mojave and the Sonoran deserts consumed similar proportions of lizards and mammals. Our findings regarding the trophic habits of C. cerastes contribute to our understanding of the ecology of terrestrial, venomous predators.

Environmental temperatures can significantly influence the behavior and physiology of terrestrial ectotherms. Small-bodied terrestrial ectotherms can moderate their body temperatures behaviorally via thermoregulation; however, favorable thermal refuges may be limited across heterogeneous landscapes. In such cases, differences in the thermal environment may generate variation in preferred body temperatures among disparate populations. We tested whether geographic variation in preferred body temperatures existed for the Arizona bark scorpion Centruroides sculpturatus, an arachnid widely distributed across the Sonoran Desert. We predicted that geographic variation in thermal preference would exist between populations from a xeric, low-elevation site in western Arizona (Quartzsite) and a cooler, high-elevation site in eastern Arizona (Pinaleno Mountains). We found that scorpions from the Pinaleno Mountains were smaller in body size and exhibited significantly warmer diurnal body temperatures compared to scorpions from Quartzsite. However, no significant difference was detected in the preferred nocturnal temperatures of scorpions from either locality. Scorpions from the Pinaleno Mountains may have shifted their thermoregulatory patterns and selected warmer temperatures during the day as a way to maximize their exposure to favorable temperatures. Less time with mean temperatures within the preferred range of body temperatures may have also lowered metabolic rates of C sculpturatus in the Pinaleno Mountains, resulting in their smaller female body sizes. The ability of C sculpturatus to adapt to different thermal regimes may reflect variation in a life history trait which has allowed them to thrive and expand their distribution across the American Southwest. (C) 2015 Elsevier Ltd. All rights reserved.

For ectotherms, environmental temperatures influence numerous life history characteristics, and the body temperatures (Tb ) selected by individuals can affect offspring fitness and parental survival. Reproductive trade-offs may therefore ensue for gravid females, because temperatures conducive to embryonic development may compromise females' body condition. We tested whether reproduction influenced thermoregulation in female Arizona Bark Scorpions (Centruroides sculpturatus). We predicted that gravid females select higher Tb and thermoregulate more precisely than nonreproductive females. Gravid C. sculpturatus gain body mass throughout gestation, which exposes larger portions of their pleural membrane, possibly increasing their rates of transcuticular water loss in arid environments. Accordingly, we tested whether gravid C. sculpturatus lose water faster than nonreproductive females. We determined the preferred Tb of female scorpions in a thermal gradient and measured water loss rates using flow-through respirometry. Gravid females preferred significantly higher Tb than nonreproductive females, suggesting that gravid C. sculpturatus alter their thermoregulatory behaviour to promote offspring fitness. However, all scorpions thermoregulated with equal precision, perhaps because arid conditions create selective pressure on all females to thermoregulate effectively. Gravid females lost water faster than nonreproductive animals, indicating that greater exposure of the pleural membrane during gestation enhances the desiccation risk of reproductive females. Our findings suggest that gravid C. sculpturatus experience a trade-off, whereby selection of higher Tb and increased mass during gestation increase females' susceptibility to water loss, and thus their mortality risk. Elucidating the mechanisms that influence thermal preferences may reveal how reproductive trade-offs shape the life history of ectotherms in arid environments.

Two new species of Euscorpius Thorell, 1876 (subgenus Euscorpius s.str.) (Scorpiones: Euscorpiidae) are described based on morphology and the COI DNA barcoding marker: E. deltshevi sp. n. from northern Bulgaria and neighbouring Serbia (formerly reported as E. carpathicus) and E. solegladi sp. n. from southwestern Bulgaria and neighbouring Greece (formerly reported as E. hadzii).

A new species of the vorhiesi group of Vaejovis C.L. Koch, 1836, Vaejovis brysoni sp. n., is described from the Santa Catalina Mountains in southern Arizona. Vaejovis deboerae Ayrey also inhabits this mountain range, making this the first documented case of two vorhiesi group species distributed on the same mountain. When compared to all other vorhiesi group species, Vaejovis brysoni sp. n. is distinct based on several combinations of morphological characters and morphometric ratios.

Background: Life history tradeoffs may result from temporal and physiological constraints intrinsic to an organism. When faced with limited time and energy, compromises occur and these resources are allocated among essential activities, such as body growth, maintenance, foraging, mating, and offspring care. We investigated potential tradeoffs that may occur between reproductive activities and feeding performance in female Arizona Bark Scorpions (Centruroides sculpturatus) by comparing the time taken to capture prey between non-reproductive and reproductive females (gravid females and females exhibiting maternal care, i.e. carrying offspring on their backs).Results: Gravid females were as efficient at catching prey as non-gravid females. To control for variation in the duration of the maternal care period, we removed all offspring from all post-parturient females after 5 days. Brooding females and females 24 hours following offspring removal (FOR) did not successfully capture prey within the 900-second trial period. Twenty-eight days FOR, females caught prey faster than females displaying maternal care and females 24 hours FOR, but were not as efficient at catching prey as non-gravid and gravid females. When pursuing prey, C. sculpturatus exhibiting maternal care used an active foraging strategy more frequently than non-gravid, gravid, and females 28 days FOR. In contrast, non-gravid, gravid, and females 28 days FOR used active and ambush foraging with similar frequency.Conclusions: Our data suggest that reproduction does not significantly reduce the predatory efficiency of gravid C. sculpturatus, and that these females can cope with increasing body mass and the physiological costs of gestation. However, the observation that brooding females and females 24 hours FOR did not catch prey within the trial period indicates that maternal care significantly reduces predatory efficiency in these scorpions. Females 28 days FOR were still not as efficient at catching prey as non-gravid and gravid females, suggesting that reproductive costs extend for at least 4 weeks after the end of the maternal care period. Preferential use of an active foraging strategy by brooding females may increase prey encounter rates, allowing the scorpions to more rapidly replenish energy reserves depleted during reproduction. However, active foraging may be energetically costly and increase predation risk for brooding females. Our findings regarding antagonistic interactions between reproduction and feeding in female C. sculpturatus demonstrate the pervasive nature of reproductive costs for viviparous females, and may provide insight on factors that influence the diversity of reproductive strategies observed in nature.

Arizona bark scorpions (Centruroides sculpturatus Ewing) are commonly found throughout the Sonoran Desert in southwestern North America, and they are well known for being the most venomous scorpion in the United States. Despite their medical significance, C. sculpturatus remains ecologically understudied, and little is known regarding its natural foraging and feeding behaviors. Here, we present the first documented case of C. sculpt uratus feeding on the Sonoran Desert centipede (Scolopendra polymorpha Wood) in the wild.

For ectothermic organisms, environmental temperatures can influence a variety of life history traits. Experimental thermal gradients created in the laboratory are useful tools to examine the thermoregulatory behaviors of these organisms. Here, we provide details on the construction of a novel, cost-effective thermal gradient to study thermoregulatory behaviors in small-bodied nocturnal ectotherms.

A new scorpion species is described from the Inyo Mountains of California (USA). The presence of a strong subaculear spine, along with other characters, places the new species within Wernerius, an incredibly rare genus that until now consisted of only two species. Wernerius inyoensissp. n. can be most easily distinguished from the other members of the genus by smaller adult size, femur and pedipalp dimensions, and differences in hemispermatophore morphology. Previous studies have suggested that the elusive nature of this genus may be attributed to low densities and sporadic surface activity. Herein, we provide another hypothesis, that Wernerius are primarily subterranean. Mitochondrial sequence data are provided for the holotype.

The taxonomic identity of Euscorpius germanus croaticus Di Caporiacco, 1950, described from Croatia and Bosnia, has remained unclear ever since its discovery. We studied the lectotype from the Velebit Mountains as well as new material from Biserujka Cave on Krk Island, Croatia. We reassessed E. g. croaticus using both morphology and DNA barcodes (cox1 sequences) from one of the Biserujka Cave specimens and 15 congeneric species. The resulting DNA phylogeny suggests that E. g. croaticus is not a subspecies of E. germanus. The taxon appears to be a separate lineage, which groups close to subgenus Alpiscorpius but differs from all its members in several morphological characters. We elevate E. g. croaticus to species rank as Euscorpius croaticus Di Caporiacco, 1950, stat. nov., and provide a detailed redescription of both sexes.

Seasonal aphagia (a lack of feeding) can occur if foraging and reproduction occasionally result in conflicting demands on an individual, such that one activity takes precedence over the other. We tested the hypothesis that female and male Crotalus cerastes (Sidewinders) exhibit seasonal aphagia during the reproductive season. We examined the stomach contents of preserved specimens to assess variation in the feeding rates of C. cerastes. Non-reproductive females fed during the early and late stages of the active season, but reproductive females only ate during the first half of the active season. Female Sidewinders fed throughout the early vitellogenic phases of the reproductive cycle, but exhibited a tendency to reduce or cease feeding during the later stages of the cycle (gestation). Prey consumption during early reproductive stages can provide valuable energetic resources for sustaining a female's subsequent breeding activities. However, the physical burden of offspring mass and the concomitant decrease in locomotor efficiency can reduce a female's foraging efficiency in the later phases of the reproductive cycle. Male C. cerastes displayed a trend to feed more frequently during the reproductive season, perhaps because enhancing their energy reserves allows males to travel longer distances and maximize encounter rates with females. The discovery of this intersexual variation in feeding patterns of C. cerastes underscores the importance of descriptive ecological studies to elucidate distinct patterns of life history evolution.