Two new arthropod toxins purified from the venom of the Mexican scorpion Centruroides nigrescens

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  Two new arthropod toxins purified from the venom of the Mexican scorpion Centruroides nigrescens Abstract The venom of the slender black scorpion Centruroides nigrescens , from the State of Guerrero México, was fractionated by Sephadex G–50 gel filtration, followed by carboxymethyl cellulose ion separation and high–performance liquid chromatography, permitting to obtain two new peptides toxic to arthropods. The estimate LD 50 of the soluble venom for the insect Acheta domesticus was 11.1 μg/g body weight, and for the arthropod Armadillidium vulgare was 61.1 μg body weight . The amino acid sequence of toxin Cnige1 (toxic to A. domesticus and A. vulgare ) contains 65 amino acids, with a molecular mass of 7273.37 mass units, whereas toxin Cnige2, toxic to A. domesticus , contains 68 amino acids, with a molecular mass of 7548.81 units. Both peptides are well packed, containing 8 cysteines, which in the native venoms are forming 4 disulfide bridges each. The amino acid sequences f...

Surface climate and cave morphology predict the distribution and behavior of the troglobitic spider Tisentnops mineiro (Araneae: Caponiidae)

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Surface climate and cave morphology predict the distribution and behavior of the troglobitic spider Tisentnops mineiro (Araneae: Caponiidae)

ABSTRACT

Subterranean environments are often considered buffered from external environmental variation due to their stable temperature and humidity regimes. Nevertheless, caves remain closely connected to surface conditions, and both cave attributes and the surrounding landscape can influence the distribution and ecological responses of subterranean species. This study aimed to evaluate the influence of epigean (surface) and hypogean (subterranean) variables on the distribution of the troglobitic spider Tisentnops mineiro, and to characterise its spontaneous behaviours based on a preliminary laboratory trial of four subadult specimens sourced from a single cave. We hypothesised that the distribution of T. mineiro is dictated by the interplay of subterranean buffering and surface climate regimes. Specifically, we expected a positive relationship with cave area due to climate stability, but a negative relationship with high incident solar radiation and low dryseason precipitation. Distribution data were obtained from 491 caves in the Quadrilátero Ferrífero (Iron Quadrangle) speleological unit, Minas Gerais, Brazil across 13 physical and epigean climatic predictor variables. The key predictors of T. mineiro occurrence were cave area, minimum precipitation in the surrounding external environment and total incident solar radiation in the region. Seventeen distinct behavioural acts were documented, the most frequent being immobility, followed by selfcleaning and environmental exploration. Activity increased with greater thermal amplitude, showing a marked escalation when temperature fluctuations exceeded 2.4°C. These findings indicate that the distribution and behavioural dynamics of T. mineiro are shaped by the interplay between cave attributes and surface environmental conditions, highlighting the importance of landscape context for understanding and conserving subterranean species.

Pereira, T. S., de Oliveira, M. P. A., Prado, G. C., & Lopes Ferreira, R. (2026). Surface climate and cave morphology predict the distribution and behavior of the troglobitic spider Tisentnops mineiro (Araneae: Caponiidae). Journal of Natural History, 60(37–40), 1943–1955. https://doi.org/10.1080/00222933.2026.2713630