Behavioral evidence for two-stage sleep in spiders

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  Behavioral evidence for two-stage sleep in spiders Abstract Sleep is a fundamental behavioral state found across the animal kingdom, yet most of what we know about sleep is heavily vertebrate-biased. Studies are scarce or nonexistent in all but a few invertebrate lineages. A recent study of an REM sleep-like behavior in a jumping spider has reported unexpected parallels to sleep expression in vertebrates. So far, experimental evidence that these behavioral indicators truly represent sleep was lacking in spiders. Here, we present a comprehensive investigation into sleep behavior in the spider Portia fimbriata (Salticidae). We demonstrate diurnal activity, a free-running circadian rhythm, robust sleep architecture, regularly occurring REM-like behaviors, elevated arousal thresholds during those REM-like states, as well as rebound effects following sleep disruption. We conclude that the behavior we observe in spiders is behavioral sleep, providing evidence for an REM-like sleep sub...

A new species of Harpactocrates Simon, 1914 (Araneae: Dysderidae) from Cantabria, Spain

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A new species of Harpactocrates Simon, 1914 (Araneae: Dysderidae) from Cantabria, Spain

Abstract 

A new species of Harpactocrates Simon, 1914 is described from Cantabria, northern Spain as Harpactocrates trenti sp. n. The species is closely related to H. ravastellus Simon, 1914, but can readily be distinguished by the more globular tegulum and a longer, hook-shaped embolus. Female specimens also show a characteristic configuration of the valve folds, visible through the cuticle as two anteriorly diverging lines. Detailed morphological descriptions, images of genital structures, and distribution data are provided. The discovery of H. trenti sp. n. increases the known Iberian representatives of the genus to nine species and highlights the need for further sampling in poorly surveyed regions, where additional undescribed taxa may occur.

Narro-Martín, A. J. (2026). A new species of Harpactocrates Simon, 1914 (Araneae: Dysderidae) from Cantabria, Spain. Arachnology 20(5): 693-698.