Notes on Indian wolf spiders: IV. Transfer of species previously included in the genera Crocodilosa Caporiacco, 1947 and Geolycosa Montgomery, 1904 (Araneae: Lycosidae)

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  Notes on Indian wolf spiders: IV. Transfer of species previously included in the genera Crocodilosa Caporiacco, 1947 and Geolycosa Montgomery, 1904 (Araneae: Lycosidae) The enigmatic Crocodilosa Caporiacco, 1947 sensu lato currently consists of five nominal species distributed in Africa and Asia (World Spider Catalog 2026). It was established for C. kittenbergeri Caporiacco, 1947, with a superficial generic diagnosis relying only on somatic features such as length of eye rows, leg spination and relative leg lengths (Caporiacco 1947). Roewer (1955), following Caporiacco’s (1947) generic diagnosis, drastically increased the number of Crocodilosa species by transferring several species from other lycosid genera, but most of these subsequently added species were later reassigned to their appropriate genera (World Spider Catalog 2026), highlighting the need for a re-examination of the type species and remaining congeners to clarify the validity of Crocodilosa. At present, the genus ha...

A state with increased arousal threshold in Araneus diadematus (Araneidae) measured in the wild: new evidence for sleep in spiders

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A state with increased arousal threshold in Araneus diadematus (Araneidae) measured in the wild: new evidence for sleep in spiders

Abstract

Sleep is a seemingly universal behavior across the animal kingdom, yet for the majority of species, experimental evidence thereof is still lacking. The recent report of REM sleep-like behavior in a jumping spider has highlighted the potential of spiders as a non-model organism to study invertebrate sleep. While behavioral evidence of potential sleep-states in spiders is strong, a crucial piece of evidence is so far lacking: a shift in arousability during sleep compared to awake states. Targeting a spider exquisitely suited for conducting experiments in the wild, we collected arousal threshold data for the diurnal orb-web spider Araneus diadematus. Our field experiments revealed significant differences in response latency between day- and night-times. Using a sound stimulus of 400 Hz with increasing amplitude that robustly triggers an anti-predatory response (raising of front legs), we tested both immobile and active spiders during the day and during the night. We found that spiders had a significantly longer response latency to the stimulus during nighttime immobility compared to immobile spiders during the day. There was no difference in the response latency between active spiders at night and active spiders during the day. Overall, our data demonstrate a shift in arousability during periods of night-time immobility in support of sleep in A. diadematus. Additionally, however, we found eight spiders that did not respond to the stimulus within the set time limit, most of which we encountered during daytime immobility hinting at additional sleep behavior during the day and a potential bimodal sleep pattern. Our study, along with recent work on jumping spider sleep-like behavior showcases the suitability of spiders for sleep research.

A state with increased arousal threshold in Araneus diadematus (Araneidae) measured in the wild: new evidence for sleep in spiders. Daniela Christina Rößler, Marie Elisabeth Herberstein 

bioRxiv 2023.10.19.563109; doi: https://doi.org/10.1101/2023.10.19.563109