Hidden in the wrack: spider (Arachnida, Araneae) diversity and new records for Italy from Posidonia banquettes

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  Hidden in the wrack: spider (Arachnida, Araneae) diversity and new records for Italy from Posidonia banquettes ABSTRACT Posidonia oceanica (L.) Delile beach wrack deposits (banquettes) are a characteristic coastal habitat of the Mediterranean Sea, yet their invertebrate communities remain poorly studied. Here we report the results of a survey from January to November 2024 of the spider fauna (Order Araneae) associated with Posidonia banquettes at Sant’Agostino beach (Civitavecchia, Latium, central Italy), using four complementary sampling methods (surface and underground pitfall traps, Berlese-Tullgren funnel extraction, and visual census). A total of 161 specimens were collected, with 17 species assigned to 11 families among adult individuals. The dominant families were Argyronetidae (39.4%), represented exclusively by Chaerea maritimus Simon, 1885, and Gnaphosidae (33.8%). Three species are recorded for the first time in Italy: Dysdera gamarrae Ferrández 1984, Gnaphosa jucu...

Locomotor behaviour of tropical wolf spiders is affected by external temperature and body size, not load bearing

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Locomotor behaviour of tropical wolf spiders is affected by external temperature and body size, not load bearing

Ectothermic animals depend on ambient temperature to regulate internal temperature. This dependence affects many aspects of their behaviour, including locomotion, foraging and reproduction. Additionally, ectotherms are more vulnerable in environments with extreme hourly temperature fluctuations and their activity patterns likely match those of favourable temperatures. Here, we studied Pardosa wolf spiders (Lycosidae) in the highland tropical paramos of Costa Rica. We tested two hypotheses to elucidate the factors that influence variation in locomotor behaviour. First, we tested whether locomotor behaviour is driven by temperature variation. Female spiders experimentally exposed to higher temperatures (30 °C) moved approximately four times faster than those exposed to lower temperatures (7 °C). Second, we tested whether locomotor behaviour is modulated by the maternal care strategy of these spiders. Females carry an eggsac externally by holding it with the distal spinnerets. The eggsac can represent up to 36% of the spider's body size. However, females moved at the same speed regardless of whether they carried an eggsac or not. This demonstrates that the maternal care strategy does not affect their locomotor performance. In contrast, temperature plays a crucial role in driving locomotion. Our findings expand our understanding of how temperature fluctuations in extreme environments challenge ectotherms’ ability to move and, by extension, escape predators and locate mates and food.

Damián Villaseñor-Amador, Leonardo Vilas-Bôas M.P. de Cerqueira, Quimey Gómez, Francisca Zamora Cornejo, Julia Paulucci, Ignacio Escalante, Locomotor behaviour of tropical wolf spiders is affected by external temperature and body size, not load bearing, Animal Behaviour, 2023, ISSN 0003-3472, https://doi.org/10.1016/j.anbehav.2023.10.003.