The first genus with four sac-like structures in the vulva in the cobweb spider subfamily Theridiinae Sundevall, 1833 (Araneae: Theridiidae)

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  The first genus with four sac-like structures in the vulva in the cobweb spider subfamily Theridiinae Sundevall, 1833 (Araneae: Theridiidae) Abstract The morphological characters of copulatory organs are the most important basis in spiders for identification. In theridiids, a vulva with four sac-like structures is mostly associated with the subfamily Hadrotarsinae but has never been recorded in Theridiinae. Based on specimens collected from subtropical forest canopies in China, a new Theridiinae genus that has four sac-like structures in the vulva is described: Sactheridion gen. nov., with the type species S. chuan gen. & sp. nov. from Sichuan Province, China. Photos, diagnosis, description, and a distribution map of the new genus and new species are provided. Hu, C., Yao, Z., Liu, J. & Xu, X. (2026) The first genus with four sac-like structures in the vulva in the cobweb spider subfamily Theridiinae Sundevall, 1833 (Araneae: Theridiidae). Zootaxa, 5884 (1), 167–175. http...

Hyaluronidase activity of Indian ornamental tarantula (Poecilotheria regalis) venom is significantly reduced by commercial Latrodectus mactans and American scorpion antivenoms

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Hyaluronidase activity of Indian ornamental tarantula (Poecilotheria regalis) venom is significantly reduced by commercial Latrodectus mactans and American scorpion antivenoms

Abstract

A recent clinical case involving a Poecilotheria regalis bite was treated with Mexican L. mactans antivenom (Aracmyn Plus, Silanes, Mexico), resulting in the improvement of some of the symptoms. This could be attributed to cross-reactivity caused by structural similarities between certain components of L. mactans and P. regalis venoms. The aim of the present study was to evaluate the cross-reactivity of P. regalis venom with commercial antivenoms that target the venom of the Latrodectus mactans spider and American scorpions. Hyaluronidase activity was evaluated via a turbidimetric method, while edema was evaluated in rat paw via a histopathological analysis. Cross-reactivity was determined using SDS-PAGE and western blotting. The results obtained showed that both antivenoms significantly reduced the hyaluronidase activity of P. regalis venom and that induced by other tarantula venoms. Aracmyn Plus did not reduce inflammation caused by P. regalis venom. Furthermore, it was previously observed that this antivenom failed to reduce the characteristic muscle cramps induced by this venom. Finally, western blotting revealed that both antivenoms showed cross-reactivity with P. regalis venom. The above findings suggest that hyaluronidases and other high-molecular-weight components exhibit structural similarities across the venoms from different arachnid species.
García-García, M., Mosqueda, J., Escobar-Cabrera, J. E., Murillo-Maldonado, J. M., & José Alejandro, G. (2025). Hyaluronidase activity of Indian ornamental tarantula (Poecilotheria regalis) venom is significantly reduced by commercial Latrodectus mactans and American scorpion antivenoms. Toxicon, 108543. https://doi.org/10.1016/j.toxicon.2025.108543