Joining the dark side: waterfall spiders in subterranean habitats, with the description of a new genus and two new species from Brazil (Araneae: Trechaleidae)

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  Joining the dark side: waterfall spiders in subterranean habitats, with the description of a new genus and two new species from Brazil (Araneae: Trechaleidae) Abstract Trechaleidae is a family of spiders often recognized by its semiaquatic species, but its diversity extends beyond these well-known examples. In this study, we describe Troglotrechalea gen. nov. , a new genus with two novel species, T. faleroae spec. nov. and T. agorai spec. nov. , found exclusively in subterranean habitats within karst formations in central and southeastern Brazil. Both species exhibit pale coloration, but unmodified eyes and legs if compared to other species in the family. The slight degree of troglomorphism, along with their geographic and habitat records, suggests that these species are restricted to hypogean habitats, although they probably move through epigean habitats. Additionally, we report in detail the occurrence of the trechaleid genera Enna O. Pickard-Cambridge, 1897, Heidrunea Brescovi...

Behavioral manipulation in a cobweb spider: insights from comparisons between parasitized and healthy spiders

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Behavioral manipulation in a cobweb spider: insights from comparisons between parasitized and healthy spiders

Abstract

Some Darwin wasps of the Polysphincta genus group (Ichneumonidae, Pimplinae) are ectoparasitoids that induce behavioral alterations in their host spiders, resulting in the construction of modified webs, structures known as "cocoon webs”. One relevant aspect for comprehending the manipulation mechanism employed by these wasps involves comparing the structures of webs built by individuals during manipulation with webs constructed during other periods of the spiders' lives. In this study, we present a novel instance of behavioral modification in Cryptachaea jequirituba (Araneae: Theridiidae) parasitized by Zatypota alborhombarta and assess whether cocoon webs are associated with webs constructed during molting, growing, and maternal care. We observed that cocoon webs constructed by spiders parasitized by last-stage larvae showed a reduction in vertical and gumfoot lines. Additionally, there was an increase in forked distal ends of lines and the presence of silk threads around the web shelter. These web traits likely contribute to enhancing web resistance and stability. In addition, we observed that cocoon webs are similar to webs constructed by spiders during molting and show some similarities with webs built during maternal care. These results suggest that the manipulation mechanisms induced by wasps in this cobweb spider may be based on the activation of innate processes.

Cifuentes-Vargas, E.T., de Pádua, D.G., Santos, A.J. et al. Behavioral manipulation in a cobweb spider: insights from comparisons between parasitized and healthy spiders. J Ethol (2025). https://doi.org/10.1007/s10164-025-00848-6