A new species of the mygalomorph spider genus Euagrus Ausserer (Araneae: Euagridae) from central Mexico and new records of E. gus Coyle from Tlaxcala

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  A new species of the mygalomorph spider genus Euagrus Ausserer (Araneae: Euagridae) from central Mexico and new records of E. gus Coyle from Tlaxcala Abstract  A new species of the spider genus Euagrus Ausserer, 1875 from temperate pine-oak forests in the states of Tlaxcala and Hidalgo, Mexico is described: E. pulque sp. nov. The description of the new species is based on male and female adult specimens. Additionally, Euagrus gus Coyle, 1988 is recorded for the very first time in the state of Tlaxcala. These species have sympatric distributions in La Malinche National Park, Tlaxcala. With this description, the diversity of the genus increases to 23 species, with Mexico harboring the highest diversity with 17 described species.  Valdez-Mondragón, A., Salinas-Velasco, H. V. & Bueno-Villegas, J. (2026). A new species of the mygalomorph spider genus Euagrus Ausserer (Araneae: Euagridae) from central Mexico and new records of E. gus Coyle from Tlaxcala. Zootaxa 5810 (...

Which web to invade? Argyrodine kleptoparasites differentiate among architecturally different host webs

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Which web to invade? Argyrodine kleptoparasites 1differentiateamong architecturally different host webs

Abstract

Kleptoparasitism, the theft of resources from another organism, is a survival strategy found across the animal kingdom. Many argyrodinae cobweb spiders (Theridiidae) are obligatory kleptoparasites that have largely abandoned web building, relying instead on webs of larger hosts. Theory predicts, and limited prior research indicates, that kleptoparasites are not randomly distributed among host webs, and prior studies indicate that web architecture (size and tenure) and prey availability impact kleptoparasite abundance and host choice. We investigate the distribution of multiple argyrodine kleptoparasite species among three contrasting host types in Madagascar's Analamazaotra National Park: Nephilingis (Nephilidae, large nocturnal orb weavers), Caripetella (Pisauridae, large nocturnal sheet web builders), and Anelosimus (Theridiidae, small cathemeral social spiders constructing three-dimensional tangle webs). Although small in scope, this study is the first to take a real-time snapshot of multi-species endemic communities of spider kleptoparasites and their in-situ distribution across contrasting host webs. We found an unexpectedly high diversity of ten kleptoparasite species that, remarkably, are not conspecific with the five that were previously known from all of Madagascar. Kleptoparasite species composition and abundance varied across the three hosts: some appeared host-specific while others seemed versatile. In general, argyrodine kleptoparasites evidently discriminate among hosts but choose among them with varying degrees of astucity. At the community level, very limited data exist, and based on our study we can only speculate that species assembly into host webs involves a complex interplay between host preference and species competitive hierarchy. Future field research should investigate this system as a community of multiple interacting species to gain a more comprehensive understanding of the rules that may govern the assembly of diverse kleptoparasites into equally variable host webs. Synergistically, laboratory experiments are needed to elucidate key cues facilitating kleptoparasite web detection and choice; likely involving eavesdropping on pheromones intended for the hosts male.


Agnarsson, I., Ramahefarisonc, F.-N., Matthíasdóttir, H. H., Kudari, L., Dagsson, M. M., Baldursdóttir, N. G., Bergsdóttir, R. S., Halldórsdóttir, R. B., Magnússon, S. B., Björnsdóttir, S. H., & Gregorič, M. (2025, March 10). Which web to invade? Argyrodine kleptoparasites differentiate among architecturally different host webs. EcoEvoRxiv . https://ecoevorxiv.org/repository/view/8729/