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 (...

Social and colonial spiders as model systems for host-symbiont interactions at different levels of organization

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Social and colonial spiders as model systems for host-symbiont interactions at different levels of organization

Symbiotic interactions, which run the gamut from microbial assemblages to synergistic or antagonistic interactions with macro-organisms, can shape ecological communities across levels of biological organization, from solitary hosts to large social groups. Web-building spiders have given rise to two types of social systems: outbred colonial orb weavers, which form web complexes with a modular structure and no cooperation, and inbred social species with tightly knit societies displaying cooperation within shared communal webs. We synthesize recent findings on the macro- or micro-organisms that colonize individual spiders or their living quarters in social and colonial species, highlighting their potential contributions to population stability and vulnerability as a function of the hosts’ social and breeding system. The tightly knit societies of social spiders facilitate microbial homogenization and prolonged associations with potential macro-symbionts, whereas colonial spiders likely maintain more transient relationships with heterospecific inquilines. Individual spiders and colonies must navigate relationships with diverse inquilines, ranging from mutualistic fungi that attract prey to their webs to behavior-manipulating parasitoid wasps. Macro-symbionts exploit colony resources, including nest materials for living quarters, spider-caught prey for food, or feed on spiders or their eggs. Micro-symbionts seem to colonize all tissues or materials, except eggs, with some having greater affinity for specific host substrates. These systems offer insights into broader ecological and evolutionary questions, including the role of symbiosis for host population stability, adaptation, and ecosystem function. Understanding how host-symbiont dynamics scale from individuals to communities provides critical perspectives on the mechanisms that structure cooperative and antagonistic interactions in nature.

Cassidy, S. T., & Avilés, L. (2026). Social and colonial spiders as model systems for host-symbiont interactions at different levels of organization. Current Opinion in Insect Science, 101521. https://doi.org/10.1016/j.cois.2026.101521