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 (...

Identification and Seasonal Abundance of Web- and Air-Borne Sex Pheromone Components of Western Black Widow Spiders, Latrodectus hesperus

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Identification and Seasonal Abundance of Web- and Air-Borne Sex Pheromone Components of Western Black Widow Spiders, Latrodectus hesperus

Abstract

Sex pheromones mediate mate location in many animal taxa. Widow spider males are attracted to sex pheromones disseminating from female webs. Upon arrival on a web, males court in response to web-borne contact pheromone components. N-3-Methylbutanoyl-O-methylpropanoyl-L-serine methyl ester (1) is the single known, weakly effective, contact pheromone component of female western black widows, Latrodectus hesperus. Moreover, the seasonal periodicity of pheromone signalling by female spiders is unknown. We tested the hypotheses that females of L. hesperus (1) deposit multiple contact pheromone components on their web that transition to mate-attractant pheromone components, and (2) increase pheromone signalling during the primary mating season. Analyses of web extract by gas and liquid chromatography-mass spectrometry (GC-MS; LC-MS) revealed N-3-methylbutanoyl-O-methylpropanoyl-L-serine (7), the corresponding acid of 1. Web extract of unmated female L. hesperus, and the synthetic blend of 1 and 7, were equally effective in eliciting courtship by males but web extract induced more sustained courtship. Tested singly, 7 prompted longer courtship behaviour by males than 1. Synthetic isobutyric acid (10), the hydrolysis product of 1 and 7, attracted male spiders in a field experiment. The abundance of 1 and 7 on female webs, with expected corresponding dissemination of 10 from webs, peaked during the summer when males are most abundant, indicating strategic sexual signalling by female spiders.

Fischer, A., Fischer, A.J., Gries, R. et al. Identification and Seasonal Abundance of Web- and Air-Borne Sex Pheromone Components of Western Black Widow Spiders, Latrodectus hesperus. J Chem Ecol 51, 36 (2025). https://doi.org/10.1007/s10886-025-01590-6