Ant-eating twigs and stalks: The natural prey of Tmarus and Monaeses (Araneae: Thomisidae) in the Western Palaearctic, analysed by using online-accessible wildlife photography

Abstract

The diet of the Western Palaearctic species of the closely related crab spider genera Tmarus Simon, 1875 and Monaeses Thorell, 1869 is only little known. A quantitative analysis of images showing spiders with prey, collected from the World Wide Web and the literature, suggests that both genera mainly prey on ants (Hymenoptera: Formicidae), while occasionally capturing other arthropods, such as spiders (Araneae). Most images depict feeding spiders that hold ants anterior-dorsally at the articulation of head and pronotum. Tmarus galapagosensisBaert, 2013, from the Galapagos Islands, is known to attack ants by a bite to this region, which, in combination with the photographic evidence, supports the hypothesis that Western Palaearctic representatives of both genera attack ants in a similar way. Three species of Tmarus and two of Monaeses were identified from the images feeding on ants, demonstrating that probably all species of both genera at least include ants in their diet. In conclusion, Western Palaearctic Tmarus and Monaeses are myrmecophagous predators and probably have a narrow trophic niche in nature. Furthermore, both genera represent interesting model organisms for the study of trophic specialisation in widespread taxonomic clades.