Predation on amphibians by spiders (Arachnida, Araneae) in the Neotropical region

Abstract

Herein, we report observations about spider predation on anurans (adults and juveniles) in Central Amazonia and a literature review of spiders preying on amphibians in the Neotropical zoogeographic realm. We conducted field observations in Reserva Florestal Adolpho Ducke, Manaus, AM, and observed eight predation events on Bufonidae, Dendrobatidae, Hylidae, and Leptodactylidae frogs. The predators belong to the spider families Ctenidae, Pisauridae and Theraphosidae. Besides the families of spiders found in this study, two others - Lycosidae and Sparissidae - were found in literature. Frogs from families Centrolenidae and Microhylidae, and a caecilian (Gymnophiona, Caeciliidae) were found in literature also. There is a significant correlation between the length of the anuran (snout-vent length) and the length of spiders (cephalotorax and abdomen length). The size of the spider is similar or slightly lesser than the anuran prey. In general, the spiders preyed on adult and juvenile frogs in the breeding season. Spiders are opportunistic predators and prey on small frogs. Theraphosidae prey upon sub adults of large anurans and caecilians. As spiders can reach high densities on the forest floor - especially species of the genera Ctenus and Ancylometes - this interaction may be ecologically important for breeding anurans. Our reports and literature data provide evidence that spiders commonly prey on amphibians in Neotropic, but the impact of predation on populations of amphibians is unknown.