Mimicry complex in two central European zodariid spiders (Araneae: Zodariidae): how Zodarion deceives ants

Abstract

Ant-eating spiders, Zodarion germanicum and Z. rubidum, were found to resemble ants structurally (size, colour, setosity) and behaviourally (ant-like movement, antennal illusion). Zodarion germanicum mimics large dark ants, such as Formica cinerea, whereas Z. rubidum resembles red ants, e.g. Myrmica sabuleti. Thus, these spiders are generalized Batesian mimics. The two spiders use aggressive mimicry during prey capture. When a spider carries a captured ant it will try to pass by approaching ants using special deceiving behaviour, which is based on imitation of ants' nestmate recognition. The spider first taps the antennae of the curious ant with its front legs (transmitting a tactile cue), then exposes its prey (the ant corpse) which the ant antennates (thus the corpse transmits an olfactory cue). The distal part of the front legs of Zodarion are almost without macrosetae similar to the antennae of ants. Additionally, all the other legs are covered with flattened incised setae, which imitate the dense setosity of ants' limbs. These remarkable microstructural imitations are believed to improve imitation of tactile signals by spiders. Moreover, by tapping, zodariids can presumably recognize the approaching intruder and decide whether to undertake the risk of deception or to run away.