Male and female crab spiders “cooperate” to mimic a flower

Abstract

Female crab spiders (Thomisus spp) are able to camouflage themselves as flowers not only to successfully avoid being preyed upon by birds but also to ambush flower-visiting insect prey (Nature 2002; doi.org/10.1038/415133a). This mimicry manipulates flower signals and may vary from species to species. However, do male crab spiders, which are usually much smaller in size and darker in coloration than females, also camouflage themselves in this way?

In a tropical rainforest in Xishuangbanna (Yunnan, China), we observed one male and one female crab spider (Thomisus guangxicus; Thomisidae) in an apparent partnership, to jointly mimic a single Hoya pandurata (Asclepiadaceae) flower. In this image, where the male crab spider lies on the back of the conspecific female, the male appears to mimic a flower's pistils and stamens while the female appears to mimic that same flower's fused corolla. The flower's complex color is matched as a whole only when individual spiders of both sexes are present. This could be an example of “cooperation” that expands the niche of both females and males in mimicry systems, and cooperating individuals may have improved survivorship and predation efficiency. It would also be interesting to investigate the co-evolution between male and female crab spiders.