False heads and sexual behaviour in a hairstreak butterfly, Callophrys xami (Lepidoptera: Lycaenidae)

Abstract

In several butterflies, the posterior end of the hindwings resembles a butterfly head when the butterfly is perched with its wings closed. There is evidence that this "false head" (FH) deflects predator attacks towards non-vital parts of the body. If the FH protects from visually oriented predators, its condition in an individual butterfly could provide information about its quality to prospective mates. We tested two hypotheses based on this idea by comparing the probability of mating, duration of copulation and size of the ejaculate received by females of Callophrys xami (Lycaenidae) with an intact FH and those with an ablated FH in a paired experiment. The absence of a FH had no effect on the probability of mating, but females with an ablated FH copulated for longer and received larger ejaculates, which supports the hypothesis that males prefer females with damaged FHs because this reveals the female's ability to deflect attacks. Male or female (or both) cryptic choice could also account for our results, but more studies are needed to test this.

Keywords

• lepidoptera
• lycaenidae
• theclinae
• callophrys
• deceptive morphology
• mating behaviour
• ejaculate
• mexico