Key and Lock

During mating, male odanate will use his anal appendages (key) to grasp the neck (lock) of female. The anal appendages of male is unique as different species will have different shape of anal appendages. On the other hand, the neck of female has unique structure as well which fixes into the shape of the anal appendages of male. Therefore, the grasp of male's anal appendage onto female's neck is very specific to species. The anal appendages and neck just act like key and lock. Showing below are how well the anal appendages fix into the neck of two damselfly species - Pseudagrion microcephalum and Prodasinuera collaris.


Pseudagrion microcephalum

Prodasineura collaris