Making a doughnut-shaped egg mass:: Oviposition behaviour of Vibrissaphora boringiae (Anura: Megophryidae)

Vibrissasphora boringiae produces doughnut-shaped egg masses (i.e., circular mass with central depression) that are attached to the underside of submerged rocks in running water. The oviposition behaviour of this species was observed for the first time, and explains how egg masses were shaped. The male used the right hindlimb to push the eggs up to the bottom surface of the rock, while the pair rotated horizontally and counter clockwise. Three limbs of the female provided the support and power for the rotation. The male was positioned on the dorsal-left side of the female, and formed a rare asymmetric inguinal amplexus. This type of oviposition behaviour may be common in megophryid frogs that produce doughnut-shaped and circular egg masses.