The reproductive cycles of the oviparous lizards

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Abstract
We examined the reproductive cycles of two species of the only oviparous genus Platysaurus in the predominantly viviparous family Cordylidae, endemic to Southern Africa. The reproductive cycles of Platysaurus capensis and P. minor were determined using data obtained from field caught and museum specimens. Males of both species exhibit testicular recrudescence during autumn (April-May) and maximum testicular volumes together with peak spermiogenic activity occur during winter through early summer (July-November). Small testicular volumes associated with testicular regression occur during mid-summer (December) through early autumn (March). Similarly, females of both species begin vitellogenesis in autumn, culminating in ovulation during spring (September-October). Females are ovigerous in summer (November through December). Clutch size is fixed on two eggs. In both species, male and female cycles are well synchronised. The fact that the autumn/winter ovarian cycles of these oviparous lizards correspond to that of viviparous members of the family Cordylidae adds to the data that suggest that the oviparous mode of reproduction in the genus Platysaurus represents one of the few known cases of an evolutionary reversal from the derived viviparous mode. Along with the viviparity-oviparity reversal a postnuptial-prenuptial testicular cycle reversal is suggested. Data presented in this paper support the hypothesis that the ancestral oviparous Platysaurus evolved on the Mozambique lowlands from a viviparous montane Pseudocordylus ancestor.

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