GONADAL CYCLES OF THE WESTERN AUSTRALIAN LONG-NECKED TURTLES CHELODINA OBLONGA AND CHELODINA STEINDACHNERI (CHELONIA CHELIDAE)

WA Museum Records and Supplements | Updated 1 decade ago

Abstract: Seasonal changes of testis volume, spermatogenesis, follicular development, and oviducal eggs for preserved specimens of Chelodina oblonga and Chelodina steindachneri are reported. Testis cycles of both species show a typical temperate zone chelonian pattern. The germinal epithelium is quiescent, during winter, spermatogonia start to multiply in spring, followed by spermatocytogenesis in late spring and summer. Spermiogenesis peaks in January and February in C. steindachneri and in April in C. oblonga. Spermiation starts during summer and continues until winter.

In C. oblonga, follicular enlargement starts during summer and continues until spring. Oviducal eggs were found in October and November, and up to three clutches may be laid between September and January. Females have a reproductive potential of 25-40 eggs per year.

Follicles of C. steindachneri start to enlarge in late spring. During summer and autumn, there is a stable phase without enlargement. Vitellogenesis is completed before ovulation in spring. Only one clutch of seven to eight eggs is laid per season. This pattern seems to be an adaptation to a relatively long period of aestivation.