The Reproductive Cycle of the Water Skink, Sphenomorphus quoyii

Abstract

Sphenomorphus quoyii is found near streams in a wide variety of climates; the animals of the present study were from the New England Plateau. In this area minimum winter air and soil temperatures frequently go below 0?C. There is a hibernation period from May to September (inclusive). Testis weights begin increasing in April and continue to do so throughout the hibernation period reaching a maximum by the September emergence. Ovary weights also begin increasing before the hibernation period and continue increasing until the ova are released into the oviduct in October. Seasonal variation is found in the number of relatively ripe ova, in ovum diameters and in oviduct diameters. Oviduct diameter varies with snout-vent length; there is no sharp distinction in size between oviducts which contained embryos the previous year and those which did not. From two to seven young are born in December or January. The sex ratio is skewed towards females except for a period of approximately one month after emergence from hibernation. * * * Sphenomorphus quoyii is distributed along the coastline of eastern and southeastern Aus- tralia and inland into the high altitude area of the Great Dividing Range. Lizards used in this study were all taken from Boorolong Creek, Dumaresq Creek or their smaller tributary creeks near Armi- dale, New South Wales (an area of 9 x 6 miles). This area, part of the New England Plateau, has an altitude of approximately 3,000 to 3,500 feet. Maximum and minimum environmental tempera- tures for 1967 and 1968, recorded at the University of New England, 14 miles from the study area, showed great seasonal fluctuation, minimum air temperatures frequently going below -5?C, the lowest reading being -7.6?C. Minimum soil temperatures at depths of 5 and 10 cm were as low as -0.7 and 1.1?C respectively. Summers were relatively hot with air and soil temperatures at 5 and 10 cm depth reaching maxima of 32.2, 40.2 and 36.2?C respectively. S. quoyii avoids very cold conditions by hibernating during the winter months of May to September (Veron, in prep.).