Studies on the Scincid Lizard Leiolopisma zelandica (Gray, 1843) with Notes on Leiolopisma aeneum (Girard, 1857)

Abstract

In a study area of a quarter acre, a population density of 222 lizards was determined by marking and recapture over a two year period. The species Leiolopisma zelandica is described, and variation of head plates, body scales and proportions shown to occur. The testes are at minimal mass in June-July, enlarging during summer. Copulation was observed once. Ovulation occurs in October, gestation is twelve weeks, parturition is in January. Three to five young are born per female. Earlier ovulation and two young per female are shown by Leiolopisma aeneum. The young increase two and a half times in weight before hibernating when growth ceases. In the next growing season the young reach small adult size at 16 months and become sexually mature at 20 to 21 months. Growth continues throughout life becoming progressively slower. Young in their first year form the only distinct age-size class. Most lizards showed regenerated tails which are rarely as long as the original and have different scalation. Foods in order of preference are spiders, hemipterans, coleopterans, isopods and amphipods. One-third of the lizards examined were infected rectally with a nematode Pharyngodon sp. L. zelandica has a definite home range of about 15 square yards, overlapping with that of others. Aggressive territorial behaviour was not observed. The juveniles form the disperse phase of the population. In Wellington only partial hibernation occurs; the period is four and two-thirds months. Moulting was observed in October-November and is completed within 24 hours, the scales being shed in patches. The life history of L. zelandica may not be typical of other members of the genus in New Zealand. The portable resistance thermometer bridge and thermistor head described allowed continuous body temperature records to be made in the field and laboratory. The temperature of L. zelandica responds rapidly to external radiant heating, rising above the air or substratum temperatures. Body temperature lies close to substratum temperature under most conditions but may approximate air temperature at low temperatures. The critical maximum for the species is about 38°C. and minimum activity occurs at 5°C. The temperature of maximum voluntary tolerance is 34.6°C., the preferred body temperature 29.0°C. ± 1.0°C.