Sexual cycles of New Zealand lizards, with particular reference to the gecko Hoplodactylus maculatus (Boulenger)

Abstract

The male and female sexual cycles of the gecko Hoplodactylus maculatus are described using monthly samples collected from Turakirae Head, Wellington, during 1967-68 and 1983-84. These are compared to the cycles at other locations in New Zealand. The sexual cycles of various other New Zealand lizards are also considered. The testes, epididymides, vasa deferentia and kidneys of males were histologically examined, as were the oviducts of females obtained live. The diameter of the largest ovarian follicles of all females and the length and width of the uterine eggs of pregnant specimens were recorded. The corpora lutea of pregnant and non-pregnant females were measured. In H. maculatus at Turakirae Head during 1983-84, ovulation and parturition occurred about September/October and March respectively. Sperm were present in the oviducts from April to September. The epididymis and sexual segment were hypertrophied from February to June. Sperm were present in the epididymis and vas deferens from December to September/October. Spermatocytogenesis was continuous, but most evident in June and July. Spermiogenesis was most active from November to April/May, but occurred at a slow rate during June and July. Sperm were present in the seminiferous tubules, epididymis and vas deferens in all months during 1967-68. The female sexual cycles during 1967-68 and 1983-84 were very similar. Copulation probably occurs two months earlier in Otago than at Turakirae Head. Spermiogenesis ceases two or three months earlier at Otago (perhaps an artefact due to methodology), and ovulation and parturition occur slightly earlier. In the skink Leiolopisma nigriplantare maccanni in Wellington, spermiogenesis begins about November and ceases during April. Spermatocytogenesis occurs during the latter month. Spermiogenesis finishes approximately one month earlier in Otago. Mating probably occurs at the same time in both locations. No differences were found between the sexual cycles of the three species proposed by Patterson (1985). Two types of reproductive cycle are hypothesised to occur in the New Zealand geckos and skinks. In Hoplodactylus spp. (except H. duvauceli) mating, vitellogenesis and spermatocytogenesis occur in summer/autumn/early winter, whereas in Naultinus spp. and Heteropholis spp. they occur in spring. Ovulation and spermiogenesis probably occur earlier in the year in Hoplodactylus spp. relative to the other two genera. The genus Leiolopisma contains both types of cycle. In New Zealand lizards the time of mating appears to be correlated with the spermatogenic cycle (i.e., spermiogenesis begins later in those species which mate in spring compared to those which mate in summer/autumn). The present distribution and behaviour of New Zealand lizards cannot explain the types of sexual cycle they possess. Ad hoc hypotheses concerning historical distributions and climatic events are also unsatisfactory.