Reproductive Cycles of the Grass Lizard, Takydromus hsuehshanensis, with Comments on Reproductive Patterns of Lizards from the Central High Elevation Area of Taiwan

Abstract

In this study, I describe seasonal variations in the male and female reproductive cycles of Takydromus hsuehshanensis, an oviparous grass lizard endemic to the high altitude areas of Taiwan. Mean snout-vent length (SVL) of adult males (n = 78) and females (n = 105) were 60.5 mm (range = 47-72 mm) and 61.2 mm (range = 54-72 mm), respectively. Females exhibited a spring vitellogenic period with parturition occurring in May to July. The onset of vitellogenesis showed a negative correlation with the mass of the female fat body. Females produced two to four eggs per clutch, and clutch size was positively correlated with SVL: only females with SVLs equal to or larger than 61 mm produced a clutch consisting of four eggs. Two clutches were recorded during a single year in some individuals. Males exhibited a continuous spermatogenic pattern, but testis mass, accessory sexual organ mass, and seminiferous tubule diameter showed cyclical changes with a peak before the dormant months from September to December. The tubules of the epididymides were full of sperm from December to the following March, indicating that sperm were stored in the epididymides until the occurrence of ovulation in the spring. Male fat bodies exhibited the lowest mass from March to June, coincident with the period of reproductive activity. Male seminiferous tubule diameter exhibited a positive correlation with liver, fat body, and testis masses. However, seminiferous tubule diameter, as well as testes mass, had a negative correlation with precipitation. Timing of reproduction in four other sympatric lizards and clutch size variation in other Takydromus species are compared with those in T. hsuehshanensis.