Age determination of wrinkled frog, Rana rugosa with special reference to high variation in postmetamorphic body size (Amphibia: Ranidae)

Abstract

Individual ages of postmetamorphic R. rugosa from three populations of Kyoto, Japan (Gondoike, Iwakura, and Kiyotaki), were determined skeletochronologically. From recaptured individuals, one LAG was confirmed to be formed per year. In all three populations, age at sexual maturity was 1-2 yrs in males and 2-3 yrs in females, though some females matured at the age of 1 yr. Longevity was at least 4 yrs in males and 5 yrs in females. Sexual size dimorphism was conspicuous in adults, and females were invariably larger than males. Females had a larger asymptotic size than males but growth rate differed between some localities only in males. In all populations, both sexes showed high variations in SVL and the variation was even higher in juveniles than in adults. This high variation is explained by a prolonged breeding season and resultant mixture of metamorphs with and without overwintering larval stage within a population of this species.