Reproductive Ecology ofQuasipaa verrucospinosa(Bourret, 1937): Living in the Tropical Rain Forests of Central Vietnam

Abstract

Quasipaa verrucospinosa, the Granular Spiny Frog, is a discoglossid frog endemic to Vietnam and known only from its original description. We report the discovery of three populations of this species and describe the reproductive, fat body, and liver mass cycles for males and females. Results showed that males reached sexual maturity at 98.36 mm snout–vent length (SVL) and an age of nine months. Females reached sexual maturity at 109.45 mm SVL and an age of 11 months. Testes of males began to increase in volume in late June, and maximal testicular activity occurred from September to December. Testis size began to decrease in January and was smallest in April. Histological analyses revealed that sperm were not present throughout the year, indicating discontinuous reproductive activity for adult males. Reproductive females were observed only during the main rainy season months, indicating that females reproduce seasonally. The gonads of females began to increase in volume in July and maximal egg production occurred during the main rainy season (September to December). Females started to lay their eggs in July, and there were significant differences among mean clutch size and numbers of oviductal eggs or yolked follicles, vitellogenic follicles, and nonvitellogenic follicles. Clutch size was correlated significantly with female SVL and varied between seasons and months. The results of multiple regression analyses indicated that precipitation, but not temperature, was associated positively with testicular and ovarian volume.