Functional protandry and seasonal reproductive cycle inSolatopupa similis(Bruguière) (Pulmonata Chondrinidae)

The study of the gamete maturation and the seasonal reproductive cycle of Solatopupa has been carried out by the histological analysis of both the ovotestes and the genital ducts of specimens which were periodically sampled from a natural, outcrossing population. S. similis has been demonstrated to be a true hermaphrodite, since both types of its gametes begin to differentiate together and probably undergo simultaneously the meiotic prophase; however, it could be considered functionally protandrous because male gametes come to maturity in spring and summer, while egg maturation and growth is delayed until the late winter. Mature sperms are stored throughout the year in a portion of the ovotestis duct (or first hermaphrodite duct) which functions as a seminal vesicle: thus, functional protandry is certainly not important as a self‐sterility mechanism. The behavioural and adaptive significance of this pattern of gametic maturation and auto‐sperm storage are also discussed.