ONTOGENY OF THE PSEUDOHERMAPHRODITIC REPRODUCTIVE SYSTEM IN NASSARIUS VIBEX (GASTROPODA: BUCCINIDAE: NASSARIINAE)

Pseudohermaphroditism or imposex is an abnormality of thegastropodreproductive system caused by the effects of anenvironmentalpollutant, tributyltin, in which parts of the malereproductivetract develop in females. In this study, the post-larvaldevelopmentof the reproductive system in pseudohermaphroditic maleandfemale Nassarius vibex was investigated relative to normaldevelopmentto determine how and when the abnormalities associatedwithpseudohermaphroditism develop. Two populations of N. vibex werecompared:one exhibiting normal development, and one in which theanimalswere effected by pseudohermaphroditism. In the affectedN. vibexpopulation, a penis and anterior spermiduct developed veryearlyin ontogeny in both males and females. Normal reproductivesystemdevelopment was affected in some females, evidenced by fusionofthe induced spermiduct and anterior oviduct, or by abnormaloviductdevelopment. Several males displayed precocious maturationof thegonad in addition to early development of the anteriorspermiduct andpenis. (Received 25 April 2000; accepted 1 July 2000)