ANNUAL GONADAL CYCLE OF THE LAND SNAIL SCUTALUS-TUPACII (PULMONATA, BULIMULIDAE)

The annual gonadal cycle and its relation to the seasons were investig ated in the land snail Scutalus tupacii (d'Orbigny). Collections of ad ult snails were carried out monthly over two consecutive years. The an imals were processed for anatomical and histological studies. The ovot estis is composed of a number of tubules or elongated acini, each one containing both male and female sexual cells as well as Sertoli and fo llicular cells. Spermatogenesis and oogenesis occur in all the acini. The annual cycle of the ovotestis was divided into three phases: 1) Pr e-breeding (September-November: Spring), characterized by the reactiva tion of spermiogenesis and the subsequent increase in number of mature sperm; 2) Breeding (November-February: Spring-Summer), characterized by the great number of spermatozoa in the gonad, and the highest propo rtions of mature oocytes; 3) Post Breeding (March -September: Autumn-W inter, with abundance of spermatogonia. oogonia and primary spermatocy tes, and the interruption of spermiogenesis. Although the proliferatio n of male and female germinal cells is practically coincident, male ga metes attained maturity at least one month before the female gametes. The post-breeding period occurs during hibernation which is coincident with the dry season. Based on the data obtained, the annual cycle of reproductive activity in this species depends principally upon the wet or rainy season.