The Biology of Fissurella Maxima Sowerby (Mollusca: Archaeogastropoda) in Northern Chile. 2. Notes on Its Reproduction

For 14 months, monthly samples were collected to study reproduction in Fissurella maxima at Huayquique. Results indicate that F. maxima is a dioecious species; no sign of hermaphroditism has been observed. The sex ratio is 1:1 in the different size classes analyzed. Ovaries are green and testis are median brown to yellowish white. Eggs in the ovary measure from 120-280 µ without envelopes. The gonads are parasitized by adult digenea trematods of the genus Proctoeces. Some effects of parasitism are discussed. Variations in mean monthly gonadosomatic index suggest that there is a main spawning period in late November-December (late spring-early summer) and a secondary period in July-August (winter). Fluctuations in mean gonad index show a close correlation with sea water temperature variations. The youngest mature specimens detected were about 5 cm in shell length (over two years old), but the majority of mature animals were over 6.5 cm.