Spawning and reproductive cycle of Odontocymbiola magellanica (Gmelin, 1791) (Mollusca: Gastropoda) in Golfo Nuevo Patagonia, Argentina.

G. BIGATTI & PABLO E. PENCHASZADEH

Rio de Janeiro, Brasil

Congreso; XVIII Encontro Brasileiro de Malacología,; 2003

Universidade Federal do Rio de Janeiro

ABSTRACT   The volutid snail Odontocymbiola magellanica from Patagonia has a high economic potential as a natural resource. This “zigzag” snail lays single egg capsules, which are attached to hard substrates such as other mollusks´ shells, stones or elasmobranch eggs; and it shows a peculiar white calcareous external cover, which differentiates it from all the other studied volutes. External calcium layer of the egg capsule is presumably secreted by a calcareous gland in the snail’s foot .The egg capsule is spheroidal, with a mean diameter of 35 mm. The uncleaved egg diameter vary between 280 and 300 microns; 6 to 10 embryos develop in each egg capsule. Hatching occurs at the crawling stage, reaching the embryo its total metamorphosis growing up to a shell length of 8 to 11 mm inside the eggcapsule due to the presence of nutritive substances in the intracapsular liquid. Samples taken by scuba diving in shallow waters show a spawning season from July to November. Egg capsules in different stages of embryos development were found in the field from July to January. Histological slides show the same reproductive pattern as infer by the existence of females spawning in the field.