Spawn characteristics in Adelomelon ferussacii (Donovan, 1824) (Gastropoda: Volutidae) from southern Patagonia, Argentina

Abstract

South American volutids are very homogeneous with regard to their reproductive mode. These gastropods generally spawn egg capsules containing few eggs; the embryos feed on substances contained in the intracapsular fluid and hatch as crawling juveniles. Adelomelon ferussacii lives on subtidal mud or sandy bottoms, yet the egg capsules collected in San Julián, Santa Cruz, Argentina, were found on flat smooth subtidal rocks. The egg capsule is globose and hemispherical, flexible, opaque-white, and the attachment base is wide, measuring between 15-30 mm in diameter. One to six eggs were recorded inside each egg capsule. The embryonic development occurred in the interior of the capsule and eight stages are described. Crawling juveniles, with shells measuring between 11.25-14.8 mm, were observed at the last stage before hatching. Also a gregarious spawning event is recorded for the first time un the South American volutes.