Spawn in two deep-sea volute gastropods (Neogastropoda: Volutidae) from southwestern Atlantic waters

Abstract

The gastropods Odontocymbiola pescalia and Provocator corderoi and their egg capsules were collected by the R/VPuerto Deseado from the Mar del Plata Submarine Canyon (~37º53´ S, at depths of 291-1404 m) and from BurdwoodBank (~54º27´ S, 128-785 m). Odontocymbiola pescalia egg capsules measured 15.67 ± 3.38 mm in diameter. Theywere subspherical in shape with an external calcareous layer. Each egg capsule contained 3-5 embryos and whitematerial as extra embryonic food. Embryos grew to a size of up to 9.3 ± 1.1 mm in mean shell length before hatchingas crawling juveniles. The spawn of P. corderoi consisted of a single dome shaped egg capsule of 14.17 ± 1.5 mm indiameter, attached to hard substrata by a basal membrane with a rounded outline. A curved semilunar furrow (seam)on one side of the capsules was always present. The number of embryos per capsule was 2-6. Embryos hatched ascrawling juveniles with a shell length of 5.9 ± 0.6 mm. The size and number of whorls in the hatchling shell suggesteda slow rate of development, akin to many other deep-sea invertebrates. The egg capsules and reproductivedevelopment strategies of both species were compared with those from other congeneric representatives