Reproductive biology of the nudibranch Doris fontainei d'Orbigny, 1835 (Gastropoda: Opisthobranchia) from the Magellanic Region

The present study describes the egg deposition, embryonic and larval development, and reproductive behavioral traits of the South American dorid nudibranch Doris fontainei d'Orbigny, 1835, observed in laboratory under controlled conditions. Behavior during copulation and spawning was recorded using a digital video camera. Copulation and spawning lasted 2-4 h and 22-23 h, respectively. The spawned mass reached 1.80 m in length and was coiled in a counter-clockwise direction from the centre with one edge affixed to the substrate. The ribbon contained numerous small capsules, each having 2-4 eggs of about 86 mu m in diameter. Intracapsular egg development lasted about 14 days at 14.5 degree C, culminating with the release of up to 1.25 million veliger larvae per egg mass. The new veliger larvae showed incipient development of the foot and a relatively small protoconch (ca. 158 mu m), indicating they enter a planktotrophic phase. A comparison with other nudibranchs, and particularly with dorids, suggests that D. fontainei has an annual cycle whose egg mass fits a morphological pattern typical of the family. The characteristics of its encapsulated development show it is one of the most fecund species among those having this pattern, which also explains, in part, its geographical dispersion from Peru in the Pacific to northern Argentina in the Atlantic.