EGG AND LARVAL DEVELOPMENT OF SPANISH SARDINE, SARDINELLA-AURITA (FAMILY CLUPEIDAE), WITH A SYNOPSIS OF CHARACTERS TO IDENTIFY CLUPEID LARVAE FROM THE NORTHERN GULF-OF-MEXICO

Larvae of the Spanish sardine are poorly known and the taxonomy of Sar dinella species are poorly understood. Despite high morphological vari ability in adults, recent evidence provides no clear indication of two sympatric species of Sardinella in the western Atlantic Ocean and all are considered S. aurita. Larval evidence supports the high morpholog ical variability reported for adult Spanish sardine, but does little t o augment the understanding of Sardinella taxonomy in the western Atla ntic. Eggs and larvae of S. aurita are described in this paper. Spawni ng apparently occurs at night. Eggs average 1.08 mm in diameter, have a single oil globule, and are smaller than those of most other clupeid s. Length-at-hatch is about 2.5 mm standard length and growth in the l aboratory averaged about 1.2 mm.day-1 at 26-27-degrees-C. Transformati on begins at 16 mm and is complete at 23 mm. During transformation, fu ll complements of fin rays develop, the gut shortens, and dorsal and a nal fins move forward. Larval development of Spanish sardine off Brazi l is delayed compared to that of northern Gulf of Mexico specimens. La rvae of S. aurita are recognized primarily by melanophores bilaterally situated on the nape. Pigment differences provide a more versatile ta xonomic character than myomere counts alone for identifying clupeid la rvae because myomere counts overlap among some species. Primary pigmen tation characteristics that separate larval clupeids, including S. aur ita, from the northern Gulf of Mexico are: 1) presence or absence of p igment at the notochord tip and on the nape; and, 2) the standard leng th at which pigment appears along the cleithrum both above and below t he pectoral fin, dorsally along the hindgut, and along the caudal pedu ncle.