Egg and larval development of laboratory-reared sergeant major, Abudefduf saxatilis (Pisces, Pomacentridae)
Abstract:Development of sergeant major, Abudefduf saxatilis, from late egg to early juvenile is described from captive-spawned and wild eggs and 71 laboratory-reared specimens. General morphological features include lateral compression, deep head, deep abdomen, and increasing preanal length through transformation. Notochord flexion had started in a 10-d old, 5.3 mm TL larva. Flexion was complete by 9.2 mm TL (17 d) and transformation at about 18.7 mm TL (28 d). Pelvic spines and rays developed during early preflexion (4.2 mm TL). The caudal fin began development at 4.4 mm TL. During preflexion (5.0 mm TL), dorsal rays and spine were present, and the anal fin began forming. Anal rays and spines were completed during flexion (9.2 mm TL). Newly hatched larvae had two distinct branched melanophores, one at the anterior part of the forehead, another behind the auditory vesicle. Preflexion larvae (up to 3.5 mm TL) also had melanophores along the ventral body midline between the anus and the notochord tip. Fairly heavy internal pigmentation occurred above the gut. The heavily pigmented pelvic fin was evident in 4.3 mm TL preflexion larvae. During late preflexion (3.5–5.5 mm TL) body proportions and pigmentation changed dramatically. Ventral pigment decreased, and the preanal body became deeper and heavily pigmented with scattered stellate melanophores. Flexion larvae had more pigmentation and were less transparent. The spinous dorsal fin became heavily pigmented during flexion. Throughout postflexion, postanal pigmentation increased, and during transformation, it spread toward the caudal fin. At 32 d, juveniles essentially had full adult coloration. Data from this study and for two species previously described facilitates larval identification for three of the 16 species in the western Atlantic. Pigmentation, pelvic fin size, and pectoral fin rays (17–18) probably are the most useful characters for identification of sergeant major larvae. They have larger, more heavily pigmented pelvic fins and a more heavily pigmented spinous dorsal fin than yellowtail damselfish (Microspathodon chrysurus) and beaugregory Stegastes leucastictus. Pectoral fins of the latter two species are larger and more pigmented.
Document Type: Research Article
Publication date: 1998-01-01
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