Larval development of the Pacific sandperch (Prolatilus jugularis) (Pisces: Pinguipedidae) from the Independencia Bight, Pisco, Peru

Abstract

Morphological development of larvalProlatilus jugularisfrom Bahia Independencia, Pisco, Peru is described. Two hundred and thirty-two specimens were collected with plankton nets in 2000; a developmental series of 40 individuals (2.5–25.9 mm: recently hatched through transformation) was assembled using morphological features and pigmentation.Prolatilus jugularishatches at approximately 2.5 mm, notochord flexion begins at ∼5.7 mm and ends at ∼6.9 mm, and transformation begins at an unknown size between 14.2–20.3 mm (probably near 20 mm). Diagnostic features of the larvae include a robust body with large head bearing small preopercular spines that begin to form by late preflexion stage; preanal length just under half of body length early in the preflexion stage increasing to near two-thirds of body length in the postflexion stage; and pigmentation primarily on the snout, opercular region, dorsally on the head and gut, laterally above the hindgut, and on the ventral margin of the tail through early flexion stage. A broad mid-lateral stripe begins to form on the trunk and tail late in the flexion stage and dorsal pigmentation forms on the trunk and tail in the postflexion stage. Pectoral-fin rays are first to begin forming, in mid-preflexion stage, followed by principal caudal-fin rays, then by pelvic-, dorsal- and anal-fin rays which apparently begin to form simultaneously near the end of preflexion stage. The dorsal fin is long and continuous, with III–IV short spines and 27–29 soft rays, the anal fin contains 21–23 rays, the first one or two of which may be spine-like, the pelvic fins, with I spine, 5 rays, are below or slightly in front of the pectorals (18–20 rays), and there are 9+8 principal caudal-fin rays and 36–37 myomeres.