LARVAE OF THE EASTERN PACIFIC SNAPPER HOPLOPAGRUS GUNTHERI (TELEOSTEI: LUTJANIDAE)

摘要

Pelagic larvae of Hoplopagrus guntheri (Lutjanidae) are described on the basis of a flexion larva (3.85 mm) and six settlement-stage postflexion larvae (18.05 to 20.14 mm) collected in the Gulf of California and at the Islas Tres Marias, near Mazatlan, Mexico. The Tres Marias specimens were previously treated by Fowler (1944) as a new genus and species of Serranidae (Deuteracanthus lonchophorus), and by Heemstra (1974) as Lutjanus jordani. Identifications of the postflexion larvae were established from fin-ray counts (D X, 14, A Ⅲ, 9) and the unique condition of the nares corresponding to that of juvenile and adult H. guntheri (i.e., the posterior nares are elongate grooves occluded by a membrane except for a narrow slit). Identification of the flexion larva is tentative, but counts of its fin rays and supports (corresponding to D X, 14, A Ⅲ, 9), together with morphological comparisons to larvae of some other eastern Pacific lutjanids, eliminated all species but H. guntheri and L. jordani. Positively identified L. jordani larvae were not available, but one tentatively identified specimen from off Costa Rica lacked several distinctive features shared by the flexion larva and postflexion H. guntheri. This, along with L. jordani's restricted Central American distribution, far to the south of the flexion larva's collection site in the central Gulf of California, supports identification of the flexion larva as H. guntheri. Characteristics of H. guntheri larvae shared with other described lutjanid larvae include a moderately deep and compressed body with 24 myomeres; a large head; a preanal length of 50.4-61.7% BL; very elongate dorsal-fin spine 2, pelvic-fin spine, and pelvic-fin ray 1; and moderate development of spination on several bones of the head and pectoral girdle. Distinctive features of H. guntheri are the extremely long, pigmented dorsal-fin spine 2 (51.1-57.9% BL) and pelvic-fin ray 1 (57.0-60.6% BL) present in both young and old larvae; smooth fin-spine margins; pronounced internal structure in the fin spines of the settlement-stage larvae; and a large bilobed patch of pigment laterally on the caudal peduncle of the settlement-stage larvae.