DESCRIPTION OF THE NAUPLIAR STAGES OF MEGABALANUS-TINTINNABULUM (CIRRIPEDIA, BALANIDAE)

Larval development of Megabalanus tintinnabulum was studied in the lab oratory. At 26 +/- 1 degrees C the development from nauplius I-VI requ ired about 4 days, when the diatom Chaetoceros wighami was used as foo d. Detailed morphological drawings and setation formulae of appendages of all 6 naupliar stages are presented for the first time. Notable fe atures of the nauplii include the presence of a spinulated lateral mar gin, a trilobed labrum with teeth, long dorsal and posterior shield sp ines, a single tooth on the inner prong of the antennal gnathobase, co mb-shaped cuspidate setae on the antennae, and spines and simple denti culate setae on the mandibular endopodite in naupliar stage II. The pr esent description of the nauplii is not in full agreement with the pre vious description of this species from this coast by Daniel (1958). Di fferences in stage sizes, naupliar morphology, and setation of appenda ges are used to distinguish this species from other megabalanines and the nauplii of megabalanines from those of balanines in the Balanus am phitrite group.