Abstract
Early and middle larval development of P. penicillatus reared in the laboratory for 160 days was examined. Although no puerulus was obtained, the larval development during the experiment was morphologically divided into seven stages. Average molting intervals were around six days for instars I-III and ten days after instar V. In most cases, one pair of setae was regularly added on the exopod of the 3rd maxilliped after instar II and those on the exopod of the 1st and the 2nd pereopods after instar V. Growth in body length and other body parts was indicated as an exponential curve. The growth patterns of the antennular and the antennal length and the abdominal width were changed at stage V. Morphological variations in larval development among individuals in the same instar were observed after instar IV. Early-stage phyllosomas of P. penicillatus were distinguished from other phyllosomas of the present genus in having two spinules on the proximal segment of the maxilla, in stead of three spinules in others.
