Larval development ofEuphausia similis (Crustacea,Euphausiacea) in Sagami Bay,central Japan

The larvae ofEuphausia similis G. O. Sars in Sagami Bay, Central Japan, are described. Nauplius, metanauplius, calyptopis and furcilia stages are included. In the furcilia stage, six forms are identified on the basis of the form of the pleopods and the number of terminal telson spines. Furcilia I: a pair of non-setose pleopods and seven terminal telson spines. Furcilia II: a pair of setose and three pairs of non-setose pleopods and seven terminal spines. Furcilia III: four pairs of setose and a pair of non-setose pleopods and seven terminal spines. Furcilia IV: five pairs of setose pleopods and five terminal telson spines. Furcilia V: five pairs of setose pleopods and three terminal telson spines. Furcilia VI: five pairs of setose pleopods and one terminal telson spine. On the basis of the developmental pathway of the larvae,E. similis is suggested to be related toE. spinifera, E. longirostris, E. hanseni and theE. gibboides group species. The size ofE. similis larvae, expressed as total length, in Sagami Bay varied according to month. The sizes of calyptopis III and furcilia I–V stages were smallest in November and March and largest in May.