Redescription of the first zoeas of six Macrobrachium species (Decapoda: Caridea: Palaemonidae) occurring in Japan

The first zoeas of six Japanese Macrobrachium species, M. equidens (Dana, 1852), M. formosense (Bate, 1868), M. grandimanus (Randall, 1840), M. japonicum (De Haan, 1849), M. lar (Fabricius, 1798) and M. nipponense (De Haan, 1849), are redescribed from specimens hatched in the laboratory. The first zoeas described here differ considerably from previous published descriptions in appendage morphology and chromatophore pattern. The present examination demonstrates that, except for M. shokitai Fujino & Baba, 1973, first zoeal morphology among the seven Japanese species can be distinguished by using the combined characteristics of chromatophore pattern and the armatures of the mandibles, maxillule, and third abdominal segment.