Morphological features of the larvae of spider crab Pugettia quadridens (Decapoda: Majidae) from the Northwestern Sea of Japan

The entire cycle of larval development of the spider crab Pugettia quadridens (de Haan, 1850) (Decapoda: Majidae), widespread in Peter the Great Bay (Sea of Japan) is studied under the laboratory conditions. The development cycle of this species comprises prezoea, zoea I, zoea II, and megalopa. At a temperature of 18–20°C larval development took from 11 to 15 days. Zoea II is described in detail for the first time. Many morphological characters are found distinguishing zoea and megalopa of P. quadridens in Russian waters from the larvae of this species in Japanese and Korean waters. Some characters of larvae are similar in P. quadridens and the related species of the genus Pugettia. The larvae of P. quadridens occur in the plankton of Vostok Bay from late June to late October with a density up to 5 ind/m3 at a surface water temperature of 13–21°C. They are easily distinguished from the other brachyuran larvae of this region by the absence of lateral spines on the carapace.