IntroductionScyllarid and palinurid lobsters are classified into three families (Palinuridae, Scyllaridae and Synaxidae) and share a long planktonic life period as phyllosoma larvae. Of these lobsters, the adult of Scyllarus and Panulirus species can be common and abundant in the coastal waters of Japan as well as in other temperate and tropical waters, including New Zealand and Australian waters. Most of the largesized Panulirus species are commercially important and are targets for fisheries, whereas small-sized Scyllarus species, despite having the largest species number among the scyllarid and palinurid lobsters, are of a low commercial value. In contrast to the Panulirus species, Scyllarus species are usually dominant among the phyllosoma larvae collected in coastal waters .There are many studies about larval recruitment processes of palinurid species, including larval distribution and larval transport/dispersal of Panulirus (Booth & Phillips 1994, Sekiguchi & Inoue 2002. However, few studies about scyllarid species exist (e.g. Inoue et al. 2000, Booth et al. 2005. According to the larval recruitment studies of Panulirus, phyllosoma larvae flush out from coastal waters into oceanic waters, and once again return to the coastal waters where they metamorphose into the puerulus stage to settle (Booth & Phillips 1994, Sekiguchi & Inoue 2002. Of course, for understanding the population dynamics of Scyllarus, we need to have enough information on the mechanisms of larval retention or larval transport/dispersal from coastal waters into oceanic waters and the reverse. Further, larval recruitment studies of Scyllarus contribute to additional resolution of unresolved recruitment processes in Panulirus. Accordingly, exact identification to the species level of field-caught phyllosoma larvae, particularly in the early stages, is essential for understanding larval recruitment processes of Scyllarus lobsters, as well as Panulirus ones.A total of 11 adult Scyllarus species have been reported to date in Japan and its neighbouring waters (Sekiguchi & Inoue 2002)
: S. aurora, S. bicuspidatus, S. batei, S. bertholdii, S. brevicornis, S. cultrifer, S. formosanus, S. kitanoviriosus, S. longidactilus, S. martensii, and S. rugosus.Scyllarus species, particularly three species (S. bicuspidatus, S. cultrifer and S. kitanoviriosus) are known to be abundant and dominant among the phyllosoma larvae collected in the same waters (Wada et al. 1985, Sekiguchi 1986a Abstract: For understanding larval recruitment processes of Scyllarus and Panulirus lobsters, exact species identification of field-caught phyllosoma larvae, particularly those of the early stages, is essential. Using ichthyoplankton samples from waters along the west coast of Kyushu to the Japan Sea coast of Honshu and the Kuroshio and KuroshioCounter Current regions, we described morphological features of the I to VIII (final) stage phyllosoma larvae of S. bicuspidatus and the IV to VIII stage larvae of S. cultrifer. The larvae of equivalent stages of two Scyllarus species are...