Nistos of two species of scyllarus

Abstract

For a number of years the authors have been studying the systematics and distribution of phyllosoma larvae of the Indian Ocean. During the course of these investigations a few nistos of Scyllarus were obtained. Scant attention seems to have been paid to the study of this important stage at which there is a change from the pelagic to the demersal phase in the life-history of scyllarids. Although the nistos show a resemblance to the adults, precise identification of these offers many difficulties. It is, however, hoped that by the gradual accumulation of data on the diagnostic characters of nistos belonging to the various species it would be possible ultimately to prepare a key for the identification of the nisto stage of scyllarids. Seven specimens, six of which belong to one species, collected from the Laccadives and one collected from the Gulf of Mannar off Mandapam form the subject matter of this paper. The specific identification in both these cases is provisional. The authors are grateful to Shri M. J. George for the help rendered in the determination of the species.