Observations on the development of the external genitalia in some Indian penaeid prawns

In penaeid prawns as in some other crustaceans the external sexual organs, the petasma or andricum in the male and the thelycum in the female have attained great prominence as they offer reliable characters of taxonomic differentiation of species and have attracted the attention of very early taxonomists like Bate (1888) and Kishinouye (1896, 1898 & 1900). Later Heldt (1938), Burkenroad (1939) and Kubo (1949) carried out intensive studies on the structural modifications of these organs in many species of penaeids. The latter author made extensive investigations on the morphological changes in the external genitalia of both sexes during growth and development. Eldred (1958) observed the development of the genitalia and impregnation in the pink shrimp, Penaeus duorariim. The development of the petasma and thelycum of the Indian prawn, Metapenaeus dobsoni was described by Menon (1951) during the course of his study of the early life history of the species