Growth and development of Pleurogenoides orientalis (Srivastava, 1934) (Trematoda: Lecithodendriidae) in the intermediate and definitive hosts

Two phases with an intervening brief lag-phase are recognized during the growth of the metacercaria of Pleurogenoides orientalis in the intermediate host (nymphs of Tramea limbata ), the first phase being characterized by rapid growth and organogeny and the second phase by limited growth and development. The phases of growth and development of the metacercaria are correlated with various events in the cyst-forming process. The growth of the adult fluke in the definitive host (Rana cyanophlyctis ) is characterized by a short initial lag-phase followed by a rapid phase during which there is rapid growth. Comparison of allometric growth parameters of various organs of the metacercaria and of the adult revealed definite allometric shifts. The validity of various species included in the genus Pleurogenoides is examined in the light of observations made on intraspecific variation in P. orientalis .