Growth of individuals within the parasite-host association Bopyrina abbreviata (Isopoda, Bopyridae) and Hippolyte zostericola (Decapoda, Caridea), and variations in parasite morphology

Growth is an important ecological factor of species on which information is scant for host-parasite associations. A sample of 680 Hippolyte zostericola parasitized by the isopod Bopyrina abbreviata were collected at Términos Lagoon, Mexico, to evaluate the growth of both members of this association by the von Bertalanffy method, as well as longevity of parasitized and unparasitized hosts, and parasite females. Misidentification of bopyrid species could be attributed to morphological variations of stages of development, so the relative growth of some body parts of B. abbreviata females were estimated at different stages of development. Overall, H. zostericola parasitized by B. abbreviata had lower growth rate and longevity than did unparasitized shrimp. Unparasitized H. zostericola females lived longer (10.2 months) than males (8.9 months), but parasitized males lived longer (7.31 months) than females (5.62 months). B. abbreviata longevity (5.98 months) was similar to that estimated for its host (6.31 months). The relative growth of the morphological characters differed between immature and mature stages of B. abbreviata females; the appearance of coxal plates, tergal projections and the fusion of pleomeres was progressive throughout development, so a combination of characters is proposed to allow differentiation between immature and mature females of B. abbreviata.