Ecological Role of the Clam Jukesena foveolata (Bivalve, Cyamiidae) Inferred by Digenean Parasites in Subantarctic Waters

Abstract

Bivalves serve as the first intermediate hosts in the life cycles of some digeneans,but little is known about their larval stages along the southwestern Atlantic coast. Theselarvae may provide valuable insights into the ecological role of mollusks in parasite lifecycles and marine food webs. This study offers a morphological, histological, and molec-ular (ITS2, 28S rDNA) description of the larval stages of three digenean species parasitiz-ing the bivalve Jukesena foveolata in the Beagle Channel, Tierra del Fuego Province, Argen-tina. Sporocysts containing cercariae of a monorchiid species were found infecting thegonads and digestive glands (p = 2%), while metacercariae were encysted in the foot (p =7%). Additionally, metacercariae of Renicola sp. (Renicolidae) were located between thetubules of the digestive gland (p = 2%), and metacercariae of Bartolius sp. (Gymnophalli-dae) were found in the extrapallial space (between the mantle and the valve, p = 13.5%),where they elicited a histopathological reaction with the secretion of a calcareous, igloo-shaped coating. The monorchiid larvae are described here for the first time in this bivalve,with fish as their definitive hosts. Metacercariae of Renicola sp. and Bartolius sp., both ofwhich use coastal birds as definitive hosts, have been previously recorded in other mol-lusks from the Argentine coast. This study contributes to our understanding of the lifecycles of digeneans from the southwestern Atlantic coast and the role of bivalve hosts inmarine food webs.