title: First report of gastrocotylinean post-oncomiracidia (Platyhelminthes: Monogenoidea: Heteronchoinea) on gills of flyingfish (Exocoetidae), snapper (Lutjanidae), dolphinfish (Coryphaenidae), and amberjack (Carangidae) from the Gulf of Mexico: decoy hosts and the dilution effect.
abstract: Larvae, identified as post-oncomiracidia of the suborder Gastrocotylinea (Monogenoidea), were collected from formalin-fixed gills excised from six species of marine fishes captured from the Gulf of Mexico off Mississippi and Florida: common dolphinfish, Coryphaena hippurus and pompano dolphinfish, Coryphaena equiselis (both Perciformes, Coryphaenidae); gray snapper, Lutjanus griseus (Perciformes, Lutjanidae); greater amberjack, Seriola dumerili (Perciformes, Carangidae); and Atlantic flyingfish, Cheilopogon melanurus and sailfin flyingfish, Parexocoetus hillianus (both Beloniformes and Exocoetidae). Based on a combination of diagnostic morphological features, the specimens were divided into two basic forms, each of which was further subdivided into two morphotypes. No gastrocotylinean post-oncomiracidium had been reported previously from these hosts. Of the six host species, only C. hippurus serves as a host (unconfirmed) for the adult of a gastrocotylinean species, suggesting that the recorded fishes from the Gulf of Mexico comprise dead-end hosts acting as decoys for the oncomiracidia. These comparatively non-susceptible "decoy hosts" apparently dilute the susceptible fish-host population and by intercepting infective larvae (oncomiracidia) decrease the abundance of parasites on their typical hosts.
authors.affiliation: Department of Health and Nutrition Sciences, Idaho State University, Pocatello, Idaho 83209, USA. kritdela@isu.edu
authors.forename: Delane C
authors.initials: DC
authors.lastname: Kritsky
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Bullard
authors.forename: Micah D
authors.initials: MD
authors.lastname: Bakenhaster
mesh_terms: D000818:Animals; D023761:Beloniformes / Q000469:parasitology*; D005393:Fish Diseases / Q000469:parasitology*; D005880:Gills / Q000469:parasitology; D006790:Host-Parasite Interactions; D007814:Larva / Q000033:anatomy & histology / Q000145:classification / Q000502:physiology; D010473:Perciformes / Q000469:parasitology*; D010986:Platyhelminths / Q000033:anatomy & histology / Q000145:classification* / Q000502:physiology; D012623:Seawater / Q000469:parasitology; D014201:Trematode Infections / Q000469:parasitology / Q000662:veterinary*