title: Ultrastructural study on the body surface of the acanthocephalan parasite Dentitruncus truttae in brown trout.
abstract: Scanning electron microscope (SEM) investigations on the holdfast elements, proboscis hooks, and trunk spines of Dentitruncus truttae (Acanthocephala, Palaeacanthocephala), an endoparasite of Salmo trutta (brown trout), provide more data about the surface of these taxonomic relevant structures. In both acanthocephalan sexes, the fully everted cylindrical proboscis possessed 18 longitudinal rows of hooks with 18 hooks per row (rarely 19-20). Hook length varied according to position on the proboscis; apical hooks were 40-52 microm long, middle hooks were 31.7-36.6 microm, and basal hooks were 38.1-40 microm. Starting from the anterior end of the metasoma, numerous cuticular spines (26.7-30 microm in length) were visible and their number progressively decreased posteriorly. SEM observations of D. truttae hooks and spines revealed the presence of many surface striations on each proboscis hook. These surface striations were absent from trunk spines. From the base of the hook, the striations ran parallel toward the point of convergence. Additionally, survey of longitudinal and transversal sections of the hook using transmission electron microscope confirmed that the hook surface was not smooth. SEM comparison with the hooks of several palaeacanthocephalan species, as well as with the hooks of species belonging to Eoacanthocephala and Polyacanthocephala, indicated that the striations are currently exclusive to D. truttae proboscis hooks.
authors.affiliation: Department of Biology and Evolution, University of Ferrara, 44100 Ferrara, Italy. dzb@unife.it
authors.forename: Bahram S
authors.initials: BS
authors.lastname: Dezfuli
authors.forename: Alice
authors.initials: A
authors.lastname: Lui
authors.forename: Luisa
authors.initials: L
authors.lastname: Giari
authors.forename: Paola
authors.initials: P
authors.lastname: Boldrini
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Giovinazzo
mesh_terms: D000049:Acanthocephala / Q000033:anatomy & histology* / Q000648:ultrastructure*; D000818:Animals; D005260:Female; D005393:Fish Diseases / Q000469:parasitology*; D006374:Helminthiasis, Animal / Q000469:parasitology*; D006790:Host-Parasite Interactions; D008297:Male; D008855:Microscopy, Electron, Scanning; D014337:Trout / Q000469:parasitology*