Segregation of three corynosoma spp. (acanthocephala) in paratenic hosts?

Corynosoma acanthocephalans in their paratenic fish hosts in the northern Baltic Sea

En 1996-1997, nous avons etudie les stages cystacanthes de trois especes de Corynosoma (Acanthocephala), C. strumosum et C. semerme, ainsi qu'une nouvelle espece C. magdaleni parasite du chabot a quatre cornes (Myoxocephalus quadricornis) dans le golfe de Bothnie. Les longueurs du tronc et du proboscis permettent de differencier les trois especes de parasites. La stabilite temporelle de l'infection par Corynosoma est etudiee en comparant nos resultats a ceux obtenus dans la meme zone geographique centrale et cotiere) en 1977-1982 (Valtonen, 1983a). Comme C. magdaleni et C. strumosum n'etaient pas differenciees a cette epoque, elles ont ete groupees sous l'appellation "C. strumosum" pour les…

The impact of sexual selection on Corynosoma magdaleni (Acanthocephala) infrapopulations in Saimaa ringed seals (Phoca hispida saimensis)

In free-living animals sexual selection is a central force shaping the spatial distribution of individuals in a population as well as sexual size dimorphism. We studied the influence of sexual selection on spatial distribution, female-to-male body size ratio, and female mating success of acanthocephalans in a natural host population of Saimaa ringed seal (Phoca hispida saimensis) harbouring a single intestinal helminth species, Corynosoma magdaleni. The acanthocephalans were always found along the full length of the small intestine; however, the site selection varied among the individual seals according to the age of the infection. The distribution of male acanthocephalans was not random wi…