Prevalence and mean intensity of infestation by Carcinonemertes carcinophila imminuta (Nemertea: Carcinonemertidae) in the gills of Callinectes danae and Callinectes ornatus (Decapoda: Portunidae) from São Sebastião, Brazil

Abstract

The nemerteans of the genus Carcinonemertes live in association with decapod crustaceans. Juveniles of Carcinonemertes carcinophila imminuta Humes, 1942 are found in the gills of their hosts. A total of 281 specimens (52 males and 229 females) of Callinectes danae Smith, 1869 and 373 (332 males and 41 females) of Callinectes ornatus Ordway, 1863 were inspected for the occurrence of Carcinonemertes carcinophila imminuta in their gills. The prevalence and mean intensity of infestation by these nemerteans with regard to sex, maturity, condition of adult female crabs (ovigerous or non ovigerous), size (carapace width) and molt stage of hosts were evaluated. A prevalence of infestation by Carcinonemertes carcinophila imminutaof 39.1% was found in the population of Callinectes danae; the mean intensity of infestation was 12.0±2.7, while intensity ranged from 1 to 268. In this host species, significant differences in prevalence were observed between males and females, juveniles and adults and ovigerous and non-ovigerous adult females. Prevalence of infestation did not differ significantly among crabs in different molt stages. Mean intensity did not differ significantly between males and females nor among crabs in different molt stages. Significant differences in mean intensity were observed between ovigerous and non-ovigerous adult females of Callinectes danae. A positive correlation was observed between prevalence of infestation and the carapace width of Callinectes danae females. The prevalence of infestation in Callinectes ornatus was 8.0%; the mean intensity of infestation was 2.7±0.4 while intensity ranged from 1 to 9. Prevalence and mean intensity of infestation did not differ significantly between males and females and juveniles and adults. Prevalence did not differ significantly among crabs in different molt stages. No correlation was observed between the prevalence of infestation and the carapace width of males and females of Callinectes ornatus.