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New non-sexual abnormalities in Acartia lilljeborgii (Copepoda, Calanoida)


During a study on diet of fishes from a tropical and high anthropogenically disturbed bay in Southeastern Brazil, a single stomach of Stellifer rastrifer (Perciformes: Sciaenidae) showed 13 individuals of Acartia lilljeborgi with similar anomalies, all related to the spines on the last somite. Different degrees of morphological alterations of the spine were observed, from spine-like setae at the base of the the main structure to both spines sharply bifurcated. A single bifurcated spine, left or right side, was the most frequent anomaly. As it is not a secondary character, anomalies were equally found for males and females, and in different developmental stages. This led us to believe that alterations did not occur during individuals' development, as usually reported for copepods anomalies and, therefore, the present findings had probably a congenital origin, affecting at least a subpopulation. This is the first report of such abnormalities features for the genus Acartia. (AU)