Discovery of postcopulatory mate guarding in Copepoda Harpacticoida (Crustacea)

Mating behaviour of four species of Tisbe (Tisbidae) and of Paramphiascella fulvofasciata (Diosaccidae) was filmed with a videocamera during 1992 and 1993 at the University of Oldenburg. This behaviour is complex and can be divided into different phases: grasping of the female; courtship; copula and postcopulatory mate guarding. During courtship both partners lie parallel in opposite directions with their ventral sides facing each other. The male strokes the abdomen of the female with his second to fourth peracopods. As a result the female becomes motionless. The copula is a quick process of only a few seconds during which spermatophore transfer takes place. When this has happened, males do not leave the females but become inactive and are carried around by them for varying lengths of time. This pattern and the fact that only adult partners are involved in these associations prove that this behaviour is very different from the precopulatory mate guarding presumed to be ubiquitous among Harpacticoida. Cases of postcopulatory mate guarding have never been explicitly demonstrated for Harpacticoida. The minimum duration of guarding was found to match the time necessary for spermatophore discharge. Guarding is, therefore, interpreted as a strategy to secure paternity. New definitions are given for courtship, copula and postcopulatory mate guarding in Harpacticoida to help avoiding misinterpretations of associations between adult partners. Such misinterpretations abound in the literature.