BRUSH SETAE ON THE ANTENNULES OF MALE EUCYCLOPINAE (COPEPODA, CYCLOPOIDA, CYCLOPIDAE)

The morphology and distribution of setal elements on the proximal segments of the antennules are studied in selected male eucyclopine and cyclopine copepods. Males of Homocyclops ater possess modified setal elements, referred to here as brush setae, which are homologues of normal, unmodified setae in females. Brush setae are absent in cyclopine males. It is inferred that brush setae are derived from bimodal setae (with combined mechanosensory and chemosensory capability). They differ from aesthetascs, which are never ornamented with setules in crustaceans. They also lack characteristics of typical aesthetascs, which are pure chemosensors. We recommend the term brush setae for these elements.