Genital feelers: the putative role of parameres and aedeagal sensilla in Coleoptera Phytophaga (Insecta).

The male copulatory organ (aedeagus) of the Curculionoidea and the Chrysomeloidea is originally composed of a median lobe and a tegmen with basal struts and distal parameres. Within the Phytophaga (=Pseudotetramera), the parameres have been reduced several times. Comparison of different types of parameres, median lobes, aedeagi lacking parameres, and investigation of dissected pairs in copula revealed that (1) parameres do not provide mechanical coupling, (2) mechanical footing is provided by the endophallus, (3) median lobes of Phytophaga bear different kinds of sensilla. Mechanical and behavioural interaction between male and female copulatory organs were studied morphologically and by observation of live, copulating pairs. For the first time, copulation of a Sagrinae-species (Chrysomelidae: Sagrinae: Mecynodera coxalgica) was investigated in detail.