Two new species-groups of Lycocerus Gorham are defined, L. kuatunensis group and L. continuatus group, which could be differentiated from all others except L. canthariformis (Ishida, 1986) by the aedeagus with conjoint dorsal plates of parameres. The L. kuatunensis group is composed of five species, including L. kuatunensis (Wittmer, 1995), L. svihlai (Wittmer, 1995) comb. nov., L. nigroapicis Y. Yang et X. Yang, 2013, L. bifurcatus Y. Yang et X. Yang, 2013, and L. nigrigenus Y. Yang et X. Yang, 2013, and the L. continuatus group consists of two species, L. continuatus sp. nov. and L. parameratus Y. Yang et X. Yang, 2013. These two groups differ from each other in the aedeagus possessing longitudinal ridges on inner surface of conjoint dorsal plates of parameres or not, laterophyses compressed or slender, accessory gland uniformly thin or slightly enlarged apically. A morphological phylogenetic analysis shows that the two new groups are closer to the L. canthariformis subgroup of the L. vitellinus group due to the similarity in their aedeagi. The above species are provided with habitus photos, aedeagi, reproductive systems and abdominal sternites VIII of female. A key to the species and a distribution map are provided.