Calotheca is a widespread sub-Saharan flea beetle genus comprising 36 species already described. In this contribution, we describe a new species, Calotheca leonardii sp. nov., from the Republic of South Africa. It shows the most remarkable similarities with Calotheca thunbergi. In fact, based on external morphology, specimens of the new species were previously considered within the variability of Calotheca thunbergi. We highlight the main diagnostic characters of the two species and provide photographs of the habitus, median lobe of the aedeagus, and spermatheca. We also report information on their geographical distribution and host plants.