After our taxonomic revision of Ootheca Chevrolat, 1837, and the description of Oothecoides Kortenhaus & Wagner, 2011 and Ootibia Kortenhaus & Wagner, 2012, it became clear that a further four galerucine species, closely related to the above named taxa, form a distinct monophyletic group, that constitutes a new genus, Oosagitta gen. nov. with O. anningae sp. nov., O. geescheae sp. nov., O. melanopicta sp. nov. and O. thomasi sp. nov.. Exosoma angolensis Laboissière, 1939, the type species of the new genus, and Ergana minuta Laboissière, 1937 are newly transferred to Oosagitta gen. nov. All species of Oosagitta gen. nov. are characterized by a broad body and pronotum, a more or less convex dorsum and short legs, and as such are most similar to the other above named genera. The antennae of Oosagitta gen. nov. are distinctly longer than those of Ootheca, Oothecoides and Ootibia. Genital structures of the males allow a reliable identification of the genus. (Re-)descriptions are given for all species, including semi-schematic illustrations depicting the habitus outline, shape of the basal antennomeres and the median lobe. Photographs of the name-bearing types and distribution maps are provided.