AbstractThe karyotype and the NOR localization of five taxa of Heteronemiidae, belonging to the three genera known from Somalia are reported. The cytotaxonomy of stick insects in general and, in particular, of Heteronemiidae is rather poorly developed. The present paper aims to contribute to filling this gap. Diploid chromosome numbers are: Ramulus sansibarus, 44; R. lingulatus, R. affinis and Burria longixipha, 42; Palophus rothschildi, 32; the X chromosomes are the largest of the complement, and all taxa have an XX‐XO sex determination mechanism. In spite of the numerical similarity of the ramuline set, karyotypes differ markedly for chromosome constitution, their haploid N.F. ranging from 20 to 30, and for satellite/Ag‐NOR localizations. If R. libanicus (2n = 30, XX‐XY) is also considered, it can be seen that karyotype differences of taxa presently ascribed to the genus Ramulus are of the same magnitude as those of heterogenerically related species. The karyological features, together with morphological and ootaxonomical data, clearly suggest a genus splitting into at least three species‐groups: the sansibarus‐, the affinis‐ and the libanicus‐like artenkreis.