The rare Horn of Africa buthid genera Lanzatus Kovařík, 2001, Orthochirus Karsch, 1891, and Somalicharmus Kovařík, 1998 were newly collected. Lanzatus is reported for the first time from Somaliland, and Orthochirus for the first time from Ethiopia. We describe two new species, Lanzatus somalilandus sp. n. from Somaliland, and Orthochirus afar sp. n. from Ethiopia, both discovered during scorpiological expeditions in 2011–2016. Information is provided for all Horn of Africa species belonging to these three genera: their taxonomy, distribution, and ecology, fully complemented with color photos of live and preserved specimens, as well as their habitat. The morphology of the enigmatic scorpion Somalicharmus whitmanae Kovařík, 1998 is illustrated in detail. The first author recently collected 52 specimens including the first known females, which reveal natural colors, and show sexual dimorphism in the shape of the pedipalp chela and metasoma which are broader in males, and in the shape of the basal middle lamella of the pectines, which in females is extremely dilated and rounded. We describe the hemispermatophore, which is furnished with an atypically elongated basal lobe, and the chelicera, which differs from that of all other known extant buthids. Other characters indicate possible affinity with the south African buthid Karasbergia methueni Hewitt, 1913. We also describe karyotypes of S. whitmanae. We identified 2n=20 in seven males from two localities and 2n=21 in one male. In both analyzed localities we found males with reciprocal translocations that form conspicuous multivalents. The male with 2n=21 includes fission of one chromosome that increases the diploid number and implicates an odd number of chromosomes.