The genus Sibogasyrinx has to date included only four species of rare deep-water Conoidea, each known from few specimens. In shell characters it strongly resembles three distantly-related genera, two of which, Comitas and Leucosyrinx, belong to a different family, the Pseudomelatomidae. A molecular phylogenetic analysis of a large amount of material of Conoidea has revealed the existence of much additional undescribed diversity within Sibogasyrinx from the central Indo-Pacific and temperate Northern Pacific. Based on partial sequences of the mitochondrial cox1 gene and morphological characters of 54 specimens, 10 species hypotheses are proposed, of which six are described as new species: S. subula sp. nov., S. lolae sp. nov., S. maximei sp. nov., S. clausura sp. nov., S. pagodiformis sp. nov. and S. elbakyanae Kantor, Puillandre & Bouchet sp. nov. One of the previously described species was absent in our material. Most of the new species are very similar and are compared to Leucosyrinx spp. Species of Sibogasyrinx are unique among Conoidea on account of the high intrageneric variability in radular morphology. Three distinct radula types are found within Sibogasyrinx, two of which are confined to highly supported subclades.