Sphenophorus spangleri Anderson, new species, from Mazatlán, Sinaloa, Mexico is described. The species is very similar to Sphenophorus lineatus Champion and Sphenophorus quadrivittatus Gyllenhal, two similarly colored Mexican species that have a red pronotum with three longitudinal black stripes. The new species is distinguished by its larger body size, eyes narrowly separated in dorsal view, antennal club with the apical pilose portion very small, proportionally narrow body form, very long, slender, linear tarsal articles which are not expanded laterally, and the pygidium with deep, dense, subconfluent punctures limited to the apical portion. Illustrations comparing the three species and a key to the three species are provided. A lectotype is designated for Sphenophorus lineatus Champion.