Two species of limid clams, Acesta sphoni and Acesta mori, were observed and sampled from seven localities in the Gulf of California, Mexico. The two species are known to occur on seamounts and escarpments along the north-eastern Pacific margin of the United States. This report provides the first records of each species in the Gulf of California and the greatest depth records for both species. Though they occasionally overlap geographically, the two species are clearly stratified by depth, with A. sphoni occupying shallower and warmer, hypoxic waters, and A. mori occupying deeper and colder, oxic waters. The species are easily distinguished morphologically. The shells of A. mori have very fine radial ribbing for a smooth appearance and are more rounded and inflated, whereas those of A. sphoni are narrower and more elongate with 31 to 77 strong radial ribs. The largest individuals sampled were A. sphoni. For each species, DNA analyses revealed arrays of mitochondrial haplotypes similar to those found previously at north-eastern Pacific localities along the California, Oregon and Washington margins, providing no evidence for geographical subdivision throughout this newly extended range.