A new species of Heptacarpus, a small shrimp marked with brown dots, is described. It ranges from Santa Rosa Island, California to Guadalupe Island, Mexico. Related to H. palpator and H. brevirostris, it can be distinguished from them by having only one large distal spine on the first segment of the antennular peduncle, and often having a spine at the distal end of the carpus of the first pereopod. Heptacarpus palpator is redescribed and better distinguished from H. brevirostris. Heptacarpus palpator ranges from Monterey Bay, California to the south, while H. brevirostris usually lives north of Monterey Bay.