ABSTRACT Information concerning Neastacilla californica is currently scarce. In fact, its distribution range is not yet well defined; this species is currently reported from Point Conception to Point Loma along the California coast, USA, and also in the Gulf of California, Mexico. In this note, we present a new zoogeographical record of N. californica with information derived from a sample of taken in July 2012 during a monitoring expedition in the area inside of the Guerrero Negro Lagoon, at Peninsula de Baja California, Mexico, at 4.3 latitudinal degrees from the southernmost point reported on the Pacific coast. Additionally, we present a comparative summary of the main diagnostic features of this species and a series of photographs that allow observing characteristics of N. californica, contributing to the knowledge of the species.