A new sap beetle species, Lobiopa penrosei Cline & Kinnee sp. nov., is described from Baja California Sur, Mexico. Habitus and genitalia images are provided. Major characters distinguishing L. penrosei include: dorsal surface setation consisting of all light colored thin and spatulate/subclavate setae with no dark to piceous setae present; spatulate/subclavate setae straight/erect not curved; and internal sac sclerites of male genitalia with a paired basal field of spines as well as ejaculatory rods with constricted bases. A review of Lobiopa Erichson is given, including biological notes on some of the inclusive members as well as a checklist of all described species.