A Review of California Margarinotus Marseul (Coleoptera: Histeridae: Histerinae: Histerini), with Descriptions of Two New Species Author Caterino, Michael S. Santa Barbara Museum of Natural History, 2559 Puesta del Sol Rd., Santa Barbara, CA 93105, U. S. A mcaterino@sbnature2.org text The Coleopterists Bulletin 2010 2010-03-01 64 1 1 12 journal article 10.1649/0010-065X-64.1.1 1938-4394 4892928 MARGARINOTUS MARSEUL, 1853 Diagnosis. Among Histerini , Margarinotus are generally recognizable by the presence of a complete outer subhumeral elytral stria. Most species have multidenticulate, rounded protibiae, with only poorly developed marginal teeth, with the protibia shallowly excavate between the teeth on the anterior surface. However, they are most unambiguously diagnosed by their distinctive aedeagus, with an elongate median lobe with articulated dorsal armature that rotates upwards when extruded ( Figs. 2 , 4 , 5 , 8 , 10 ). In California , they are the most common all-black Histerini , and the most common Histerini in general (though that is not to say that they are common – they are rarely encountered). Of the five species of true Hister known to occur in California , none have a complete outer subhumeral stria, and only Hister militaris Horn is fairly widespread, with Hister abbreviatus F. extending barely into the northern part of the state, and Hister comes Lewis and Hister coenosus Erichson extending into the more monsoonal-influenced extreme southeastern part of the state. Two species of Spilodiscus Lewis occurring in California exhibit red elytral maculations. The adventive Margarinotus obscurus (Kugelann) has not yet been recorded in California , but is known from Washington and Oregon , and may occur in northern California . This species has an abbreviated outer subhumeral elytral stria, and can only be assigned to the genus on the basis of genitalic and protibial characters.