The rate of discovery of new species of Reduviidae (Insecta: Heteroptera) from 
North America has slowed in the 21st century. This is not surprising, given the 
conspicuousness and large distribution ranges of many Nearctic assassin bug 
species that are often collected using general insect collecting techniques. 
Nevertheless, biodiversity discovery in Nearctic Reduviidae is ongoing. We here 
describe a new species, Reduvius frommeri, n. sp., from Southern California that 
is so far only known from a small endemic range in the Sonoran Desert. With 
about 197 species, the genus Reduvius Fabricius is one of the most speciose 
genera of Reduviidae. The majority of species occur in arid- and semi-arid areas 
in the Afrotropical, Oriental, and Palearctic regions and only three species are 
New World endemics. A fourth species that occurs in the United States, Reduvius 
personatus Fabricius, is cosmopolitan and has been introduced to the Western 
Nearctic. The new species of Reduvius stands out amongst the four other Nearctic 
Reduvius species by the small size and pale body coloration with a contrasting 
dark head. Image plates documenting habitus and selected morphological details 
and maps are provided for the five species in the Nearctic. We conclude that 
efforts to document species diversity and distribution ranges even for 
conspicuous insects such as assassin bugs in fairly well studied biogeographic 
regions need to continue.