¿De dónde son? Provenance of a South American species of seed beetle new to California

In 2012 an infestation of unfamiliar seed beetles was discovered in eastern California feeding within the seeds of Mexican palo verde (Parkinsonia aculeata). These turned out to be a species native to South America, Penthobruchus germaini (Coleoptera: Chrysomelidae: Bruchinae). How did they get to California? Where did they come from? Fortunately, in addition to these specimens from Blythe, we had previously collected this species in Argentina and Paraguay. While this species is also known from southern Brazil and Uruguay, we had enough geographic coverage to develop a molecular study intended to identify the most likely source location for this introduction. The introduced population shows no genetic variation, suggestive of a very limited founding population. There is also strong support for a provenance of northeastern Argentina. While Mexican palo verde has been spread throughout the tropics, it is native to the southwestern USA and has its own assemblage of indigenous seed beetles. The appearance of this South American seed predator in eastern California provides a new opportunity to examine the role novel competitors on the structure of competitive assemblages of seed beetles.