CERAMBYCID BEETLE FAUNA 315 



Like the Sonoran, the "Californian" subfauna has southern 

 affinities but it is older, perhaps comparable in age with the Vancou- 

 veran. It exhibits relationship with elements now found in the mon- 

 tane phases of the Mexican Plateau, but, judging from the beetles, 

 at least some of its affinities suggest a closer relationship to the 

 contemporary faunas of the arid and semi-arid west coast of South 

 America (Peru, Galapagos, Chile, etc.) than to those of humid 

 tropical America. As has been emphasized previously (Linsley, 

 1939), it appears probable that some time during the later Tertiary 

 a series of arid or semi-arid environments permitted the dispersal of 

 elements between the west coasts of North and South America. 

 It is possible that these environments were associated with mountain 

 ranges or chains of islands. At present, portions of the peninsula of 

 Baja California and the islands off the coast of southern California 

 exhibit arid (landward) phases and humid (seaward) phases, the 

 former usually characterized by desert or semi-desert conditions, 

 and Michener (1954) has emphasized that xeric communities now 

 exist in the vicinity of the Canal Zone in Panama. Such arid phases 

 might well have offered north-south dispersal routes for plants and 

 animals. 



Among the Cerambycidae, a typical Californian genus is Ipochus, 

 a wingless group of closely related species or subspecies which 

 occupies an area from the middle of Baja California north to Santa 

 Cruz, California, including Guadalupe and Catalina islands, and 

 is also represented in the Huachuca Mountains. Other groups with 

 southern (but not Sonoran) affinities, apparently assignable as 

 endemics of the Californian in the broad sense, include the mono- 

 typic genera Megobrium, Eiidistenia, Meganoplium, Paranoplium, 

 Hesperanoplium, Neobellamira, Triododytus, and Sternidocinus 

 (associated primarily with oaks and chaparral shrubs); Vandykea, 

 which is attached to Sargent Cypress; Eucrossus and Haplidus, 

 occurring primarily with pinyon pine; and the polytypic genus 

 Poliaenus, with one species limited to Fremontia (a chaparral type), 

 others to pinyon and digger pines (woodland types). 



The California insular fauna has been treated as a subdivision 

 of the Californian, but among the Cerambycidae, except as noted 

 for Ipochus (above), no endemic elements are known and typical 

 Californian elements are present (Fig. 2). Mason (1934) has shown 

 that the modern closed -cone pine forest now occupies areas that 



