CERAMBYCID BEETLE FAUNA 317 



Canadian and Hudsonian life zones, but they are also represented 

 in the coniferous phases of the Transition and Upper Sonoran. 



The recent Neotropical elements, derived from areas of high 

 temperatures and humidity and attached largely to southern-type 

 hardwoods and Leguminosae, have penetrated northward very 

 unequally. They are largely restricted to the Austro-Riparian belt 

 bordering the Gulf of Mexico, the Atlantic coastal plain, and a few 

 warm river valleys like those of the Mississippi, the lower Rio 

 Grande, and the lower Colorado. About a half-dozen wide-ranging 

 species in this category reach southeastern California. 



The Vancouveran elements, in their purest form, occur along the 

 coast of western North America from the Aleutian Islands to 

 Central California, in more dilute form in the Bitter Root and north- 

 ern Rocky Mountains, the Cascades, Sierra Nevada, San Ber- 

 nardino, San Jacinto, and San Pedro Martir Mountains. These are 

 the dominant Cerambycidae of the Transition Life Zone and they 

 show closer affinities with those of Europe and eastern Asia than 

 with their Alleghenian counterpart in eastern North America. 



The endemic Sonoran elements are almost entirely of early 

 Neotropical derivation and exhibit various modifications of structure 

 and habit associated with the arid conditions under which they now 

 exist. They are characteristic of the Lower Sonoran Life Zone and 

 occupy most of the central and northwestern plateaus of Mexico, 

 western Texas, much of New Mexico and Arizona, southeastern 

 California and eastern Baja California and are associated with 

 desert trees, shrubs, and Cactaceae. A major derivative of the 

 Sonoran fauna occupies the intermountain area of the Great Basin. 

 It is dominated by genera associated with the roots of shrubby 

 Compositae (as Artemisia and Chrysothamnus) and asclepiads. 



A small endemic cerambycid subfauna with southern affinities 

 occurs from Monterey County, California, to the middle of the west 

 coast of Baja California and in the interior from the Techachapi 

 area to the San Pedro Martir; its influence is also seen in the foothill 

 areas surrounding the central valley of California and in some of 

 the mountain ranges of southern Arizona. This subfauna, sometimes 

 called the " Calif ornian," also has an insular phase. Some affinities 

 with the subfauna now occurring along the arid west coast of South 

 America but the Calif ornian also has characteristics of its own, 

 and about a dozen endemic cerambycid genera, mostly mono- 



