1 



Geographical Origins and Phylogenetic Affinities 

 of the Cerambycid Beetle Fauna 

 of Western North America 



E. Gorton Linsley 



University of California, Berkeley 



1 he two previous papers deal with dis- 

 tributional patterns, respectively, of groups of cool-adapted an- 

 imals, including northern and montane insects, particularly caddis- 

 flies and sawfhes, and of certain free-living terrestrial forms (Orth- 

 optera and Dermaptera). The Cerambycidae, or long-horned 

 beetles, as larvae, are mostly internal feeders in living, dead, or 

 dying woody plants, a fact that has greatly influenced the dis- 

 tributional and evolutionary history of the family. Nearly 900 

 species are now known from America north of the Mexican bound- 

 ary. The adults of a few groups are flightless, but most are relatively 

 strong but somewhat inefficient fliers. They seek the appropriate 

 host plant before or after mating and subsequently oviposit in 

 cracks or crevices in the bark or in notches cut by the female. 

 The degree of host specificity varies. The forms that attack living 

 trees and assemble on the host plant for mating usually exhibit the 

 greatest specificity, and those that attack dead or decomposing 

 wood, the least. The fact that many of the latter group congregate 

 on flowers for mating precludes or weakens selection for host 

 specificity. Thus the close association of Cerambycidae with woody 

 plants and the varying degrees of intimacy in relation to particular 

 trees and shrubs must be considered in any analysis of the origins 

 and affinities of the North American elements of the family. 



Based on analyses of contemporary distributions, on phylogenetic 

 and ecological relationships, and on the limited fossil record, the 

 North American cerambycid fauna appears to be a complex of 

 diverse distributional elements or subfaunas, of which five are 

 rather readily identified: a Holarctic element (largely Ijoreal), 



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