316 . E. G. LINSLEY 



can be demonstated to have been islands in the late Tertiary or 

 which are insular today (islands off the coasts of southern Califor- 

 nia and Baja California). Insect distributional patterns reveal a 

 similar discontinuity, not only among phytophagous wood-boring 

 forms but in such flightless groups as Pleocoma (Scarabaeidae) and 

 Omus (Cicindelidae). Among the Cerambycidae, this distribution 

 is evident in Megobrium edwardsi (LeConte), Ortholeptura insignis 

 (Fall) (hosts: Piniis muricata, P. radiata), and Paratimia conicola 

 Fisher (in cones of Pinus attenuata and P. holandari) . Other species 

 of the old California insular fauna apparently include Sternidocinus 

 barbarus (Van Dyke) and Necydalis barbarae Van Dyke. The 

 distribution of the former centers in the Santa Inez Mountains, 

 the latter in the region from Santa Barbara north to the Santa 

 Cruz Mountains. The Californian species Ipochus fasciatiis LeConte 

 and Atimia maritima Linsley, the Vancouveran Xylotrechus insginis 

 LeConte, and the widespread but austral Romaleum hispicorne 

 (Linnaeus) all occur today on one or more of the southern California 

 islands but, with the exception of the first two, give evidence of 

 being recent immigrants. 



SUMMARY 



Judging from an analysis of present day distribution and the 

 limited fossil record, the North American cerambycid fauna is a 

 complex of diverse elements of which five are rather readily identi- 

 fied: the Holarctic, Neotropical, Alleghenian, Vancouveran, and 

 Sonoran. The modern Holarctic and Neotropical constituents are 

 of relatively recent derivation, and endemism is expressed largely 

 at the species level. The Alleghenian, Vancouveran, and Sonoran 

 elements are of more ancient origin, although the first two were 

 apparently derived largely from an early Holarctic fauna associated 

 with the Arcto-Tertiary flora, the last almost entirely from the 

 early Neotropical. Much of the endemism in these subfaunas is at 

 the generic level. 



The modern Holarctic elements are more or less equally represen- 

 ted in the northern forests and mountainous regions of Europe, 

 Asia, and eastern and western North America. Their distribution 

 reflects Postglacial dispersal. Their hosts are largely conifers and 

 northern-type deciduous trees as Salix and Populus. In western 

 North America these are the dominant Cerambycidae of the 



