232 PROCEEDINGS OF THE NATIONAL MUSEUM vol. in 



Geographical Distribution ^ 



Ogcodes is a cosmopolitan genus comprising 88 species and sub- 

 species. These forms are found in the various regions as follows: 

 Australian, 23; Ethiopian, 12; Nearctic, 18; Neotropical, 9; Oriental, 

 10; Palaearctic, 19; Polynesian, 3. There are several important areas 

 where Ogcodes species have either not been collected or where they 

 have been unable to reach and adapt. As shown in text figure 1, 

 species are absent from such islands as Madagascar, West Indies, 

 Greenland, Iceland, Ireland (?), Canaries, Sumatra, Borneo, Celebes, 

 New Guinea, Formosa, Hawaii, and apparently all the smaller mid- 

 oceanic islands, as weU as from most land areas north of the Arctic 

 Circle and south of the Antarctic Circle. That Ogcodes species have 

 not been barred from adapting themselves to island faunas is attested 

 by the fact that they occur in England, Ceylon, Java, New Zealand, 

 Tasmania, the Philippines, and Juan Fernandez Islands. Besides 

 Ogcodes species not populating certain islands, they are apparently 

 satisfactorily barred from all the major desert regions of the world. 



The great majority of species are restricted to a single region. 

 Notable exceptions are Ogcodes guttatus Costa, which inhabits the 

 Ethiopian, Oriental and Palaearctic regions, and 0. dispar (Macquart) 

 and 0. pallidipennis Loew, which occur both in the Nearctic and 

 Neotropical regions. Although there are no known truly Holarctic 

 species, 0. eugonatus Loew, 0. melampus Loew [both Nearctic], 0. 

 nigripes (Zetterstedt), and 0. zonatus Erichson [both Palaearctic], are 

 extremely closely related (see discussion under the Nearctic species). 

 A further complication of this association is the fact that 0. caffer 

 Loew from the southern Ethiopian region is also very similar. 



Of the three subgenera recognized, only Ogcodes Latreille is cosmo- 

 politan. Neogcodes, new subgenus, is restricted to the Nearctic sub- 

 region and Protogcodes, new subgenus, is an Australian endemic. 



Concerning the subgenus Ogcodes, which contains 86 of the 88 

 species, I found considerable specific morphological evidence that 

 aided me in determining the geographical relationships of the species. 

 This was most easUy accomplished through studjdng the six species 

 groups (p. 249). 



The pallidipennis group is widespread, occmTingin all areas except 

 the New Zealand subregion. It appears to be most common, however, 

 in the Holarctic, Oriental and Australian regions, having apparently 

 never reached New Zealand, and is not very common in the Ethiopian 

 region. 



The colei group is also widespread but in a much more restricted 



8 The divisions of geographical regions adopted here follow that outlined by Beaufort (1951) for the most 

 part. I have, however, made subreglons out of his Australian, New Zealand, and Oceanic Islands regions 

 and changed the last-named region to Polynesian subregion. 



