348 PROCEEDINGS OF THE NATIONAL MUSEUM vol. io8 



The North American species are distributed throughout 15 genera 

 and 11 subgenera. Except for Xyraeomyia and possibly Haplomyza, 

 all are Holarctic. Several very small genera, mostly monotypic, are 

 not found in North America. These are the Neotropical Triticomyza 

 Blanchard and the Palaearctic Carina gromyza Sasakawa, Gymno- 

 phytomyza Hendel, Ptochomyza Hering, Selachops Wahlberg, and 

 Xeniomyza de Meijere. Each genus is redescribed and separated by 

 the use of illustrated keys giving full consideration to the unusual 

 species peculiar to North America. These unusual species are dis- 

 cussed under their respective genera. The similarities and differences 

 between the faunas of North America and the Palaearctic region, the 

 two best collected regions in the world, are also taken up under each 

 genus. 



It might be noted here, however, that the northern Neotropical 

 region, poorly collected though it is, has contributed more than its 

 proportionate number of extraordinary species. Among these are 

 the reddish lunule and lower frontal vitta of Melanagromyza diadema, 

 the white spot on the halter of Ophiomyia punctohalteraia, the yellow 

 scutellum of Phytobia (Phytobia) pida, the pictured wing of P. (P.) 

 kallima, the yellow third antennal segment of P. {Caly corny za) 

 meridiana, the distally narrowly yellow femora of P. (C.) cassiae, 

 P. (C) ipomoeae, and P. (C.) lantanae, the enlarged thu'd antennal 

 segment of males of Liriomyza commelinae, and the very large (3.5 to 

 4 mm. in wing length) South American L. brazilicnsis Frost and L. 

 ecuadorensis Frost that have posterolateral setae medially on the 

 midtibia and have larvae that mine the tubers and sometimes the 

 stems of Solanum tuberosum Linnaeus. 



Two species groups that are all or nearly all Neotropical have 

 representatives in the southern Palaearctic region also. The first of 

 these is the viridula group in the genus Agromyza. There are four 

 northern Neotropical species and one from eastern United States. 

 There appear to be two Palaearctic species: Agromyza salicifolii 

 Collin does not occur north of Israel, and A. quercus Sasakawa occurs 

 in Japan. A similar situation is found in Melanagromyza. There are 

 five Neotropical representatives in the puHcaria group. The two 

 Palaearctic species occur in the southern extremities of that region and 

 one, M. inaequabilis Hendel, is not found as far north as Em'ope while 

 the distribution of M. pulicaria Meigen includes Europe. 



The morphological characters used in the keys and descriptions were 

 described by Frick (1952). The only change made in that system is 

 the renumbering of the dorsocentral setae. Hendel (1931) numbered 

 from the posterior of the mesonotum forward and Frick (1952) ac- 

 cepted that arrangement. However, in 1953 Frick (1953b) rejected 

 that svstem and counted from the anterior to the posterior or scutel- 



