368 PROCEEDINGS OF THE NATIONAL MUSEUM vol. los 



features (fig. 44) but the antennae are separated by one-half the di- 

 ameter of a basal antennal segment. The type female from Maryland 

 is the only known specimen. 



3. Genus Ophiomyia Braschnikov 



Ophiomyia Braschnikov, Ann. Inst. Agr, Moscow, vol. 3, p. 40, 1897. 



This is a relatively small genus that is characterized by having the 

 halteres black, the orbital setulae reclinate, and a fusiform carina 

 between the antennae (fig. 45). The males of all but one European 

 species have a fasciculus at the vibrissal angle (fig. 51). This fas- 

 ciculus may be composed of only a few setae (fig. 47) or it may be 

 very short (fig. 48). The vibrissa of the females is always a single seta 

 (fig. 52). There are 11 North American species of which four are 

 Neotropical, five are Nearctic, and two ar^ found in both regions. 

 Three species are Holarctic, with one, 0. proboscidea, extending into 

 Central America. 



None of the North American species has the costa reaching only to 

 R4+5, while 7 out of 13 Palaearctic species have the costa abbreviated. 

 0. punctohalterata is unique in having a white spot on the knob of the 

 halter. 



There is one group of species that is sufficiently closely related to 

 be called a species group, the proboscidea group (couplet 3). These 

 species have the vibrissal angle extended anteriorly into an acute 

 angle (figs. 48, 51, 53, 54). The remaining species are widely divergent 

 from one another. 



Key to the described species of Ophiomyia 



1. Halter black 2 



Halter with a white spot on the knob punctohalterata 



2. Head, viewed in profile, with a vibrissal angle of 45° to 60° (fig. 51) .... 3 

 Head, viewed in profile, with a vibrissal angle of about 90° (fig. 49) .... 5 



3. Head with subcranial margin straight (figs. 48, 51) 4 



Head with subcranial margin curved (figs. 53, 54) texana 



4. Anterior half of mesonotum with six to eight rows of acrostichal setae; head 



with vibrissal angle about 60° (fig. 51) proboscidea 



Anterior half of mesonotum with nine to ten rows of acrostichals; vibrissal 

 angle about 45° (fig.48) coniceps 



5. Head, viewed in profile, with gena narrow, midwaj' between vibrissal and 



posterior angles from one-fifth to one-eighth the eye height (fig. 49) ... 6 



Head, viewed in profile, with gena wide, midway between vibrissal and 



posterior angles about one-third the eye height major 



6. Calypter with margin and fringe dark brown to black 7 



Calypter with margin and fringe whitish buscki 



7. Anterior half of mesonotum with acrostichal setae in nine to ten irregular 



rows 8 



Anterior half of mesonotum with acrostichal setae in six to eight irregular 

 rows 9 



