jecting above eye in profile; 2 ors, 3 ori; gena 
not extended at rear, rounded in front, slightly 
projecting forward, about 0.25 height of eye; 
single strong vibrissa present; antennae divided 
by low facial keel; mesonotum shining black, with 
2 dc; wing length in male 2.4 mm, costa extending 
to vein M 1+2, inner crossvein at distal 3d of 
discal cell, outer crossvein less than own length 
from inner; male genitalia with aedeagus as in 
figures 189, 190; epandrium and cercus as in 
figure 191. 
Host/Early Stages. Tilia americana . Larva forming 
oval twig gall, several galls adjoining on same 
twig (fig. 192). 
Distribution. Illinois, Indiana, Missouri, 
Pennsylvania, Virginia. 
References. Couden, 1908: 34 (description and bi- 
ology); Frick, 1959: 367 ( as Melanagromyza ) ; 
Spencer, 1981: 33 (as Hexomyza ) ; part 2, p. 260. 
17 (14). Gena broad, almost 0.25 height of eye — — 
“ 0 . fastosa (Spencer) 
Synopsis. Closely resembling 0. abutilivora , pos- 
sibly generally larger, wing length up to 2.8 mm; 
gena broader (fig. 193); male genitalia as in 
figures 194, 195. 
Host/Early Stages. Unknown, possibly Brassica . 
Distribution. Colorado (new record); Canada. 
References. Spencer, 1969a: 67; part 2, p. 255. 
Gena narrow, 0.17-0.14 height of eye 18 
18 (17). Male genitalia with aedeagus as in figures 197, 
198 0. abutilivora Spencer, n. sp. 
Synopsis. Small black species, wing length 2-2.3 
mm; head as in figure 196; brilliantly shining 
ocellar triangle; mesonotum and abdomen without 
any greenish reflections. 
Host/Early Stages. Abut i Ion theophrasti, Sida cor- 
difolia . Larva forming raised, external stem mine 
or "welt," pupating in stem with anterior spir- 
acles projecting through epidermis; puparium straw 
colored, posterior spiracles (fig. 199) each with 
4-6 bulbs. 
Distribution. Florida, Illinois, Minnesota, 
Mississippi, Wisconsin. 
Reference. Part 2, p. 250. 
Male genitalia with aedeagus as in figures 200, 
201 0 . parvella (Spencer) 
Synopsis. Small black species, not distinguishable 
on external characters from 0. abutilivora . 
Host/Early Stages. Unconfirmed, possibly Lantana. 
Larva forming long, pale leaf mine (fig. 202) , 
pupating in leaf. 
Distribution. Florida; Bahamas. 
References. Spencer and Stegmaier, 1973: 46; part 
2, p. 256. 
19 (10). Orbital setulae proclinate; ors lacking in male 
0. nasuta (Melander) 
42 
