HORSEFLIES OF THE SUBFAMILY TABANINAE 
Key to Nearctic Females of Tabanus—Continued 
136. Stout species about 12 mm in length; sublateral abdominal spots 
yellowish ; no stump vein present_fretus, new species, p. 154. 
More slender species, 13 mm or more in length; sublateral ab- 
dominal spots grayish; a rather long stump vein from vein 
Ra usually present! vss seen ee et liorhinus Philip, p. 155. 
187. (135) Stump vein from vein R: usually present; length 15 mm or more; 
subeallus rarely entirely denuded; frons usually over three 
and one-half times as high as width at base 
hirtulus Bigot, p. 159. 
Stump vein usually absent; length 14 mm or less; subcallus 
entirely denuded; frons about three times as high as width 
at PASC Ish ALE SOs ye TOP ae melanorhinus Bigot, p. 156. 
138. (182) Legs nearly uniformly yellowish brown; (second palpal segment 
stout at base, but tapering to a slender apex; dorsal angle of 
third antennal segment inconspicuous) ——~-____--________-- 
Memora entirely, black “or ‘grayish’ 2-42 soe Ee 
139. Prescutal lobe black; frons rather narrow 
microcephalus Osten Sacken, p. 156. 
Preseutallobe reddish ;-frons broad—__-~-_---___.---—-____.__ 
140. Sublateral abdominal spots rather broadly surrounded by orange 
brown; frons about three times as high ag basal width; sub- 
eallus dark brown; costal cell brownish; hind tibial fringe 
| OGY G be See RSE ELS 2 A a brennani, new species, p. 157. 
Abdomen without much orange brown laterally; frons about 
twice as high as basal width; subcallus yellowish brown; 
costal cell hyaline; hind tibial fringe largely white 
itasca Philip, p. 158. 
141. (188) Prescutal lobe black; stout species, with a faint spot at furcation 
and considerable orange brown on sides of tergites 
atrobasis McDunnough, p. 159. 
Prescutal lobe usually reddish brown, or, if black, more slender 
species, with little reddish laterally on tergites___-_________ 
142. Length 15 mm or more; a stump vein near fureation usually pres- 
ent: pollen of head gray _—__=_ = _ = _ = hirtulus Bigot, p. 159. 
Length usually less than 15 mm; stump vein rarely present; part 
of head usually faintly tinged with yellowish_______________ 
148. Frons rather broad and distinctly widened above; sublateral, pale, 
abdominal spots distinct, oblique, yellowish brown, their me- 
dian markins usually slightly concave_opacus Coquillett, p. 160. 
Frons narrower and scarcely widened above; sublateral pale 
spots variable, but if distinct and yellowish, more nearly 
round, with median margins straight or convex___-_________ 
144. Sublateral abdominal spots large, contiguous and yellowish 
frontalis Walker, p. 161. 
Sublateral abdominal spots small, usually grayish and not con- 
USO S ae SOE ee nS pe ere septentrionalis Loew, p. 162. 
Key to Nearctic Males of Tabanus 
1 DDR | OVE Sak 0 an 
Vee pllOSe rare: SEM RG Ne ES) es ee 
De Hair on mid line between eye______-- carolinensis Macquart, p. 126. 
INOshaingbetweenweyess: a at Fe 
3. Abdomen unicolorous or with narrow, indistinct, pollinose bands__ 
Abdomen not unicolorous; if bands are present, they are broad 
and distinct 
4. Palpustorance- brown: -to® white-=-2-0 0-2 ee 
Ralpus’ dark-brown toe blacks a0 
5. Fureation with a distinct brown spot________ imitans Walker, p. 86. 
Fureation not margined with brown__________--__-_-__--__-_____ 
6. Hind tibial fringe orange; wing mostly hyaline 
americanus Forster, p. 83. 
Hind tibial fringe black; wing dilute brownish 
giganteus Degeer, p. &4. 
7. (4) Furcation without an infuscated spot although the whole wing may 
Furecation with a distinct brown spot____________-_-_-_-_-_ na 
47 
139 
141 
140 
142 
143 
144 
