26. 
(18) 
27. 
28. 
29. 
30. 
31. 
32 
30 
. (30) 
. (16) 
34. 
36. 
37. 
38. 
39, 
40. 
(38) 
ail, 
42. 
43 
. (40) 
HORSEFLIES OF THE SUBFAMILY TABANINAE 
Key to Nearctic Males of Tabanus—Continued 
Venter of abdomen with rather broad bands along posterior margins 
of sternites, distinctly paler than basal portions of sternites__ 
Venter of abdomen nearly uniformly brownish, the apical pale 
bands narrow-and-not.contrasting=22222 25 eee 
Stump rvein=trom) vem We) 2Gie — Bete ve lacustris Stone, p. 104. 
INOFStUMIp Vein inom Veins ae ees eae 
Tibiae bright orange, with concolorous hair 
trijunctus Walker, p. 107. 
TMibiaes other wises. soe tins ee us endymion Osten Sacken, p. 108. 
Costaltcellthyalineseiee® 2 eee equalis Hine, p. 1138. 
@Costaleells- distinctly: colored. 22h oe eee eae AEX AED ANS Ga 
egsanearly, uniformly. orange: browne. 2222s See 
AG RACASE HHEIMMOTAl LACK. Came Fite EET ee Vy A RE ESE 
Abdomen orange brown, the median triangles not very distinct, 
that on second tergite with a narrow black spot anterior 
Oe 0 ee eee eee ea Pe cheliopterus Rondani, p. 109. 
Abdomen dark brown, with narrow, elongate, whitish triangles 
recedens Walker, p. 110. 
Areas of large and small facets of eye distinctly differentiated 
sulcifrons Macquart, p. 114. 
Facets of eye nearly uniform in size, the areas not sharp dif- 
Lene bated + eee 2 gladiator Stone, p. 85. 
Some tergites with three pale spots; spots of median row some- 
times contiguous but not forming a parallel-sided stripe_____ 
Abdomen with a well defined, parallel-sided, median, pale stripe__ 
Wing mottled with brown, the spots not confined to cross veins or 
fureation; tergites 2-4 with posterior white bands nearly 
obliterating the median and sublateral spots, but the spots 
distinetron tergite 426 208 85 venustus Osten Sacken, p. 78. 
Not iwithethisicombination of characters___ 2222-2 22 
Fureation and cross veins margined with brown 
cymatophorus Osten Sacken, p. 80. 
Wing entirely hyaline or with a faint spot at furcation only, or all 
veinsstaintly= margined with’ brown22220e laoe) oe ses 
Fore tibia entirely black______________ nivosus Osten Sacken, p. 64. 
Horerstipiaupalewatleast:on., basal half. ..2 
No median white spot on tergite 2, but spots on tergites 3 and 4 
very conspicuous; sublateral spots oblique and those on ter- 
gites 4-6 indistinct; first antennal segment with a well devel- 
opedvdorsalvangle® 2.25 Oa! w oe fo a dorsifer Walker, p. 56. 
Not wathethis+combination-of charactersz-22) 20)" eos 
Blackish species, 10 mm or less in length; costal cell hyaline; 
sublateral abdominal spots rounded and usually completely 
separated from posterior margins of tergites________-________ 
Brownish, yellowish, or blackish species, 12 mm or more in length, 
or, if less, the costal cell brown; sublateral abdominal spots 
usually reaching posterior margins on some tergites__________ 
Third antennal segment with distinct dorsal angle; (eastern part 
i pumilus Maequart, p. 75. 
of the United States) -----------__. sparus Whitney, p. 77. 
Third antennal segment slender, without distinct dorsal angle; 
(western part of the United States) _fratellus Williston, p. 76. 
Costal cell dark brown or deep yellow______________~-_---______- 
Costal cell hyaline or faintly tinged with yellow___-_-_____-______ 
Antenna entirely light orange______________ eythicolor Philip, p. 69. 
Antenna with basal portion of third segment orange, annulate 
DOTLMONE ID) a Ckveaen wim R Ee i is Ne ANS ee 
Sublateral abdominal spots angular and contiguous 
teranus Hine, p. 70. 
Sublateral abdominal spots rounded and not touching hind margins 
OME SLES ee IN ds PO et longiusculus Hine, p. 71. 
Hair and pollen of pleura yellow; areas of large and small facets 
of eye weakly differentiated_______ fulvulus Wiedemann, p. 55. 
38521°—38—4 
49 
28 
30 
fod 
34 
36 
oT 
38 
40 
41 
43 
42 
