444 



Wirth and Stone: Diptera 



Fig. 14:48. Tabanidae. a, Chrysozona americona (O.S.), larva; b, Atylotus inci sural i s (Macq.), 

 larva; c, Silvius quadrivittatus (Say), wing; d, Pilimas californica (Bigot), head of female; e, 

 Apatolesles comosfes Will., head of female; f, Tabanus tetricus Mar., pupa; g, Cbrysops discalis 

 Will., larva (c,d,e, Brennan, 1935; a,b,f,g, Cameron, 1926). 



North American subfamilies, and Philip (1947) pub- 

 lished a catalogue of the Nearctic species with a key 

 to the genera. The early literature on the larvae and 

 pupae was reviewed by Marchand (1920), and later 

 papers on the biology and immature stages are by 

 Stone (1930), Webb and Wells (1924), and Cameron 

 (1926). The California species have been treated by 

 Middlekauff (1950). 



Key to Nearctic Genera of Tabanidae 

 Adults 



1. Hind tibiae with 2 apical, usually strong spurs (weakest 

 in the rare Merycomyia); subepaulets bare, uninflated 

 (PANGONIINAE) 2- 



— Hind tibiae without apical spurs (TABANINAE) .12 



2. Antennae 9-10 segmented (flagellum with at least 7 

 divisions, the basal one not greatly differentiated) 

 (PANGONIINI) 3 



— Antennae with not more than 7 segments (flagellum with 

 at most 5 divisions, the basal one considerably elon- — 

 gated) (fig. 14:47e); proboscis seldom exceeding height 

 of head 8 n 



3. Eyes of female with upper angles sharply acute; wings 

 with a wide, sharply marked, irregular brown pattern 



Goniops Aldrich — - 



— Eyes above at most rectangulate; wings hyaline or 

 diffusely tinted 4 



4. Proboscis hardly 1/2 the height of the head; palpi 12 

 usually shorter than the antennae and swollen basally 

 (fig. 14:48c) 5 — 



— Proboscis about equal to height of head (fig. 14:48a"); 

 palpi subequal to length of the antennae, 1/2 or less 

 that of the proboscis, not swollen basally 6 



'Adapted from Philip, 1947. 



5. Eyes bare Apatolestes Williston 



— Eyes and body abundantly pilose Brennania Philip 



6. Cell R s closed and petiolate Esenbeckia Rondani 



— Cell R s open at wing margin 7 



7. Eyes hairy (short in female); base of vein R 4 with short 

 spur Pilimas Brennan 



— Eyes bare; R 4 often without spur ... Stonemyia Brennan 



8. Flagellum with 5 divisions (fig. 14:47a); usually slen- 

 der, often picture-winged flies (CHRYSOPINI) 9 



— Third antennal segment with 3 divisions (MERYCO- 

 MYIINI) Merycomyia Hine 



9. Eyes in life (or relaxed) "freckled" with small rounded 

 spots; pedicel of antenna either about 1/2 the length 

 of the scape or distinctly longer than the flagellum; 

 wings hyaline or with isolated clouds on cross veins 

 (fig. 14:48c) 10 



— Eyes in life (or relaxed) with large angular spots; 

 scape and pedicel usually subequal, the flagellum as 

 long or longer than either; wing usually with irregular, 

 extensive dark pattern 11 



10. Flagellum of antenna much shorter than either of the 

 basal segments and shaped like a bowling pin with a 

 bent neck; pedicel nearly as long as scape 



Assipala Philip 



■ Flagellum at least longer than pedicel, the latter only 



about 1/2 as long as scape Silvius Meigen 



Abdomen globose, much wider than thorax, wings 

 evenly fumose, a spur at base of vein R 4 



Neochrysops Walton 



Abdomen slender; wings mostly with irregular dark 

 patterns, no spurs (except adventitiously) (fig. 14:47c) 



Chrysops Meigen 



Subepaulet (basicosta) bare and flat in Nearctic 

 species 13 



— Subepaulet with hairs like those on the costal vein; 

 often inflated 17 



13. Labellae sclerotized, smooth and shining 14 



— Labellae fleshy, shrunken and distorted when dry 

 (DIACHLORINI) 15 



