TACHINIDAE OF ORIENTAL REGION 49 



Wing with cell Z? 5 open or closed just at the wing margin. Pleural regions of the 

 thorax with black or brownish black hair (occasionally some pale hair ventrally 

 in Dexia). Head with a facial carina (except in some Billaea species). Bend of 

 vein M nearly always much closer to the wing margin than to m-cu ... 4 



Wing with cell R h closed and petiolate, the petiole about as long as r-m. Pleural 

 regions of the thorax with white or yellowish white hair. Head without a facial 

 carina. Bend of vein M much nearer to m-cu than to the wing margin 



DOLICHODEXIA Brauer & Bergenstamm 



Second costal sector of the wing haired ventrally ...... 5 



Second costal sector of the wing bare ventrally . ... . . . 6 



Propleuron bare (excepting caldwelli in which a few minute hairs present medially). 



Head with a facial carina. Palpi not flattened .... DEXIA Meigen 



Propleuron fully haired. Head without a facial carina. Palpi distinctly flattened 



along their length ........ Undetermined genus 



[Running out here is a single undescribed species from Malaya that cannot be 

 satisfactorily placed to a genus at present. It is a large species with facies 

 somewhat intermediate between Dexia and Billaea.] 



Two prst dc setae. Prescutum without clearly differentiated acrostichal setae. 

 Pre-alar seta absent. Wing with veins R t ^ - and M x ending almost at the wing- 

 apex and with the second costal sector exceptionally short (about half as long as 

 the first sector and subequal in length to m-cu). Very small forms, length not 

 exceeding 6 mm ........ TYLODEXIA Townsend 



Three or more prst dc setae. Prescutum with strong acrostichal setae (usually two 

 pairs). Pre-alar seta present. Wing with veins R i+i and M, ending as usual 

 distinctly basad of the wing-apex and with the second costal sector not unusually 

 short (more than half as long as the first sector and longer than m-cu). Larger 

 forms, length at least 8 mm and usually much more ..... 7 



Propleuron bare. <$ head with eyes almost meeting, upper part of interfrontal area 

 obliterated and frons at its narrowest not more than twice as wide as the anterior 

 ocellus. Head with facial carina of characteristic shape, the carina narrow 

 between the antennae but widening towards its ventral end and then contracting 

 again to the epistome. ..... MYOSTOMA Robineau-Desvoidy 



Propleuron haired, q head with eyes well separated, upper part of interfrontal area 

 not obliterated by meeting of the parafrontals, frons at its narrowest at least four 

 times as wide as the anterior ocellus. Head with or without facial carina, if 

 present then differently shaped (with subparallel sides, subfusiform, or more or 

 less regularly widening towards the epistome) ...... 8 



Three post dc setae (a supernumerary fourth hair-like post dc rarely interposed 

 between the first and second seta). Facial carina present, rather sharp and 

 narrow. Abdominal Ti + 2 with a pair of strong median marginal setae in the 

 <J, without median marginal setae in the 9- Mainly slender Dexia-hke forms with 

 very long legs ............ 9 



Four strong post dc setae. Facial carina present or absent, when present almost 

 always rather broad (wider than the third antennal segment). Abdominal Ti + 2 

 without median marginal setae in both sexes. Mainly robust forms with the 

 legs not unusually elongate and often with the facies of large Sturmiini 



BILLAEA Robineau-Desvoidy 



Abdominal T3 and T4 without discal setae. Profrontal region of the head bare. 

 Bend of vein M extremely close to wing margin (distance from bend to margin 

 about equal to the length of r-m). Forms with the abdomen largely yellow or 

 reddish yellow and with the femora and usually much of the tibiae reddish-yellow. 

 [Malaysia, western Indonesia, Philippines] ....... 10 



Abdominal T3 and T4 with strong erect median discal setae. Profrontal region of 

 the head black-haired. Bend of vein M not very close to wing margin (distance 



