TACHINIDAE OF AUSTRALIA 25 



These are normally two, one behind the other, with the anterior one very 

 strong. The anterior one is, with the presutural seta, one of the most stable 

 and universally present setae in the tachinid chaetotaxy. Sometimes one or 

 two supernumerary supra-alars may be developed in addition to the normal 

 two, or the posterior supra-alar may be absent or hair-like. The second or 

 posterior sa seta is always present in Goniinae but is absent in such tribes as 

 the Phasiini and Palpostomatini and often in Ormiini. 



Some authors consider the pre-alar seta (pra) as the first of the supra-alar 

 setae and number the others accordingly (e.g. the posterior supra-alar is then 

 the third supra-alar), but this is an undesirably confusing terminology. When 

 both the pre-alar and the posterior supra-alar are absent (as in Phasiini and 

 Palpostomatini) the anterior supra-alar is the only seta present on the supra-alar 

 area and therefore stands very conspicuous and isolated. 



suprasquamal ridge. The weakly sclerotized area at the base of the postalar 

 wall to which the lower calypter is attached marginally (tympanic ridge of 

 Townsend) (Text-fig. 7). 



This structure is taxonomically useful according to whether it is bare or 

 haired. The suprasquamal ridge is bare in all Phasiinae and Goniinae, and 

 in the Proseninae hairing is confined to the Kutiliine genera Rutilia, Amphibolia 

 and Chrysopasta; the ridge is apparently bare in all Tachininae except Servillia 

 jakovlewii (Portschinsky). 



surstyli. The outer pair of articulated processes attached to the epandrium of 

 the male hypopygium (paralobes, outer forceps, tenth sternite lobes of Townsend) 

 (Text-figs 21 & 23). 



The form of the surstyli is of great taxonomic value at specific level but they 

 have relatively little taxonomic use at higher levels. 



tegula. The small anterior sclerite at the exteme base of the wing before the 

 basicosta (epaulet). 



tergites. The main segmental plates of the abdomen forming almost the entire 

 circumference of each segment. 



The tergites are taxonomically important in so far as their individual and 

 collective forms give shape to the abdomen and determine, for example, whether 

 it is elongate subcylindrical as in Cylindromyia and Doleschalla, or rather broad 

 and flattened as in many Phasiini and Rutiliini, or subovate as in the majority 

 of forms. In the Goniinae the ventral ends of the tergites meet in the mid- 

 line of the abdomen, but in many forms in the other subfamilies they do 

 not meet each other and the sternites are then exposed. Lengths of the 

 tergites relative to each other, special modifications such as the depression of 

 T5 found in many Rutiliini or the keel-like form of the abdominal venter in 

 some Blondeliini, and pollinosity and pattern on the tergites can all provide 

 useful characters. 



third costal sector. That sector of the costa lying between the apices of veins 

 R x and R 2 + 3 . 



transverse suture. An impressed line across the mesonotum dividing it into 

 anterior and posterior parts (prescutum and scutum, q.v.) (Text -figs 4 & 7). 



