TACHINIDAE OF AUSTRALIA 15 



character (but great care is often needed in examining them as they are easily 

 overlooked). They occur haphazardly in various genera in all the subfamilies 

 but are of rare occurrence in Goniinae (mainly confined to some Blondeliini) 

 and Proseninae (but occurring at least in some Chetogaster) . 



inner vertical setae. The main pair of erect setae standing on the summit of the 

 vertex (Inner -e Stirnborsten of Mesnil) (Text-fig. 3) . 



This pair of setae is almost universally present in Tachinidae, though it is 

 sometimes weak and hair-like in Phasiinae and some aberrant tribes. The two 

 setae are most often subparallel to each other but are sometimes directed inwards 

 and crossed, especially in some Tachininae. Subparallel inner verticals are the 

 rule in Goniinae though genera with cruciate inner verticals occur (e.g. 

 Phorocerosoma) . 



interfrontal area. The median area of the frons between the parafrontals 

 {inter frontalia, frontalia, frontal vitta, Stirnstrei/en of Mesnil) (Text-fig. 2). 



In forms in which the head is holoptic or the eyes strongly approximated 

 the interfrontal area is extensively obliterated and the parafrontals meet in 

 part in the mid line of the frons. 



intermediate abdominal tergites. The middle two of the apparent four main 

 abdominal segments when seen from above, i.e. tergites 3 and 4 collectively. 



intra-alar setae. The setae of the mesonotum standing external to the dorso- 

 central setae and approximately in line with the middle of the postalar 

 callus (Text-fig. 4). 



The number and arrangement of these setae are of great taxonomic 

 importance. The most complete complement (excluding the occasional haphazard 

 supernumerary) is 1 + 3 ia setae and is found in the great majority of Goniinae. 

 The presutural intra-alar is most often absent in the other subfamilies but is 

 present, for example, in Voriini and Campylochetini (which have a 1 + 3 ia 

 complement like most Goniinae) and sometimes elsewhere. Many Phasiinae 

 and a few Tachininae have two strong posterior intra-alars that are widely 

 spaced with the anterior one close to the transverse suture, e.g. Leiicostoma, 

 Cylindromyia, Zita, Lever ella; this arrangement of two post ia is fundamentally 

 different from that found in forms normally possessing three but occasionally 

 lacking the anterior one (in which case the two remaining post ia stand near 

 each other and the front one is remote from the transverse suture). A few 

 forms completely lack intra-alar setae (e.g. some Phasiini and Ormiini) or they 

 may be missing in isolated specimens of species normally possessing at least 

 one. In Cylindromyia the anterior one of the two post ia is enormously strong 

 and stands out of alignment with the hind one and unusually close to the 

 pre-alar seta. 



last section of Cu v The part of vein Cu x between its junction with m-cu and its 

 apex at the wing margin. 



lateral scutellar setae. One or more pairs of marginal scutellar setae standing 

 between the basal and subapical or apical pairs (Text-fig. 5). 



These setae are frequently absent, and when present are usually weaker than 

 the basals and subapicals. ■ 



