TACHINIDAE OF AUSTRALIA 13 



taxonomic importance at several levels in different parts of the family. Often 

 the depression extends backwards to reach the end of the segment, in which 

 case Ti + 2 is described as 'excavate to its hind margin', but in many forms 

 the depression clearly falls short of the hind margin or there is virtually no 

 depression at all (e.g. many Phasiinae, Doleschallini). When Ti -f- 2 is excavate 

 to its hind margin this condition often holds true of all the members of a tribe 

 (e.g. all Rutiliini, all Sturmiini); in other tribes (e.g. Blondeliini) the tergite 

 may be excavate to its hind margin in some genera but not others. In many 

 Prosenini the excavation is rather deep and narrow and the sides of Ti + 2 

 are rather strongly humped. 



face. The anteromedian surface of the head below the antennae and between the 

 facial ridges (clypeus of Townsend) (Text-fig. 2) . 



facial carina. A strong median vertical ridge on the face separating the antennae 

 (facial keel) (Text-fig. 12). 



The presence or absence of a facial carina, and its form when present, provide 

 important key characters for recognition of some forms. In most Tachinidae 

 the face is flat or only weakly raised medially, but a large facial carina is present 

 in many Proseninae (Prosena, Senostoma, Billaea and all Rutiliini). When a 

 carina is present it is typically flattened or convex on its anterior surface, or 

 prominently bulbous on its upper part and contracting to a sharper ridge 

 towards the lower end, but a sharp roof-like carina occurs in Euthera. A true 

 facial carina is absent in Tachininae and Goniinae, but a weak swelling may be 

 present below and between the antennal bases (e.g. in Macrochloria). 



facial profile. The anterior outline of the head between the antennal base and 

 the epistome when viewed in profile. • 



facial region. The face, facial ridges and parafacials collectively. 



facial ridges. The flattened or raised strips differentiated on each side of the 

 face that separate it from the parafacials (facialia) (Text-fig. 2). 



These are of great importance in taxonomy because of their variously modified 

 form (whether ridge-like lateral margins to the sunken face or flattened and 

 in the plane of the face), the extent of their visibility when the head is viewed 

 in profile, and the extent to which they bear hair or setae. In many aberrant 

 forms (e.g. Therobia, Myiotrixa) they are widened and flattened ventrally and 

 extensively haired, but typically they are at least slightly ridge-like and have 

 at least a few setulae immediately above the vibrissae (which in normal forms 

 demarcate the ventral ends of the ridges); in many genera of Tachininae and 

 Goniinae the ridges bear strong downcurved setae or setulae on most of their 

 height. 



fascia. A transverse band on the dorsum of thorax or abdomen. 



frons. The anterodorsal region of the head bounded by the eyes laterally and 

 extending from the ocellar triangle to the lunula; the interfrontal area and the 

 parafrontals collectively. 



Typically the frons is well developed in both sexes, though usually narrower 

 in the male than the female, but is strongly reduced in some forms in which the 

 head is holoptic or almost so (e.g. in males of many Formosia, Ormiini and 



