24 R. W. CROSSKEY 
spiniform setae. Those setae that are exceptionally thickened and spine-like and 
lack the even tapering from base to apex of typical setae. 
These occur commonly in Rutiliini and Tachinini and to a lesser extent elsewhere 
(e.g. some on the scutellum of Goniini). 
sternite 5. The deeply divided last visible abdominal sternite of the male 
(Text-fig. 20). 
sternites. The sclerotized plates of the mid venter of the abdomen (Text-fig. 20). 
The extent of exposure or concealment of the sternites by the ventral ends 
of the tergites can provide a useful taxonomic character. The sternites may 
be completely exposed in their surrounding membrane (as in many Phasiini) 
or completely concealed by overlapping of the tergites (as in Goniinae), and 
intermediate conditions occur in which the anterior sternites are mainly or 
fully concealed and the fifth sternite and part of the fourth exposed. Vestiture 
of the sternites is occasionally of minor taxonomic use. 
sternopleural setae. Setae standing on the wpper part of the sternopleuron 
(Text-fig. 7). 
The number and arrangement of these provide very valuable characters. 
Rarely they are totally absent or only one (posterior) one is present, but typically 
there are two or three (arranged I + I or 2+ 1). Four or (very rarely) more 
occur in some Goniinae and a few Tachininae and the arrangement of these 
may be significant (e.g. a characteristic group of genera of Sturmiini has the 
sternopleurals constantly arranged 2 + 2). When three are present the size of 
the lowermost seta in relation to the others may be useful. 
sternopleuron. The large lateroventral subtriangular area of the thorax between 
the fore and mid coxae and below the mesopleuron and pteropleuron (Text-fig. 7). 
Normally important only for its vestiture and this has very limited taxonomic 
use. A characteristic row of fine regular recumbent hairs in front of the mid 
coxa is present in Actia, and the ventralmost hairing may be modified into strong 
spiniform setae. 
subapical scutellar setae. The pair of setae inserted posterolaterally on the 
scutellar margin (Text-figs 5 & 6). 
These setae, together with the basals, are the most universally present setae 
on the scutellum and typically are the strongest pair. Their distance apart 
from each other at the base in relation to the distance between the insertion of 
one subapical seta and the basal seta of the same side of the scutellum provides 
an important character. Also important is the direction of the subapicals, 
e.g. whether diverging from each other as in Blondeliini or converging and 
crossing at their tips (enclosing the apical setae) as in Siphonini and Neaerini. 
sublunular bulla. A knob-like swelling between the antennal bases immediately 
below and continuous with the lunula. 
This occurs mainly in Phasiini, where in Alophora and allied genera the bulla 
is often polished and shining. 
supra-alar area. The outer edge of the scutum above the wing base. 
supra-alar setae. The outermost setae standing on the scutum (postsupraalar 
bristles of Townsend), other than the pre-alar seta (Text-fig. 4). 

