REVISIONARY CLASSIFICATION OF RUTILIINI 15 
is widely separated from the vibrissal area (not reaching nearly as far forwards on 
the head as the front of the eye, Text-fig. 5). 
The eyes are well separated in both sexes in the majority of forms, but in Formosia 
_s.l. many species have the male head nearly holoptic. In these the upper part of the 

frons is almost obliterated, and the upper ends of the very attenuated parafrontals 
may meet in the mid line (obliterating the upper part of the interfrontal 
area completely). When the eyes are very nearly touching, the uppermost facets 
are usually very conspicuously enlarged, and the closeness of the male eyes and 
facet enlargement can provide useful specific characters. In all Rutiliini the eyes 
are totally bare. The eye-height in relation to the width of the gena will probably 
provide significant specific differences when sufficiently studied. The ocellar 
triangle is exceptionally prominent in forms with the male head virtually holoptic 
(a correlated feature). 
The form of the buccal opening provides a character of some taxonomic impor- 
tance. In most forms the opening at its narrowest (near the middle) is conspicuously 
wider than the facial carina, but in the genera Prodiaphania and Formodexia the 
buccal opening is unusually elongate and narrow (especially in the male) and at its 
narrowest point is not or scarcely wider than the facial carina (Text-fig. 15). The 
proboscis is of very uniform length, never greatly elongate, and the mentum has two 
moderately distinct shapes (Text-figs 12 & 13) which are constant in any genus-group 
segregate: in one shape the upper and lower edges of the mentum are subparallel 
seen in profile so that the mentum is not noticeably tapering, and in the other the 
upper and lower edges seen in profile distinctly converge apically so that the mentum 
is tapering. 
The antennae are always very small and their apices fall short of the epistomal 
margin by a distance about equal to, or only a little less than, their own length; they 
have no characters of supraspecific value, but the length of the third segment 
relative to the second sometimes provides a useful specific character. The palpi 
are minute (not longer than third antennal segment or basal thickness of the mentum) 
in Prodiaphania but are well developed, long and slender, in other forms (a little 
shorter than normal in Rutilia micropalpis and in Chrysopasta); they are sexually 
dimorphic in Chetogaster (slender in males, spatulate or clubbed in females) but not 
detectably so in other genera. 
THORAX, LEGS AND WINGS 
The structure of the thorax, legs and wings is extremely uniform and provides 
very few taxonomic characters. In a few species the posterior part of the noto- 
pleuron is produced as a knob-like swelling that is much more prominent than usual, 
but otherwise the thoraces are alike throughout the tribe. Some forms have slightly 
more elongate legs and tarsal claws than others, but not in any tangible way that 
can provide taxonomic characters. The tegula (epaulet) has a pair or more of long 
wiry setulae on its posterior edge in all Rutiliines except the one species of Formo- 
dexia. In some forms, especially species of subgenus Donovanius, the wing mem- 
brane is partially bare along some of the basal cells (at least no microtrichia visible 
by entomological microscope, although the S.E.M. microscope might prove them to 
