REVISIONARY CLASSIFICATION OF RUTILIINI 25 
Genus FORMOSIA Guérin-Méneville 
Formosia Guérin-Méneville, 1843 : 263. Type-species: Rutilia mirabilis Guérin-Méneville 
1831, by monotypy. 
Dracnosis. Facial carina large, widening ventrally or with subparallel sides, at most only 
slightly widened medially. Epistome usually not strongly prominent. ¢ head holoptic or 
nearly so, eyes always strongly approximated, upper eye facets sometimes conspicuously en- 
larged and set off from small lower facets. Parafacials always bare. Buccal opening normal, 
if somewhat narrowed then conspicuously wider than facial carina. Genal dilation well 
developed, usually not reaching forward as far as front level of eye. Head often partly metallic. 
Arista pubescent or short-plumose. Palpi normal. Prosternum and prosternal membrane 
bare. Scutellum with apical setae at same level as, and not readily distinguishable from, other 
marginal setae; marginal setae stiff and straight, normally at least five pairs; disc of scutellum 
often markedly flattened. Postalar callus with 3-5 strong setae. Postalar wall with dense 
hair tuft. Suprasquamal ridge bare. Upper calypter normal. Tegula with normal long wiry 
posterior setulae. Costal base not explanate. Abdomen with stout spiniform setae directed 
downwards on ventral margins of tergites; T3 with median transverse row of spiniform marginal 
setae (except in males of most Euamphibolia spp.); intermediate tergites without discal setae. 
T5 short and broad, usually with well formed median depression and prominent posterior 
corners. 
DISTRIBUTION. From Java to Solomon Islands and Queensland, one species (see 
Euamphibolia) reaching to Tasmania and Western Australia; especially well repre- 
sented in Moluccas, New Guinea and Bismarck Archipelago. Unknown from 
Philippine Islands and possibly absent. 
Discussion. This is the predominant genus of Rutiliini in the Papuan subregion 
and contains many large and attractive species of beautifully patterned and metallic 
flies which often have a brilliant golden green to violet-blue coloration; the general 
appearance, both of shape and colour patterns, resembles that of many Rutilia 
species, and Formosia and Rutilia are without doubt very closely allied genera. 
Despite the superficial resemblance, Formosia is easily distinguished from Rutilia, 
and from all other genera of Rutiliini here recognized (except Formodexia gen.n.) by 
the presence of a thick tuft of long hair on the side wall of the postalar callus (Text- 
fig. 25). This is a remarkable and very unusual character which, to the best of my 
knowledge, does not occur elsewhere in the Tachinidae, and in the Rutiliini is 
confined to Formosia and Formodexia (though occasional specimens of Rutilodexia 
and Rutilia s.1. may have a very few hairs on the extreme upper edge of the postalar 
wall adjacent to the postalar rim). The features distinguishing Formosia from 
Formodexia are discussed under the latter genus, and a tabulation of the main 
differences between Formosia and Rutilia s.l. is given in the treatment of Rutilia. 
Six genera have been described in the Rutiliini which are here considered not to be 
generically distinguishable from Formosia. These are Pseudoformosia Brauer & 
Bergenstamm, Euamphibolia Townsend, Chromocharis Enderlein, Hega Enderlein, 
Laccura Enderlein and Pancala Enderlein. Two of these names, however, apply to 
rather well defined segregates within Formosia s.l. which it is thought useful to recog- 
nize as subgenera, as these subgenera (viz. Pseudoformosia and Euamphibolia) can 
be defined by quite constant structural features which are associated with rather 
conspicuous differences in general facies and pattern. The other four names (all 
