REVISIONARY CLASSIFICATION OF RUTILIINI 27 
scutellum usually conspicuously flattened. Fore coxa almost completely haired on anterior 
surface. Transverse row of erect median marginal setae of T3 present in both sexes. T5 with- 
out strong setae behind the transverse row (a few exceptions). 
DISTRIBUTION. Occurring from Malaya and Java eastwards to the Solomon 
Islands, and known from Selangor, Java, Celebes, Molucca Islands (including Halma- 
hera, Ternate, Batjan, Morotai, Obi, Seram), New Guinea, Aru Islands, New Britain, 
New Ireland, Lavongai, Bougainville, and the major islands of the Solomons chain 
south-east to Guadalcanal. Unknown from Philippine Islands (possibly not 
represented there), absent from Australia. 
Discussion. Formosia s.str. is the largest subgenus in number of described 
species (and several additional undescribed species are known from the New Guinea 
area) and contains most of the brilliant metallic forms of Rutiliini that form such a 
characteristic element in the Tachinid fauna of the Papuan subregion. The sub- 
genus is easily distinguished by the extensively haired fore coxae, in which almost 
all of the anterior surface is haired (Text-fig. 16), an unusual feature found nowhere 
else in the Rutiliini; in other Rutiliines, as in most Tachinidae, the inner half of the 
anterior surface of each fore coxa is almost entirely bare (there being only a few hairs 
towards the tip). The one sternopleural seta and the one posterior intra-alar seta, 
together in correlation, also uniquely distinguish Formosia s.str. from the other 
subgenera. A rather unusual character, too, though occurring in some other Ruti- 
liini, is the slender tapering proboscis, and the strongly flattened scutellum of most 
forms is another feature exceptional among Rutiliini as a whole. 
Formosia s.str. is especially well represented in the lowland rain forests of New 
Guinea and the Bismarck islands, where some species are common at times, but a 
few species also occur in small patches of relict forest in the New Guinea highlands. 
Adult flies can often be found resting on low herbage, especially on the undersides 
of the leaves of wild ginger and similar plants, but nothing is yet known of the host 
relations (almost certainly, however, Scarabaeoid beetles are the hosts). 
Nearly all the species of Formosia s.str. form a rather homogeneous group having 
characters closely similar to those of the type-species, PF’. (F.) mirabilis, but a new 
species (described herein) from Guadalcanal, in the Solomon Islands, is rather dis- 
junct from the main body of species—although it fits Formosia s.str. well in all 
essential characters—and is here treated as a group of its own. The two groups 
recognized are keyed and defined below. 
KEY TO THE SPECIES-GROUPS OF FORMOSIA s:.str. 
1 Abdominal T5 with some long strong erect setae laterally behind the transverse row. 
Head entirely thickly pollinose, nowhere metallic. Surstyli of ¢ genitalia in 
profile strongly acuminate and ending in sharp point (Text-fig. 49), the whole 
surstylus somewhat hook-like : . viridiventris-group (p. 28) 
- Abdominal T5 without strong setae chine the transverse row of setae. Postorbits 
and genal dilations, sometimes also parafrontals and upper parafacials, metallic. 
Surstylus of § genitalia not of this form, always rounded at tip (Text-figs 41-44) 
mirabilis-group (p. 29) 
