TACHINIDAE OF ORIENTAL REGION 81 



(Mesnil, 1973ft : 1211) that the germariochaetines are closely allied to Bigonicheta 

 Rondani (now a synonym of Triarthria Stephens) and its relatives that comprise 

 Mesnil's group Digonochaetina. This may be correct, but the adult morphology 

 of germariochaetines is so extraordinary that it does not offer particular support 

 for such a placement. The group might equally well be phyletically closer to 

 Minthoini as the fore tarsi (with their very reduced claws) are reminiscent of some 

 minthoine forms. 



The general appearance of the germariochaetine adult body is well shown in 

 Villeneuve's (1937a) figure of Germariochaeta clavata, but the figure does not convey 

 the sculpturing of the thoracic surface that is one of the most outstanding charac- 

 teristics in the group. In all Germariochaetini there is not only an exceptional 

 degree of reduction in thoracic chaetotaxy but there is also a curious (and in Tachi- 

 nidae exceptionally rare) development of microrugose sculpturing of the entire 

 thoracic surface - which gives the thorax very much the appearance of that in 

 many Hymenoptera or in brachycerous Diptera such as some of the Stratiomyidae. 

 An interesting point of resemblance with stratiomyids occurs with Lophosiosoma 

 bicornis Mesnil: in this species the scutellum has a pair of prong-like processes arising 

 from the posterolateral corners (Text-fig. 73), very much like those found in several 

 stratiomyid genera (prong-like tubercles on the scutellum are of extreme rarity 

 in the Tachinidae and I can recall no other tachinid that has processes like those 

 of L. bicornis). 



L. bicornis is specially interesting not only on account of this scutellar feature 

 but also because (unlike nearly all other Tachinidae) the hypopleuron is totally 

 bare and there is only one seta on the notopleuron. It also has a quite remarkable 

 superficial likeness to a winged ant, the abdomen (which as in all Germariochaetini 

 completely lacks strong setae) at first glance being much like the ant gaster. 



Although what is obviously apomorphic reduction of the chaetotaxy reaches its 

 most extreme form among germariochaetines in L. bicornis (which not only lacks 

 hypopleurals but also lacks sternopleurals, pteropleural, and the prostigmatic 

 seta, and has the mesopleural 'row' reduced to one seta) all the other species show 

 a strong degree of bristle loss. Most have no sternopleural seta and only one pair 

 of scutellars, the mesopleurals are usually only two, and the hypopleurals, ptero- 

 pleural and prostigmatic seta tend to be weak if represented. A definite trend is 

 shown by different species towards total sclerotized closure of the posteroventral 

 declivity of the thorax which seems to be correlated with reduction of the bristling. 

 In L. bicornis closure of the lower metathorax is complete (the metacoxae and 

 abdominal base being separated by a deep transversely complete sclerotic bridge) 

 and thoracic chaetotaxy reaches its most reduced state, whereas in L. javanum 

 there is virtually no closure (the median area being broadly membranous) and the 

 chaetotaxy is more complete than in other species - there being a seta on the sterno- 

 pleuron, an inner seta on the humeral callus in addition to the main outer one, and a 

 second pair of scutellar setae. Intermediate forms exist in which the posteroventral 

 declivity of the thorax is very largely sclerotized but there remains a very narrow 

 membranous median suture (as in L. obliteratum) . Both L. javanum and L. oblitera- 

 tum are new species (described below after the keys) that show a form of semi- 



