TACHINIDAE OF ORIENTAL REGION 59 



am not making a designation at this time: it is better left pending until some worker 

 can undertake the general revision of the genus. 



The characters of P. aldrichi are of special interest in relation to the Oriental 

 palpostomatine genus Eutrixopsis Townsend, which in an earlier paper (Crosskey, 

 1973&) I suggested was possibly not a true palpostomatine. Apart from possessing 

 three pairs of marginal scutellar setae instead of two, Eutrixopsis differs from most 

 Palpostoma species by having the head holoptic in both sexes, the vibrissae obsoles- 

 cent, the epistome narrowed and flattened and much elongated in its dorsoventral 

 axis, and in possessing only one post ia seta. But P. aldrichi has a combination 

 of characters that give it a facies rather apart from other species of Palpostoma 

 and tending towards those giving rise to the characteristic facies of Eutrixopsis; 

 for example, it has one post ia seta, vibrissae smaller than usual, some narrowing 

 and elongation of the epistome, non-prominent vibrissal angles, and the head 

 nearly holoptic in both sexes (in other Palpostoma species the frons, of the female 

 at least, is distinctly developed and wider than that of the male). The occurrence 

 of these Eutrixopsis-like features in a species that on total suite of characters 

 should be placed in Palpostoma suggests that Eutrixopsis is an apomorphic derivative 

 of Palpostoma-like forms, and Eutrixopsis is therefore accepted here as being a 

 true palpostomatine. 



Also here placed in the Palpostomatini, but with much less certainty that the 

 assignments are correct, are the aberrant genera Xanthooestrus Villeneuve and 

 Zamimus Malloch - which appear certainly closely related to each other, whatever 

 their general affinities may be. Both these genera are extremely difficult to place 

 satisfactorily because of the strongly apomorphic modifications of the head, and 

 because the host relations and early stages remain unknown; furthermore, even the 

 adult flies are very rare in collections, and Zamimus is known only from the female 

 holotype of the type-species. The heads have the oral cavity and proboscis 

 exceptionally reduced and the lower anterior part of the head concomitantly 

 modified into paired broad flattened subfacials flanking a reduced or even linear 

 dorsoventrally elongate epistome; associated with these modifications (which appear 

 to represent a yet more extreme development from the Eutrixopsis head form) 

 the antennae are extremely small, again much as in Eutrixopsis. The general 

 appearance of the highly apomorphic heads in Xanthooestrus and Zamimus is 

 strikingly similar to that of some Ormiini such as Therobia and Aulacephala, and 

 Townsend (Manual of Myiology) placed both Xanthooestrus and Zamimus in his 

 tribe Aulacephalini (i.e. part of the tribe now known as Ormiini). However, the 

 two genera differ from the Ormiini in having a normal non-inflated prosternum 

 and in having the bend of vein M widely obtuse, and usually gently curving without 

 an appendix, and it is preferred to regard Xanthooestrus and Zamimus as extreme 

 developments from a Eutrixopsis-like ancestor: they are therefore placed here in the 

 Palpostomatini as a. provisional measure until their affinities can be better determined. 



It is necessary to comment here on the Palaearctic genus Tachinoestrus Port- 

 schinsky, firstly because of the seemingly very close relationship between it and 

 Zamimus, and secondly because Mesnil (1973ft : 1228) has recently synonymized 

 Xanthooestrus and Tachinoestrus. The type-species of Tachinoestrus (namely 



