60 R. W. CROSSKEY 



semenovi Portschinsky from Mongolia) has not been seen, but it seems certain 

 that Zamimus must be very close to Tachinoestrus to judge from Portschinsky's 

 description: the resemblance in the remarkable heads is shown very clearly by 

 comparing the female facial views figured in the respective original descriptions 

 (Portschinsky, 1887 : pi. VI, fig. 7a for Tachinoestrus and Malloch, 1932ft : fig. 5 

 for Zamimus). The general appearance of Z. pendleburyi holotype is also remark- 

 ably similar to Portschinsky's coloured illustration of T. semenovi. It is possible 

 that the two type-species are congeneric, and that Zamimus could prove to be a 

 synonym of Tachinoestrus. Unfortunately with such rare insects it is difficult 

 to decide upon generic limits and synonymies in the absence of good data on 

 variability; probably many features in such aberrant forms, especially in the 

 chaetotaxy, are intraspecifically variable. 



Concerning Xanthooestrus I am not fully certain that Mesnil's synonymy with 

 Tachinoestrus is justified at this stage, and I prefer to accept Xanthooestrus as 

 valid for present purposes. I have not, however, seen specimens of its type-species 

 (X. fastuosus) and am perforce judging the characters of Xanthooestrus from a 

 specimen of X. formosus Townsend (which Townsend, 1938 : 269 says may not be 

 congeneric with fastuosus). It is evident, though, from Villeneuve's (1914) des- 

 cription (based on the male) that the true Xanthooestrus must be closely related 

 to Zamimus and it is not impossible that the latter genus is merely the female of 

 the former. Future revisionary work with adequate material might reveal that 

 the entire Tachinoestrus-Xanthooestrus- Zamimus complex should be treated as 

 one genus. 



The foregoing discussion has concentrated upon forms that, if they are Palposto- 

 matini at all, are very strongly apomorphic. At the other end of the scale is the 

 genus Parhamaxia Mesnil, which - although Palaearctic - has been examined 

 during the present work. This genus has a quite normal tachinid appearance 

 with strong chaetotaxy in which both pra seta and second sa seta are present and 

 in which strong median discal setae are present on the intermediate abdominal 

 segments. It has an obvious resemblance, especially in head profile, to Hamaxia 

 (=Palpostoma) and appears without doubt to be a plesiomorphic palpostomatine. 

 Hence the Palpostomatini appear to include a diversity of forms with very different 

 facies at the extremes but interlinked by Palpostoma itself, Parhamaxia representing 

 the plesiomorphic state and Eutrixopsis-Zamimus-Xanthooestrus the apomorphic 

 state. The discovery of the hosts of the two last-named genera would be of great 

 interest in determining the affinities more precisely, for if the association with 

 palpostomatines is correct then coleopterous hosts are to be expected (whereas 

 orthopterous hosts are to be expected if their affinities lie closely with the ormiines). 



Finally in this section it is desirable to mention the Australian Palpostoma 

 complex. Hardy (1938) treated Eustacomyia Malloch and Apaipostoma Malloch 

 as synonyms of Palpostoma and comprehensive revision of the tribe might prove 

 this course justified. However, as pointed out earlier (Crosskey, 1973ft), both 

 Eustacomyia (two species) and Apaipostoma (one species) are still known only from 

 the types of their included species, and it appears preferable to maintain these 

 genera as valid for the time being rather than to extend the definition of Palpostoma 



