120 R. W. CROSSKEY 



three main humeral setae standing distinctly in a triangle, and the genal dilation 

 noticeably reduced; in addition to these characters the females possess a pair of 

 strong prevertical setae that are curved outwards over the inner margins of the 

 eyes, and the females of several forms (currently placed in Gynandromyia) have 

 the terminalia modified into a strongly sclerotized piercing ovipositor. No other 

 group of Goniinae seems to possess this combination of features. At least three 

 described genera come into this group, namely Gynandromyia Bezzi, Zenilliana 

 Curran and Phorocerosoma Townsend, but it is doubtful whether more than one 

 genus is justifiable. The first two of these genera have females with the piercing 

 type of ovipositor and have yellow palpi, and Verbeke (1962a) has - I think rightly - 

 placed Zenilliana as a synonym of Gynandromyia. But Verbeke maintains Phoro- 

 cerosoma and Gynandromyia as distinct genera, a course which is only very doubtfully 

 justified. In Verbeke's (1962& : 166) key to genera he uses the size of the ocellar 

 setae as the first characteristic which distinguishes Phorocerosoma (large ocellars) 

 from Gynandromyia (reduced ocellars) but this distinction is not even upheld by 

 examination of the holotypes of the respective type-species. During the present 

 work the holotypes of P. forte (= vicarium), type-species of Phorocerosoma, and 

 of G. seychellensis Bezzi, type-species of Gynandromyia, have been compared side 

 by side: comparison shows that ocellar setae are moderately well developed in 

 G. seychellensis and actually larger than the very fine reduced ocellar setae in P. 

 forte. From this and other specimens it is clear that these setae do not provide 

 a sound distinction between the two genera. 



Another chaetotactic character mentioned in Verbeke's key, the number of 

 ad setae on the mid tibia (two in Phorocerosoma, one in Gynandromyia) , also proves 

 unsatisfactory. Although it holds true for most specimens it is not exclusive, and 

 specimens of P. forte (including the holotype of its senior synonym, vicarium) 

 sometimes show only one ad seta on this tibia. The general strength of the chaetotaxy 

 is also unsatisfactory for generic separation: in P. postulans (Walker), which on its 

 whole facies and its female lacking a piercer is clearly a Phorocerosoma, the frontal 

 bristling is as strong as in Gynandromyia (indeed the whole female heads of postulans 

 and seychellensis are extremely alike). 



There appear to be no chaetotactic characters at all that will serve satisfactorily 

 to separate Phorocerosoma and Gynandromyia, and without such the distinction 

 between the genera is reduced simply to the form of the female terminalia and the 

 colour of the palpi (black-brown in Phorocerosoma, yellow in Gynandromyia). It 

 therefore appears that when properly revised the two genera will be merged, Phoro- 

 cerosoma sinking as a synonym. But until such a detailed revision is undertaken, 

 and pending more material of these little known flies, it is best to maintain Phoro- 

 cerosoma as a valid genus. 



Zenilliana pulchra Mesnil clearly associates in some way with the Phorocerosoma- 

 Gynandromyia complex, but this Oriental species (known only from the male holo- 

 type) cannot be reliably assigned to a genus at present. It has one ad seta on the 

 mid tibia (typically a Gyandromyia character) but has black-brown palpi (a Phoro- 

 cerosoma character), but differs from both these genera by having black occipital 

 setulae behind the post ocular row and by lacking median marginal setae on abdominal 



