SPHAEROCERA IN CENTRAL AND SOUTH AMERICA — RICHARDS 225 



Gates Clarke and Mr. Curtis Sabrosky, 27 specimens were sent to 

 me. Careful study showed that 9 species were represented among a 

 random distribution of males and females. MaUoch first pointed 

 out that the reduced sternites of this group provide specific characters. 

 It seems that they provide by far the most important characters and 

 require careful study in every form. Unfortunately, the type of 

 reduction seems to be quite different in the two sexes, which are very 

 difficult to associate. In some species the structure of the pro- 

 sternum is a guide. The presence or absence of a minute antero ventral 

 spur on the hindtibia is less useful than MaUoch supposed because it 

 may vary in size and, in some species, is difficult to detect. The 

 nomenclature of the parts of the genitalia is the same as in Richards 

 (1961). The new species described below are compared with S. 

 ecuadoria, new species, rather than with S. bimaculata Williston 

 because only in the former is a long series of both sexes available. 

 Single specimens were examined of what appear to be six other species, 

 but their characters are largely minor deviations from those of the 

 species that are described. 



New Species AUied to Sphaerocera bimaculata Williston 

 Sphaerocera {Parasphaerocera) ecuadoria, new species 



Males and females. Black, dull, mesoscutum and pleuron only 

 slightly more shining; antennae brown; mentum and palpi testaceous; 

 legs pale yellow brown, tarsi and apices of femora slightly darker. 

 Abdomen with two large pale spots. Halteres yellow. Wings 

 h^^^line, venation brown. Length 2.5-3.0 mm. 



Lower face forming a flat trapeziform plate (fig. 7), coming up to 

 a point between the antennae; area of lunula also raised into a flat 

 triangular plate whose point meets that of the lower face at about the 

 lowest point of the antennal attachment; antennal foveae thus sharply 

 defined by a keel that is especially high internally and ventrally. 

 Buccae not striate except rather indistinctly posteriorly. Arista 

 four times as long as antenna with very short pubescence. Dorsum 

 of head very dull, no proper bristles. Prosternum (fig. 6) in the form 

 of a linear projection, about half as long as width of forecoxae, from 

 the triangular depression in front of the mesosternum. Mesoscutum 

 with some scaly tomentum and four indistinct rows of very short 

 bristles (corresponding approximately to dorsocentrals and acrosti- 

 chals), a few further, more lateral, bristles, irregularly placed. Scu- 

 tellum with a smaU denticle on each side, where the hindmargin curves 

 around to become transverse, doreal surface almost bare. Legs 

 thick, especially in the c^, d^ hindfemur twice as thick as midfemur. 

 Hindtibia with a small black anterior apical spur, shorter than one- 



