N0 - 3622 STRATIOMYIDAE — JAMES 15 



type of C. pallipes indicates other outstanding differences, for example, 

 the much less strongly margined scutellum and the wholly reddish 

 yellow flagellum. On the basis of the rounded scutellum, P. callosa 

 traces to Lasiodeictes niger Lindner except for the black scutellar 

 vestiture of that species. 



Lindner keys three Psephiocera species with wholly yellow legs. 

 P. marginata and P. callosa differ from all of these, according to the 

 descriptions, in scutellar structure. The callosity on the antennal 

 flagellum of P. callosa is apparently unique in this genus, so far as 

 the known species are concerned. Comparison of P. marginata and 

 P. callosa with P. flavipes Enderlein, the type of the genus, shows a 

 number of differences; for example, the pleura of P. flavipes are 

 almost wholly bare and shining and the weaker wing veins are re- 

 duced almost to folds, as in Meristocera laticornis. Psephiocera metzi 

 Johnson from Jamaica, another yellow-legged species that is not 

 included in Lindner's key, is described as having three stripes of 

 yellowish-white tomentum on the mesonotum; in P. callosa and 

 P. marginata the mesonotum certainly is not striped. 



The value of the origin of R2-1-3 from the radial sector should be 

 discounted as a generic character. It can often be used to good advan- 

 tage, but there are a number of situations in which it can not be used. 

 These include cases in which the radial sector bows gradually after 

 its origin from vein R (cf. fig. 15) in contrast to those in which the 

 sector is bent abruptly at cross- vein r-m (cf. fig. 16). In the former 

 group, R 2+3 is often weak or even evanescent, so that its origin may 

 be indeterminable; even when it is determinable, it may be variable. 

 Considerable study needs to be made of venational characters in the 

 Pachygaster-like Pachygastrinae. 



Meristocera laticornis, new species 



Figures 14, 15 



The genus Meristocera Lindner was based on a single species, M. 

 aurea Lindner, from Santa Catarina, Brazil. The Dominica species is 

 very similar, according to Lindner's description, but can be distinguished 

 readily by the structure of the antenna, the flagellum in M. laticornis 

 being much broader and more distinctly triangular. 



Female. — Black, with antennae except above, proboscis, legs 

 including coxae, halteres, heavier wing veins, and cerci bright yellow. 

 Frons about 0.25 head width and parallel sided above callus (described 

 as one-third head width and narrowing above in M. aurea) ; vestiture 

 as described for M. aurea. Flagellum blackish above, the sensoria 

 large, prominent in the darkened area because of their contrasting 

 yellow coloration; pedicel on inner side extending strongly into 

 flagellum as in M. aurea. Vesture of thorax as described for M. aurea. 



