20 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 123 



Chalcomorphina planes, new species 



Clearly congeneric with C. aurata Enderlein, the type and only 

 known species in the genus, but differing in a number of respects, 

 including the following: the vertex of the female is not elevated, 

 as in C. aurata; the antennae, and particularly the scape, are shorter; 

 the extent of the golden mesonotal pile of the female is much less 

 extensive; and the scutellum is much more nearly on a plane with 

 the mesonotum, with the apical part, particularly in the female, 

 much less robust. 



Female. — Entirely black except antennae, legs, wings, halteres, 

 and ovipositor. Head structurally similar to that of C. aurata but 

 longer, the frons narrower, occiput not so distinctly concave, vertex 

 and ocellar triangle not unusually elevated, face not projecting at 

 antennal bases, and proportions of antennae different. Comparative 

 ratios in holotype of C. planes and (in parentheses) a female O. aurata 

 from Peru: head length to head height 0.63 (0.52 excluding, 0.48 

 including, ocellar triangle) ; frons at narrowest and at vertex, respec- 

 tively, to head width 0.14, 0.19 (0.21, 0.25); antennal length to head 

 length 1.18 (1.66); scape to entire antenna 0.33 (0.48). Frontal callus 

 defined only by a narrow transverse impression, area above this com- 

 pletely shining, below with orbits extending to lower eye margin 

 densely yellow tomentose, leaving median part of lower frons shining, 

 middle of face, however, not shining and with scattered, appressed 

 whitish hairs; gena shining; occipital orbits not developed. Mesonotum 

 with golden tomentum as in C. aurata, but more limited in extent; 

 this tomentum forming a median longitudinal vitta, a narrow cross- 

 band just before the suture and another in front of scutellum and 

 extending from one supra-alar region to the other, also basal half 

 of scutellum golden tomentose; lateral presutural area shining, broadly 

 set with about eight irregular rows of appressed yellow hairs, these 

 merging into a small patch of tomentum medio-anteriorly, above 

 the humerus; rest of mesonotum opaque and with appressed black 

 hairs and tomentum. Pleura as in C. aurata, mostly bare and shining 

 above except a patch of appressed white hairs on niesopleura, below 

 mostly with white hairs. Scutellum at but a slight angle, not more 

 than 15°, with mesonotum (about 60° in C. aurata), structurally as 

 in C. aurata but not so robust. Legs wholly yellow. Halteres with 

 brownish-yellow stalk and whitish knob. Wing hyaline; venation as 

 in C. aurata and similar to that of Meristocera (fig. 15), but veins 

 except part of M separating basal cells mostly distinct, not mere 

 folds; cross- vein r-m either wanting or distinct and very short, the 

 same variability in this respect occurring in C. aurata; M 2+3 arising 

 distinctly beyond r-m; wing set with microtrichia except at extreme 

 base; alula more acute apically than in Meristocera, completely beset 



