56 COSTA RICAN DIPTERA 



Table of Costa Rican Species 



1. Face seen from above with stripes or series of silvery or white spots 2 



Face unicolorous 5 



2. Face shining black with, two silvery stripes; frons opaque, metallic colored 



with orbits and preocellar dash velvety black nana 



Face with three narrow stripes and orbits silvery; frons evenly shining or 



brownish 3 



Facial and frontal orbits silvery; mesofacial area yellowish and separated 



from orbits by a black stripe pulchra 



3. Opaque species 4 



Shining black species nitida 



4. Second costal section at least twice as long as third; large species (2.25 mm.). 



nepos 

 This section at most sUghtly longer than third; smaller species (1.7 mm.). 



trilineata 



5. Fore femora with short spines beneath; cheeks very broad aenea 



Femora without spines; cheeks narrow 6 



6. Opaque species with silver}^ orbits; abdomen velvet}^ black, with apex con- 



spicuously white or silvery; cheeks narrow leucoprocta 



Not so colored 7 



7. Face with secondary series of minute out-curved bristles; orbits broad and 



black, silvery setulosa 



Without secondary series of facial bristles; orbits pale obscurella 



Discocerina nana Williston 



1896. Discocerina 7iana'\\ iUiston, Trans. Ent. Soc. London, 1896, 396, (St. 

 Vincent). 



This pretty species, belonging to a group in which the orbits 

 are conspicuously silver^', is distinguished by the opaque, velvety 

 black frons contrasted with the two greenish or bluish stripes, 

 and the long narrow face with the median area shining black, 

 margined laterally with the narrow silvery orbits. The general 

 color is shining black, with antennae, halteres and tarsi pale. 



One specimen; Juan Viiias, April 28, 1910, (at brook near 

 woods). 



Discocerina pulchra new species 



Black; antennae except apices, palpi, knees, apices of tibiae, and tarsi except 

 apices, pale. Halteres white. Wings hyaUne with pale veins. 



Frons opaque, brownish with lower orbits silvery. Face opaque, yellowish 

 medianly with shining black, sublateral stripe and broad silvery orbits. Meso- 

 notum subopaque, olivaceous; pleura sparingly grajdsh. Abdomen shining 

 black. Face -with, uppermost pair of facial bristles approximate and cruciate, 

 next lower, up-curved mesally, also another series of three to four laterally up- 

 curved bristles. Length. — 1.5 mm. 



