ART. 25. NEW SPECIES OF COSTA KICAN FLIES ALEXANDER. 7 



brown, the terminal third yellow; terminal flagellar segments uni- 

 formly dark brown. Front and anterior part of vertex cream-yel- 

 low ; remainder of dorsum of head brown. 



Mesonotal praescutum pale brown, the usual stripes darker brown 

 but indicated only near the suture, the median stripe bifid at anterior 

 end; scutum testaceous, the lobes dark brown; scutellum testaceous; 

 postnotum brown. Pleura brownish testaceous; a brown area on 

 mesepisternum ; mesosternum inf uscated. Halteres brownish yellow, 

 the knobs dark brown. Legs with the coxae and trochanters testace- 

 ous; remainder of legs brown, the femora paler basally. Wings 

 with a brown tinge, variegated with yellow, dark brown and yel- 

 lowish subhyaline ; costal margin light yellow with four alternating 

 blotches of dark brown, these including cells C and Sc^ fading out 

 posteriorly in cell R; the first brown area lies immediately beyond 

 the level of the arculus; the third at origin of i?s, the second mid- 

 distance between these last two; the fourth area occupies the end 

 of cell Sc^ confluent with the stigma ; the yellow spaces between these 

 brown areas are subcircular in outline ; a conspicuous yellowish 

 subhyaline area beyond the stigma in cells R^, and R^\ a yellowish 

 subhyaline area in the end of cell 1/, indistinctly connected with the 

 last yellow costal area ; the space behind vein Cu yellow ; indistinct 

 infuscations at base, midlength and apex of this yellow cubital area ; 

 the subhyaline areas elsewhere on wing-surface are very small, most 

 evident in the ends of the posterior and 1st Anal cells; veins dark 

 brown ; no macrotrichiae in cells of wing. Venation : Sc^ atrophied, 

 Sc^ ending before the fork of the long, straight Rs; tip of /?, ^^- 

 rophied ; petiole of cell M^ longer than m; m-cu obliterated. 



Abdomen brown, the basal tergites yellowish, the caudal margins 

 of the tergites narrowly paler brown. Ovipositor with the valves 

 horn-colored. 



Habitat. — Costa Rica. 



Holotype. — Female, Atirro, October 24, 1920 (A. Alfaro). 



Type.— C2it. No. 24699, U.S.N.M. 



Microti'pula costaricensis differs notably from the only other de- 

 scribed species of the subgenus, M. (M.) amazonica Alexander (Bra- 

 zil-British Guiana), in the coloration of the body and wings. In its 

 general appearance it agrees more closely with the subgenus Eumi- 

 crotipula Alexander in which the cells of the wing are densely pro- 

 vided with macrotrichiae. 



