336 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 109 



Wing.— Pattern as figured; pale spot over r-m crossvein small, but 

 broadly attaining costal wing margin; poststigmatic pale spot in cell 

 R5 extending slightly caudad behind second radial cell, distal pale 

 spot in cell R5 rounded, not meeting wing margin; vein Mi with a 

 small pale spot straddling it near its base, sometimes this spot con- 

 sisting only of the anterior portion lying in front of vein Mi; cells 

 Ml and M2 each with one distal pale spot, that in cell Mi not reaching 

 wing margin, that in cell Mg located at wing margin; pale spot in 

 cell M4 rounded, not following vein M3+4; one pale spot in apex of 

 anal cell; pale spot present straddling middle of vein M2; pale area 

 in base of cell M2 forming pale spots behind medial fork and in front 

 of mediocubital fork. Macrotrichia long and dense, extending nearly 

 but not quite to base of wing in cell M2 and anal cell; costa extending 

 to 0.55 (0.53-0.56, n=10) of distance to wing tip. Halter pale. 



Abdomen.— Brownish. Spermathecae two, very unequal, retort- 

 shaped, measuring 0.048 by 0.046 mm. and 0.035 by 0.028 mm., the 

 bases of the ducts sclerotized a considerable distance. 



Male genitalia: Ninth sternum with a very broad, shallow, caudo- 

 median excavation; ninth tergum long and tapering with very long, 

 stout, slightly flaring, apicolateral processes. Basistyle with ventral 

 root very slender, simple, dorsal root short and stout; dististyle short 

 with stout base and hooked tip. Aedeagus stocky, with basal arch 

 extending only to a fourth of total length of aedeagus, basal arms 

 nearly straight; distal portion more or less in form of a truncated cone 

 with broad apex. Parameres small, slender; each with a large, 

 laterally directed, basal knob, base of straight portion of stem bulb- 

 ously swollen, stem gradually narrowed to filiform, simple, ventrally 

 bent tip. 



Distribution: Panama; Guatemala; Mexico. 



Panama records: 



Canal Zone: Barro Colorado Island (type locality). 



CHiRiQuf Province: Volcdn. 



CocLii Province: El Valle. 



Los Santos Province: La Palma. 



Discussion: The reduced mandibles, remarkably enlarged third 

 palpal segment with very deep pit and small pore, and retort-shaped 

 spermathecae are distinctive features of this species. Culicoides 

 copiosus Root and Hoffman from Mexico closely resembles panamensis, 

 but has the distal pale spot in cell Mi extending to the wing margin. 



