308 PROCEEDINGS OF THE NATIONAL MUSEUM vol. io9 



1.3-2.1), sensoria present on segments iii-xv or iii, viii-xv, and 

 only four tibial spines. 



This group is intermediate between typical Culicoides (Culicoides) 

 and the daedalus group of the subgenus Culicoides (Oecacta). Culi- 

 coides decor (Williston), known only from the island of St. Vincent in 

 the West Indies, belongs to this group (see remarks under nigrigenus). 

 There are three Panama species — chrysonotus Wirth and Blanton, 

 lutealaris Wirth and Blanton, and nigrigenus Wirth and Blanton. 



17. Culicoides nigrigenus Wirth and Blanton 



Figure 20 



Culicoides nigrigenus Wirth and Blanton, 1956, Proc. Ent. Soc. Washington, 

 vol 58, p. 222 (male, female; Panama; fig. wing, palpus, spermathecae, 

 male genitalia). 



Female: Length of wing 1.11 (1.02-1.25, n=8) mm. 



Head. — Eyes bare, contiguous. Antenna with flagellar segments in 

 proportion of 20:15:15:15:15:15:15:15:47:50:50:50:55, antennal 

 ratio 2.0; distal sensory tufts present on segments iii-x v. Palpal seg- 

 ments in proportion of 10 :20 :30 : 10 : 10, third segment greatly swollen, 

 1.9 (1.7-2.1, n= 6) times as long as greatest breadth, with a broad, deep 

 sensory pit. Mandible with 13 (10-15, n=10) teeth. 



Thorax. — Mesonotum yellowish brown, with grayish pruinosity 

 becoming very prominent in some specimens, anterior margin narrowly 

 dark brown, dark brown spot present just anterior to scutellum. 

 Scutellum concolorous with mesonotum, postscutellum and pleuron 

 dark brown. Legs yellow, fore and mid femora pale brown on basal 

 halves, hind femur with broad median brown band and distal two- 

 thirds of fore tibia brownish; prominent knee spot on all legs and 

 the narrow apex of hind tibia blackish; hind tibial comb with four 

 spines, the one nearest the spur longest. 



Wing. — Pattern as figured, with pale markings predominant, the 

 dark markings rarely extensive enough on distal half of wing to be 

 interconnected. Macro trichia very numerous on distal half of wing 

 and extending to near base in anal cell and cell M2; costa extending 

 to 0.64 of distance to wing tip. Halter yellowish white. 



Abdomen. — Brownish, the terga whitish. Spermathecae two, 

 pyriform, subequal, each measuring 0.057 by 0.044 mm. 



Male genitalia: Ninth sternum narrow, with a broad, shallow, 

 caudomedian excavation; ninth tergum with large, triangular, api- 

 colateral processes, the caudal margin between them truncated, with 

 a slight mesal notch. Basistyle with ventral and dorsal roots small 

 and simple, no spinose setae on mesal surface. Aedeagus V-shaped, 

 without anterior transverse marginal band or distal peglike internal 

 sclerotization, apex slender and rounded but not spherical. Para- 



