BITING MIDGES WIRTH AND BLANTON 409 



radial cell; distal pale spot in cell R5 hourglass-shaped, oblique, 

 broadly meeting wing margin; apices of veins Mi and M2 with a small 

 pale spot at wing margin; cell Mi with two pale spots, the distal one 

 located far from wing margin; two distal pale spots in cell M2, the 

 apical one located at the wing margin; cell M4 with a round pale spot 

 almost meeting wing margin; only one small round pale spot in distal 

 part of anal cell; cell M2 with no pale spot lying in front of mediocu- 

 bital fork, a small pale spot present lying behind medial fork. Macro- 

 trichia sparse and in rows on distal fourth of wing in cells R5, Mi and 

 M2; costa extending to 0.61 (0.59-0.62, n=10) of distance to wing tip. 

 Halter pale. 



Abdomen. — Dull blackish. Spermathecae two, oval, slightly une- 

 qual, measuring 0.046 by 0.029 mm. and 0.040 by 0.026 mm., the 

 bases of the ducts sclerotized a short distance. 



Male genitalia: Ninth sternum with a moderately deep caudo- 

 median excavation; ninth tergum broad apically with long, extremely 

 slender, apicolateral processes. Basistyle with ventral root foot- 

 shaped, dorsal root short and slender; dististyle slender and markedly 

 curved to pointed tip. Aedeagus with broad, pointed basal arch 

 extending to two-thirds of total length, the basal arms slender and 

 curved; distal portion short and stout with bluntly rounded tip. Par- 

 ameres each with large basal knob, stem stout, markedly bent at mid- 

 portion, the part distad stout with a low, fiat, extensive, ventral lobe, 

 the apex narrowed to simple sharp point. 



Distribution: British Guiana; Honduras (Lancetilla) ; Panama; 

 Venezuela. 



Panama records: 

 BocAS DEL ToRO PROVINCE: Almirante. 



Canal Zone: Fort Sherman, Loma Boracho, Mojinga Swamp. 

 Panama Province: Isla Taboga. 



Discussion: Ortiz (1954) has described fernandezi from Venezuela, 

 a species very similar to fluvialis but differing mainly in having the 

 poststigmatic pale spots in cell R5 narrowly fused, lacking the pale 

 spot at wing margin at the apex of vein M2, having a pale spot present 

 in front of the mediocubital fork, having sensoria present on segments 

 III, vii-x and being slightly larger, wing 1.0 mm. long. 



61. Culicoides tetrathyris, new species 



Figure 64 



Female: Length of wing 0.85 (0.69-0.87, n=12) mm. 



Head. — Eyes nearly contiguous, bare. Antenna with flagellar 

 segments in proportion of 15:12:13:14:14:14:14:14:19:20:21:20:34, an- 

 tennal ratio 1.09 (1.04-1.14, n=4); distal sensory tufts present on 



