466 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 109 



Abdomen. — Blackish. Spermathecae two (occasionally three, as 

 figured), slightly unequal, ovoid, measuring 0.043 by 0.038 mm. and 

 0.038 by 0.029 mm., the bases of the ducts not sclerotized. 



Male genitalia: Ninth sternum with a moderately deep caudo- 

 median excavation; ninth tergum with distinct caudomedian notch, 

 the apicolateral processes large and pointed. Basistyle with dorsal 

 root short and stout, ventral root about twice as long, appearing 

 extremely long and slender, dististyle stout at base, gradually tapered 

 to very slender, pointed, bent tip. Aedeagus very broad and stout; 

 basal arch extending to a third of total length; basal arms short and 

 stout with a distinct, lateral, bent hook, distal portion with very broad, 

 truncate tip. Parameres separate, each with a large, laterally directed 

 basal knob, stem slender on lateral basal portion, abruptly bent with 

 the straight longitudinal portion swollen basally, tapered to extremely 

 fine, simple, recurved tip. 



Distribution: — Aruba; Venezuela; Panama. 



Panama records: 



Canal Zone: Anc6n (May 18, 1914, S. T. Darling, outside house), Corozal 



(May 18, 1914, from ear of mule, S. T. Darling). 

 CocL^ Province: Puerto Aguadulce. 

 Herrera Province: Puerto Chitr6. 



Los Santos Province: Guarar4, LaPalma, LasTablas, Puerto Mensab4, Quemado. 

 Veraguas Province: Divisa. 



Discussion: C. arubae is not closely related to any other known 

 species. In general appearance, with its pepper-and-salt wing pattern 

 and broad, grayish brown mesonotum with pattern of punctiform 

 brown dots, as well as the presence of frontal tubercles, it greatly 

 resembles species of the nubeculosus group of the subgenus Mono- 

 culicoides Khalaf such as the North Am.enc&n variipennis (Coquillett), 

 but all those species have but one elongate spermatheca and the male 

 parameres fused. It is possible that arubae is a very primitive member 

 of this group. 



The stigmalis group 



This group consists of moderately large species with pruinose, 

 blackish mesonotum and bare, very poorly marked wing; second radial 

 cell very long and narrow, forming a blackish stigma; antenna with 

 sensoria present on segments iii, viii-x; four tibial spines; two sperma- 

 thecae; male genitalia with ventral root of basistyle foot-shaped; 

 apicolateral processes short; paramere with simple basal knob, stem 

 straight without ventral lobe, the apex fringed; aedeagus with high, 

 rounded basal arch and broad apex. 



Panama species: One: C. stigmalis Wirth. 



