Carpenter et al.: Mosquitoes of Southern U. S. 33 



form of basal or apical bands or lateral patches, may be present on the tergites 

 of many species. Although the shape and extent of these markings may vary 

 somewhat on individuals within a species, they are nevertheless useful charac- 

 ters. Scale patterns are usually not so evident on the venter, but the pre- 

 dominating color of the scales may be important. 



The shape of the female abdomen may be of diagnostic significance. In 

 Aedes and Psorophora, for example, the abdomen is tapered apically, with the 

 8th segment withdrawn into the 7th. In the other genera occurring in the 

 southern United States, the abdomen does not taper appreciably, being 

 broadly truncate or bluntly rounded at the apex, although the 8th segment 

 may be partially withdrawn in some cases. 



MALE terminalia. — The terminal abdominal segments of the male mos- 

 quito are greatly modified for copulation, exhibiting variations in structure 

 which are of much taxonomic value. The term male terminalia is used here 

 to include the anal and genital structures of the 8th, 9th and 10th abdominal 

 segments. The terminology followed is essentially the same as that used by 

 Ross and Roberts (150) with slight modifications. 



The male terminalia of the Culicinae undergoes a rotation of 180 on 

 its longitudinal axis shortly after the adult emerges so that the structures 

 which were dorsal become ventral, and vice versa. In referring to structures 

 of the male terminalia, however, the original positions before rotation are used 

 even though they appear opposite on the mature specimen. 



The presence or absence of certain structures, as well as the modification 

 of these structures, comprises the taxonomic characters found in the male 

 terminalia. The structures include the eighth abdominal segment, ninth tergite, 

 ninth sternite, proctiger, phallosome and supporting structures, basistyles, disti- 

 styles, and claspettes (Figs. 12 to 14). They are considered separately as 

 follows : 



Eighth abdommal segment. — Although this segment is included in the male 

 terminalia, it is usually unmodified. It is relatively unimportant in Aedes, 

 Psorophora and most Ciilex, although it may bear diagnostic setae or spines 

 dorsally in some genera, particularly Mansonia and Wyeomyia. 



Ninth tergite (IX-T). — The ninth tergite and the lobes of the ninth 

 tergite borne postero-laterally or submedially on the transverse band of the 

 ninth tergite, often provide good characters. The extent of sclerotization and 

 the shape of the transverse band of the ninth tergite and the developmnt, 

 position, and armature of its lobes are particularly significant. 



Ninth sternite (IX-S). — The ninth sternite is usually unmodified in the 

 mosquitoes of the southern United States and unimportant in classification. 



Proctiger. — The proctiger, made up of elements of the tenth abdominal or 

 anal segment, varies considerably in the different genera of mosquitoes. The 

 tenth tergite is usually reduced. The tenth sternite (X-S) or paraproct is 

 usually the most strongly developed portion and fonns a pair of slender, 

 sclerotized supports for the anal membrane (A-M) in most genera, as in 



