194 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 12$ 



Length of head capsule i.i times its width. Width of thorax 1.5 times 

 that of head. First 4 abdominal segments about equal in width to 

 thorax; segments 5-7 about 1.3 times width of segments 1-4; expan- 

 sion of abdomen is gradual from anterior to posterior end, narrowing 

 rapidly at the eighth segment ; in profile, the larva appears the same 

 as others of the subgenus Dyarella. General color yellow to orange, 

 with dark patches at ventrolateral regions of abdominal segments 6 

 and 7. 



Head: Patterns on frons-clypeus and epicranial plates shown on 

 plate 40, figure 375. Each cephalic fan with 36 nonpectinate branches. 

 Mandible very long and narrow, with only i flat tooth on its inner 

 margin. Antenna 430 ^i long, pale yellow, 4-segmented, surpassing 

 the basal stalk of the cephalic fan ; segment 2>3>i ; segment 2 with 

 2 white patches ; in the middle of each appears a superficial indentation 

 giving the appearance of 3 distinct segments. Submentum with 9 

 apical teeth, the middle one larger than the others ; ventrolateral row 

 composed of 7 hairs in straight line, all appearing trifid or bifid at their 

 apices except the basal two which are simple ; lateral margins of sub- 

 mentum with 3 teeth in regular sequence. Occipital cleft widely 

 rounded (pi. 42, fig. 412). 



Thorax and Abdomen : Pseudopod (thoracic proleg) with 40-44 

 rows of hooks on its apex ; postclypeal sclerites well sclerotized and 

 pigmented, each near the posterior junction of the frons-clypeus with 

 an epicranial plate. Posterior sucker with 150-156 rows of hooks. 

 Anal gills with 3 main divisions that are bulbous and fleshy ; from each 

 lateral division there are 3 fingerlike projections, and from the middle 

 one, 4, giving a total of 10 branches in all. X-shaped sclerite with 

 anterior and posterior arms well sclerotized, the anterior arms broad 

 and somewhat expanded at their ends, with membrane along the an- 

 terior margin ; bulbous structure present on each side, between ante- 

 rior and posterior arm, bearing numerous spines; no rectal spines. 

 No ventral papillae or plaques on eighth segment. 



Types. — Series of 35 $$ (U.S.N.M. No. 191 11), collection of the 

 United States National Museum ; collected in Punta Gorda, British 

 Honduras. 



SIMULIUM (DYARELLA) RUBICUNDULUM Knab 



Simulium rubicundulum Knab, Insecutor Inscitiae Menstruus, vol. 2, No. 12, pp. 



177-179, 1914 (original description, female). 

 Simulium virgatum rubicundulum (Knab), Bequaert, in Strong, Sandground, 



Bequaert, and Ochoa, Contr. No. 6, Dept. Trop. Med. and Inst. Trop. Biol. 



and Med., Harvard Univ., pp. 215-216, 1934 (? and pupa). — Vargas, Rev. 



