4 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 123 



H. S. Dybas, Chicago Natural History Museum, who lent a great 

 number of Neotropical Triplacinae. 



Systematic treatment. — Neotropical Triplax species display a 

 wide range of coloration and moderate intraspecific variation in this 

 coloration. Coloration includes black, ferrugineous, piceous, fulvus, 

 yellowish brown, yellow, orange red, and red. Their general shape 

 ranges from elongate-elliptical to relatively oval; the body length to 

 width ratio ranges from about 1.6:1 to about 1.95:1. Specimens 

 studied ranged in length from 2.34 to 5.12 mm and in width from 1.28 

 to 2.81 mm. 



The head is elongate-oval, fitting tightly in the prothorax, and is 

 visible from above. The eyes are finely faceted. The antennae are 

 1 1-segmented, generally more than one-half the width of the pronotal 

 base; the club is relatively lax, its length 2 or more times its width. 

 Antennal segmental coloration varies within some species. The 

 terminal segments of the maxillary palpi are moderately to extremely 

 widened, their width ranging from about 2.75 to 4 or 5 times their 

 length; the maxillary palpus has a distinct brush present along the 

 truncate apex. The terminal segments of the labial palpi are short- 

 setigerous, each armed with a brush along its truncate apex. The 

 mentum varies from small and obscurely pentagonal to larger and 

 more distinctly pentagonal, with considerable intraspecific variation. 

 The postmandibular lobes range in development from moderate to 

 strong; in some species they are of diagnostic value, in others they 

 are not. 



The pronotum is margined laterally and basally, but it is 

 immarginate medioapically between the eyes. Its shape ranges from 

 subquadrate to subtrapezoidal. The pronotal angle pores are 

 distinctly umbilicate, of moderate to large size. 



The elytral striae are in some species strongly impressed, in others 

 they are not. The elytra are basally margined or immarginate. 



The prosternal lines are generally absent but when rarely present 

 they are short, straight, not exceeding extreme anterior edges of coxae. 

 The prosternum, with various degrees of punctuation among the 

 species, is subtrapezoidal in shape. Prosternal, pronotal epipleural, 

 mesosternal, metepisternal, and metepimeral sclerites, among others, 

 are distinct. Metasternal coxal lines are generally absent but 

 occasionally they are short, vestigial. 



The abdomen is composed of five sternites, the first being the widest. 

 This basal sternite has a narrow intercoxal process (not nearly so 

 broad as in the closely related genus Tritoma Fabricius). The 

 abdominal coxal lines are usually present. 



The anterior and middle coxae are globular; those of the hindlegs 

 are transverse. In comparison to the closely related genus Tritoma, 



