16 U.S. NATIONAL MUSEUM BULLETIN 24 3 



The subfamilial and tribal keys are based upon fully mature specimens, 

 are worldwide in scope, and use only those structural features that apply 

 equally well to individuals of all species regardless of sex, brachyptery (pis. 

 1, 45) or machroptery (pi. 46), and distribution. As dichotomized herein, 

 the authors have embodied the higher categories formulated by Drake and 

 Davis in their basic treatment of the Tingidae. 



For the sake of uniformity in tingitaxonymy, the structures (figs. 1-6) 

 customarily used in the description of species, genera, and in the formation 

 of taxonomic keys are semidiagramatically figured with their respective 

 technical names affixed. Some nymphs (pis. 31, 33, 37) and many adults 

 (pis. 2, 43, 52, 54) are illustrated to depict clearly the habitus of represent- 

 ative forms found in various subfamilies and tribes. 



Key to Subfamilies of Tingidae 



Dorsal surface finely to coarsely punctate, never lacelike; compound eyes vestigial, 

 each with a small number of poorly developed, usually scattered ommatidia; 

 antenna with segment I shortest, II and III nearly equal, IV longest; pronotum 

 without discal carinae, each lateral margin above with a very narrow low 

 ridge; scutellum fairly large, triangular, exposed; ostiole and furcated ostiolar 

 canal unusually prominent, somewhat Y-shaped, the vertical sulcus furnished 

 with a backward projecting branch; evaporatorium enormously developed, 

 covering entire metapleuron, hind part of mesopleuron, and then extending 

 downward on the respective thoracic sterna to the laminar ridge of rostral 

 sulcus; abdominal sterna II through IV fused, other sterna free. Macrop- 

 terous form unknown. Myrmecetophiles (pis. 53, 54, 55, 56). 



Subfamily Vianaidinae Kormilev (p. 443) 



Dorsal surface finely to coarsely lacelike; compound eyes fully developed; each 

 with a large number of normal ommatidia; antenna with segment I slightly 

 to much longer than II, II usually shortest, sometimes I and II subequal, III 

 customarily longest, rarely III and IV subequal lengthwise, IV commonly 

 moderately long; pronotum rarely noncarinate (pi. 1), almost always carinate 

 with carinae present in combinations of one (pis. 4, 1 4), three (pis. 3, 5, 9), or five 

 (pi. 6); scutellum small, exposed (pi. 2) or concealed (pis. 10, 12, 13) beneath 

 hind margin or backward process of pronotum; ostiole and ostiolar canal 

 of each metapleuron either present or absent, when present (figs. \a, 3) 

 with a slightly arcuate, nonbranching, nearly vertical canal, without distinct 

 evaporatorium; abdominal sterna II and III fused, other sterna free. Pter- 

 ygopolymorphic forms found in many species 2 



Head always long, much produced in front of compound eyes, nearly porrect, 

 unarmed or armed with one to nine tubercular or spiniform processes; buc- 

 culae long, wide, straight, with anterior ends extending forward beyond apex 

 of clypeus, or shorter with ends curved inward and more or less meeting mesad 

 in front of labium; antenna with segments I and II always short, apex of 

 latter not reaching apex of clypeus; pronotum rarely noncarinate (pi. 1), 



