102 U.S. NATIONAL MUSEUM BULLETIN 244 



of broad, irregularly shaped sclerotizations present on eighth seg- 

 ment. Internal genitalia with bursa several times larger than sper- 

 matheca; ductus seminalis extremely long, convoluted; spermatheca 

 normal; accessory glands variously bilobed, arising posterior to 

 vestibulum; vestibulum frequently bilobed. 



Discussion. — This genus presents the greatest difficulty in species 

 delimitation of all the New World genera, largely because of the 

 paucity of reared and associated material representing the immature 

 stages as well as the adults. The lack of reliable, morphological 

 specific characters and the variation expressed in color and size have 

 added greatly to the problem. So little field work has been accom- 

 plished in this complicated group that any assumptions on probable 

 patterns of speciation and evolution would have to be based on slight 

 and probably misleading evidence. The principal areas of uncer- 

 tainty involve the forms of the West Indies and especially of Mexico. 



Key to the Species of Olketicus 



la. Tarsus of foreleg (figs. 184, 186) exceeding tibia in length; epiphysis approx- 

 imately % length of tibia and extending to, or surpassing, apex of that 

 segment; primaries either unicolorous or semitransparent (subgenus 

 Paraoikeiicus). 

 2a. Wings devoid of scales, semitransparent; medius undivided within cell of 



secondaries 45. O. zihiiatanejensis 



2b. Wings usually evenly scaled, rarely semitransparent; base of medius con- 

 sistently forked in both wings. 

 3a. Antennal pectinations gradually decreasing in length to apex (fig. 384). 



4a. Larval case smoothly cylindrical (fig. 94) 43. O. borsanii 



4b. Larval case elliptical in outline (figs. 92, 93), usually covered with few 



scattered fragments of plant material 42. O. bergii 



3b. Antennal pectinations diminishing in length before apex with outer 



fourth of shaft bisserate (fig. 385) 44. O. geyeri 



lb. Tarsus of foreleg (fig. 185) distinctly less than tibia in length; epiphysis usu- 

 ally less than % length of tibia and never extending to distal end of that 

 segment; primaries usually with distinct color pattern (fig. 58), but some- 

 times with wings semitransparent (subgenus Oiketicus). 

 5a. Wings semitransparent with usually no color pattern detectable. 



6a. Larval case with relatively few, scattered twigs arranged longitudinally 

 along case (fig. 98); adult with termen of secondaries only slightly 



sinuate 46. O. toiimeyi 



6b. Larval case with exterior covered by heavy thatching of short twigs 

 arranged in circular fashion around bag (fig. 100); secondaries with 



termen strongly sinuate to excavate 47. O. assimilis 



5b. Wings more heavily scaled with characteristic pattern easily observable. 



7a. Foretibia without epiphysis 52. O. platensis 



7b. Foretibia with epiphysis. 



8a. Wings of pale pattern, thinly scaled with outer areas normally appear- 

 ing rather translucent; relatively broad wing (fig. 49); wing expanse 

 44-53 mm 48. O. specter 



