NO. 3568 MELANOTUS — QUATE AND THOMPSON 3 



few species with which to contend, so identification of that Melanotus 

 fauna is not difficult. The bulk of the Melanotus are in the eastern 

 half of the United States, and this is where the greatest problems of 

 identification mil be encountered. 



It appears that nearly all American species of Melanotus north of 

 Mexico are now known. Supporting this conclusion is the fact that 

 of the 46 Nearctic Melanotus only nine (20 percent) are named in 

 this paper or have been named in the last few years, and half of these 

 have been recognized for at least 20 years. What few species may 

 remain undiscovered are probably in the Southwest. 



We have made an artificial division of Melanotus into three groups. 

 The first two, containing nearly aU the species, are based on the 



Figure 1. — Distribution of Melanotus in the United States (figures indicate the number 

 of species recorded in each state or area). 



presence or absence of mandibular pits. This is an obvious character 

 and it simplifies identification; however, we do not feel that this 

 single character indicates natural units, and the taxa based on it are 

 merely utilitarian. The third group, composed of only cribricollis 

 and chiricahuae, is characterized by large pronotal punctures and 

 reduced parameres in the male genitalia; it is probably monophyletic. 

 A key has been prepared which will simplify identification of most 

 specimens. The greatest difficulty wiU be indi^ddual variants that 

 do not seem to quite fit either part of a couplet. Many revisions have 

 failed to eliminate aU deficiencies, but for the majority of specimens 

 the key should provide a satisfactory shortcut to their proper 

 identification. 



