No. 7.- — The Ants of the Genus Opisthopsis Emery. 

 By William Morton Wheeler. 



contributions from the entomological laboratory of the 

 bussey institution, harvard university, no. 142. 



The species of the singular Camponotine genus Opisthopsis are 

 confined to the AustraHan and Papuan regions and are readily dis- 

 tinguished from other ants by their usually striking coloration and 

 very large and prominent eyes, situated at the posterior corners of the 

 head. The first, or type-species was described in 1864 by Frederick 

 Smith, under the name Formica (Myrmecopsis) respicitns from New 

 Guinea. As Guerin had given the name Myrmicopsis in 1830 to a 

 genus of Mutillidae Emery in 1893 saw fit to change that of the ant- 

 genus to Opisthopsis. This was hardly justified by the rules of nomen- 

 clature, because Smith's and Guerin 's names differed by a letter. 

 Forel, however, discovered that Myrmecopsis had been used by 

 Newman as early as 1850 for a genus of Lepidoptera, so that Emery's 

 name became valid. 



Our knowledge of the species of Opisthopsis has grown very slowly. 

 Up to the present time five species and a subspecies have been added 

 to the genus by Emery and Forel. The material on which these were 

 based seems to have been rather meager. Several of the described 

 forms were evidently known to Majr in 1876 but he regarded them 

 merely as color varieties of the typical respiciens. Emery and Forel,^ 

 however, believe that these color forms are relatively constant and 

 therefore regard them as distinct species. While in Australia during 

 the winter of 1914 to 1915 I collected a considerable number of Opis- 

 thopsis and have since received a series of specimens from the Museum 

 of South Australia and a species collected in the British Solomon 

 Islands by Dr. W. M. Mann. A study of this material, comprising, 

 in addition to all but one of the previously known forms, five unde- 

 scribed species and as many varieties, shows that the genus is very 

 homogeneous. The various forms differ from one another by slight 

 peculiarities in the structure of the head and thorax, sculpture and 

 pilosity, correlated with more conspicuous differences in coloration. 

 A consistent "lumper" would probably regard all the forms as merely 

 so many varieties or subspecies of a single variable species, but as 



