312 U. S. NATIONAL MUSEUM BULLETIN 216 



The genus Strongylopsis is close to Coccygomimus and possibly 

 represents only an aberrant group of species. We have seen three 

 species of Strongylopsis (the genotype and two undescribed species), 

 all from eastern Europe. They differ from typical Coccygomimus in 

 a more depressed, elongate form, wider and more convex face, and 

 wider, flatter clypeus. In some species the apical margin of the male 

 subgenital plate is weakly concave rather than prolonged. 



The species of Coccygomimus are divisible into more or less natural 

 groups, of which four occur in the Nearctic region. The main char- 

 acters for distinguishing the Nearctic species groups are in the widths 

 of the epipleura. It is probable that these groups, as defined, are 

 only partially natural, but they are nevertheless useful. The species 

 hesperus and stricklandi present the main difficulty in the practical 

 application of the groupings, as on the basis of epipleural characters 

 the males of these two would go in the sodalis group and the females 

 in the contemplator group. They are assigned, rather arbitrarily, to 

 the contemplator group. If these two species were eliminated it 

 would be practical to make a key to the Nearctic species following 

 relatively natural lines, but with their presence it has seemed better to 

 resort to an artificial key, as below. 



Some judgment and experience are needed in the interpretation of 

 the epipleural characters, as in individual specimens the epipleural 

 widths vary somewhat with the sex and size. Males tend to have all 

 epipleura narrower than females, and small specimens of both sexes 

 tend to have them narrower than larger specimens of the same sex 

 and species. 



Walkley (1958, U. S. Dep. Agr., Agr. Monogr., no. 2, 1st. suppl., 

 p. 38) has recorded the European Coccygominus turionellae (Linnaeus) 

 1758, as introduced into Canada and C. aethiops (Curtis) 1828, as 

 occurring in Greenland. According to a letter from her, the record 

 of C. aethiops is based on a published record by Lesse (1952, Bull. 

 Soc. Ent. France, vol. 57, p. 55). 



Lesse's specimen has been borrowed from the Paris museum and 

 found to be a small, abnormally dark-colored male of C. sodalis, so 

 aethiops can be removed from the list of Nearctic species. It has 

 not, so far, been possible to verify the establishment of C. turionellae 

 in Canada, but neither have we found reasons to consider the record 

 incorrect. This species is not included in the treatment below. 

 Specimens will key to C. sodalis, from which they differ in having 

 shorter and paler hairs, a premedian white band on the hind tibia, 

 and narrower epipleura on tergites 4 and 5. 



