44 
VIII. Genus PTERONUS Jurine. 
Jurine, Nouvelle Méthode de Classer les Hyménopteres et Dipteres, T. 1, p. 61. 
Konow, Deutsche entomoloyische Zeitschrift, xxx1v, 1890, Heft 11, p. 237. 
Body large, hard; clypeus incised at tip; claws bifid; antennx long, frequently 
pale beneath; stigma usually unicolorous; mesonotum and mesopleure usually not 
or sparsely punctured; head subrotund; labium not or slightly prominent; eighth 
dorsal abdominal segment of male subtriangular, produced at apex; procidentia 
truncate at apex; hypopygium narrow at apex and subtruncately rounded; sheath 
of female small, narrow; apex never acuminate. 
The genus as characterized above by Konow is perhaps the largest in 
point of number of species of the several genera erected from the old 
genus Nematus. It is closely allied to the genus following it, but differs 
notably in the characters of the head and wings and in the general 
appearance. The males of the smaller species are not so readily sepa- 
rated from the males of Pontania. The genus has its type species in 
Pteronus myosotidis Fab., the only species remaining of those originally 
assigned to it by Jurine. The life-history of a few of the American 
species is familiar, as, for instance, that of Pteronus ventralis Say (the 
willow sawfly) and P. ribesii Scop. (the gooseberry sawfly). In habits, 
the other species are for the most part probably similar to these. Some 
confusion which has grown up with respect to some of the light-colored 
forms is referred to in the table for the separation of the species. 
TABLE OF SPECIES. 
Females. 
A. Prevailing color black; pectus always black. 
Stigma narrow, usually straight on lower margin or strongly acuminate, 
elongate, more than three times as long as wide. 
Head, thorax, and abdomen black above. 
Stigma and femora brown or black. 
Abdomen beneath black.-..............----..--.-- 1. vicinalis Cr. 
Abdomen pale beneath. 
Orbits black. 222 Ss5233 6 eect eee 2. occidentalis n. sp. 
Orbits ppailé: 423: <i Beas eee ee cee 3. latus n. sp. 
Stigma and femoral pales -sessss— == seme ese eee 4, pacificus n. sp. 
Head and thorax black; abdomen more or less pale. ;' 
Abdomen with broad lateral pale stripe ......---.---- 5. limbatus Cr. 
Abdomen with broad, transverse yellow band. ---- 6. latifasciatus Cr. 
Stigma broad, rounded on lower margin, not much more than twice as long as 
wide. 
Head and thorax black; venter of abdomen pale; dorsal ares always more 
or less black, except sometimes terminal ones. 
Bemora black asset so-so eee eee eee Y.. 7. ventralis Say, 
ind femorajonily, blacks === ese eae eee 8. marlattti Dyar. 
Femora pale; orbits black or strongly infuscated. 
Coxe black; abdomen black above, except narrow apex of some 
ofsdorsaliancs' sce see a ene eee Hee eee 9. atriceps 1D. sp. 
Coxe pale; abdomen with narrow transverse brown stripes on 
dorsal ares, sometimes limited to basal segments, mostly pale; 
Sheath pale: s.ciock se osiseine 2s weoeiete ee see 10. coloradensis n. sp. 
