394 bulletin: museum of comparative zoology. 



12. Mesonotum immaculate dakotensis Emery. 



Mesonotum with three dark spots. 



dakotensis var. viontigena Wheeler. 



13. Gaster very smooth and shining, with very short, sparse, indis- 



tinct pubescence 14 



Gaster opaque or subopaque, with denser, longer pubescence. . 16 



14. Length 7-8 mm. Head and thorax deep red, the former not 



infuscated. Wings deeply infuscated at the base. 



truncicola obscurivcntris Mayr. 



Length 8-9 mm. Head and thorax dull, yellowish red, both 



more or less infuscated. Wings only slightly infuscated. ... 15 



15. Posterior border of pronotum infuscated. 



rufa agger ans, nom. no v. 

 Pronotum and other portions of thorax more extensively infus- 

 cated rufa aggerans var. melanotica ILmevy. 



16. Head and thorax without erect hairs above 17 



Head and thorax wdth erect hairs above 19 



17. Length 6.5-8 mm. Ground color of head, thorax, and petiole 



sordid brownish yellow, gaster blackish brown, not paler at 



the base truncicola niuccsccns, subsp. nov. 



Length 8-10 mm. Ground color of head, thorax, and petiole 

 bright or deep red, base of gaster red 18 



18. Pubescence on gaster rather sparse and short, so that its surface 



is subopaque . . truncicola inicgroides var. haemorrhoidalisl*]mery . 



Pubescence on gaster longer and denser so that its surface is more 



opaque truncicola integra Nyl. 



19. Hairs on upper surface of head and thorax sparse; wings opaque 



gray truncicola integroides Emery. 



Hairs on upper surface of head and thorax somewhat more abun- 

 dant; wings distinctly infuscated at the base. 



truncicola integroides var. coloradensis, var. nov. 



MiCROGYNA GROUP. 



Workers. 



Gaster shining, very sparsely and finely pubescent 2 



Gaster opaque, densely pubescent 3 



Head and thorax deep red, gaster black nepticula Wheeler. 



Head and thorax reddish yellow, gaster brown . . viorsei Wheeler. 



