AntWiki: The Ants --- Online
Key to workers of Monomorium known from the United States and Canada. Monomorium inquilinum, Monomorium pergandei and Monomorium talbotae are not included as they lack the worker caste.
1
- Dorsal and posterior faces of propodeum equal in length => 2
- Dorsal face of propodeum shorter than posterior face => 3
- Dorsal face of propodeum longer than posterior face => 4
2
- Mesopleuron punctate; fewer than 8 setae projecting above dorsum of mesosoma => Monomorium cyaneum
- Mesopleuron not punctate; more than 10 (rarely 8 or 9) setae projecting above dorsum of mesosoma => Monomorium ebeninum
3
- Fewer than 6 setae projecting above dorsum of mesosoma; occurs in northeastern U. S. => Monomorium emarginatum
4
- Mesopleuron punctate or otherwise sculptured => 5
5
- Anterior clypeal margin weakly concave medially, clypeus weakly bicarinate => 6
- Anterior clypeal margin strongly concave medially, clypeus strongly bicarinate => 7
6
- Body uniform yellow with head, mesosoma and anterior section of gaster essentially the same color (posterior section of gaster often dark); petiolar node higher, node narrower, anterior and posterior faces converging only slightly dorsally => Monomorium pharaonis
- Body strongly bicolored with head and gaster much darker than mesosoma, or occasionally body dark brown and essentially uniformly colored (gaster always uniformly dark); petiolar node lower, node broader, anterior and posterior faces converging more strongly dorsally => Monomorium floricola
7