Key to US Monomorium species

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

Head of Monomorium cyaneum worker

Profile of Monomorium cyaneum worker

• Mesopleuron not punctate; more than 10 (rarely 8 or 9) setae projecting above dorsum of mesosoma => Monomorium ebeninum

Head of Monomorium ebeninum worker

Profile of Monomorium ebeninum worker

3

• Fewer than 6 setae projecting above dorsum of mesosoma; occurs in northeastern U. S. => Monomorium emarginatum

Head of Monomorium emarginatum worker

Profile of Monomorium emarginatum worker

• More than 8 setae projecting above dorsum of mesosoma; occurs in northern Florida => Monomorium trageri

Head of Monomorium trageri worker

Profile of Monomorium trageri worker

4

• Mesopleuron smooth or nearly so, never punctate => Monomorium minimum

Head of Monomorium minimum worker

Profile of Monomorium minimum worker

• 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

Head of Monomorium pharaonis worker

Profile of Monomorium pharaonis worker

• 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

Head of Monomorium floricola worker

Profile of Monomorium floricola worker

7

• Occurs from New Jersey to Florida => Monomorium viridum

Head of Monomorium viridum worker

Profile of Monomorium viridum worker

• Occurs along California coast => Monomorium ergatogyna

Head of Monomorium ergatogyna worker

Profile of Monomorium ergatogyna worker