Key to Tetramorium tortuosum-group species of the New World

This worker key is based on: [[Media:VasquezMenesesGuzman2011Tetramorium.pdf| Vásquez-Bolaños, M., Castaño-Meneses, G. & Guzmán-Mendoza, R. 2011. New species of Tetramorium from Puebla State, Mexico. Neotropical Entomology. 40:452-455. PDF]]

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 * Tetramorium
 * Tetramorium tortuosum species group

1

 * Hairs length of antennal scape and external surface of metatibia distinctly longer than maximal diameter of corresponding appendage. Scape Index (SI) 94-99 (Mexico: Jalisco and Nayarit) . . . . . Tetramorium mexicanum


 * Hairs length of antennal scape and external surface of metatibia distinctly shorter than maximal diameter of corresponding appendage. Scape Index (SI) 79-90 . . . . . 2

2
return to couplet #1
 * Petiolar dorsal surface without sculpture. Small ants, range of head width (HW range 0.66-0.72 mm; Mexico: Jalisco and Nayarit) . . . . . Tetramorium placidum


 * Petiolar dorsal surface with sculpture. Large ants, head width (HW) between 0.77 mm and 1.0 mm . . . . . 3

3
return to couplet #2
 * Large eyes, maximal diameter greater than a quarter of the head width. Hairs length on pronotal dorsal surface and frontal carinae, shorter than maximal eye diameter; small and erected hairs (USA: Arizona and Texas) . . . . . Tetramorium hispidum


 * Small eyes, maximal diameter less than a quarter of the head width. Hairs length on pronotal dorsal surface and frontal carinae equal or greater than maximal eye diameter; longer hairs, fine and curved . . . . . 4

4
return to couplet #3
 * Dorsum of body with longitudinal ridges (Mexico: Baja California, Coahuila, Durango, Hidalgo, Jalisco, Michoacán, Nayarit, Nuevo Leon, Puebla, San Luis Potosí, Sonora, Tamaulipas and Zacatecas) . . . . . Tetramorium spinosum


 * Dorsum of body reticulated . . . . . 5

5
return to couplet #4
 * Postpetiole dorsum without ridges. Total length from 3.4 mm to 3.8 mm (Mexico: Jalisco) . . . . . Tetramorium bicolorum


 * Postpetiole dorsum with ridges. Total length from 3.8 mm to 4.0 mm (Mexico: Puebla) . . . . . Tetramorium notomelanum