Key to Nylanderia clade AC1 species of southern Mexico and Mesoamerica

1. Cephalic pubescence moderate to dense (Figs. 4A, 4B); overall color variable..................................... 2

- Cephalic pubescence absent to sparse (Fig. 4C); often uniformly yellow with thick, black setae, with specimens from Belize sometimes light to medium brown................................................................. cf. docilis

2. Overall color light to dark brown; dense cephalic pubescence (Fig. 4A); scapes relatively short, surpassing posterior margin by no more than a third of their length (SI <133)............................................................... 3

- Overall color variable; if overall color is brown or reddish-brown. then cephalic pubescence moderate (Fig. 4B); if overall color is yellow, then cephalic pubescence moderate (Fig. 4B) to dense (Fig. 4A); scape length variable...................... 6

3. Posterior face of propodeum about as long as or slightly longer than dorsal face; ranging across southern Mexico and Central America............................................................................................ 4

- Posterior face of propodeum about twice as long as dorsal face; ranging across southwestern North America from central Mexico to Utah (Fig. 2)...................................................................... austroccidua

4. Medium to dark brown with antennae, mandibles, and tarsi yellow in contrast to body; head and gaster concolorous with mesosoma; meso- and metacoxae lighter in color than mesosoma; scapes surpassing posterior margin by about a third of their length (SI ≥ 130)...................................................................................... 5

- Light brown with antennae, mandibles, and tarsi concolorous with body; sometimes bicolored with medium brown head and gaster; meso- and metacoxae concolorous with mesosoma; scapes surpassing posterior margin by less than a quarter of their length (SI <130).............................................................................. breviscapa

5. Dark brown, with whitish meso- and metacoxae strongly contrasting with mesosoma; fine cuticular microsculpture resulting in moderate to strong blue iridescence on head and mesosoma............................................. contraria

- Medium to dark brown, with meso- and metacoxae somewhat lighter than mesosoma; cuticle smooth and shiny, with no microsculpture and without blue iridescence............................................................ polita

6. Overall color variable, but with head and mesosoma concolorous with gaster; cephalic pubescence dense (Fig. 4A) if overall color is yellow, cephalic pubescence moderate (Fig. 4B) if overall color is brown................................... 7

- Strongly bicolored, with yellow to yellow-brown head and mesosoma and medium to dark brown gaster; cephalic pubescence moderate (Fig. 4B).............................................................................. mosaica

7. meso- and metacoxae at most somewhat lighter than mesosoma, not whitish...................................... 8

- Meso- and metacoxae whitish, strongly contrasting with mesosoma............................................. 9

8. Medium to dark reddish-brown; scapes relatively long, surpassing posterior margin by more than a third to nearly half their length (SI ≥ 140); moderate cephalic pubescence (Fig. 4B); propodeum low and evenly rounded, with posterior face at most slightly longer than dorsal face; found in Guatemala, possibly Honduras ..................................... mendax

- Color variable; scapes relatively short, surpassing posterior margin by about a quarter to a third of their length (SI <140); cephalic pubescence moderate (Fig. 4B) in dark specimens and dense (Fig. 4A) in yellow specimens; propodeum high and evenly rounded, with posterior face steep and at most slightly longer than dorsal face; found in Costa Rica ............ usul

9. Medium to dark reddish-brown; macrosetae relatively thick and black, strongly contrasting in color with body; antennae, mandibles, and tarsi concolorous with body; overall cuticle finely microsculptured, giving matte appearance and strong blue iridescence; erect setae on scapes relatively sparse (SMC <7); apex of petiole scale without pair of small, erect setae; compound eyes relatively large (REL> 19); scapes relatively long, surpassing posterior margin by nearly half their length (SI ≥ 140); metatibiae relatively long (HTI ≥ 125); mesosoma relatively long (BLI> 146); relatively large in overall size (TL = 1.99–2.52)..................................................................................... lazulina

- Light to medium reddish-brown; macrosetae relatively thin and concolorous with body; antennae, mandibles, and tarsi yellow to yellow-brown, contrasting with body; overall cuticle lightly microsculptured and with subtle blue iridescence; erect setae on scapes relatively abundant (SMC ≥ 7); apex of petiole scale bearing a pair of small, erect setae; compound eyes relatively small (REL ≤ 19); scapes relatively short, surpassing posterior margin by less than a quarter of their length (SI <130); metatibiae relatively short (HTI <115); mesosoma relatively short (BLI ≤ 146); relatively small in overall size (TL = 1.71–2.24).................................................................................................... luceata