Key to species of Patagonomyrmex

Workers

1 Dorsum of promesonotum with subparallel rugae to rugoreticulate, interrugae strongly granulate-punctate, dull; rugae on cephalic dorsum continue to posterior margin of head (Figure 2) ......................................... angustus

- Dorsum of promesonotum smooth and shining, lacking rugae; rugae on cephalic dorsum rarely continue to posterior margin of head (Figures 6, 9) .................................................................................... 2

2 Body mostly concolorous blackish to black (Figure 6) ................................................. laevigatus

- Head and mesosoma light orangish-red, gaster slightly darker to brownish (Figure 9) ......................... odoratus

Queens

1 Mesoscutum and mesoscutellum with weak to moderately coarse longitudinal rugae, interrugae weakly to strongly granulate- punctate; inferior propodeal spines elongate, length similar to that of superior propodeal spines (Figure 3) ....... angustus

- Mesoscutum and mesoscutellum smooth and shiny; inferior propodeal spines triangular, much shorter than superior propodeal spines (Figures 7, 10) ................................................................................ 2

2 Body concolorous black (Figure 7) ................................................................ laevigatus

- Body orangish to orangish-brown (Figure 10) ........................................................ odoratus

Males

1 Mesopleura, metapleura, pronotal sides, and dorsum of propodeum strongly granulate, dull, with a beaded appearance; at least several hairs on ventral surface of head and those protruding from mandibles approach to exceed MOD; scapes usually long, reaching to near posterior margin of eye (Figure 4) .................................................... angustus

- Mesopleura, metapleura, pronotal sides, and/or dorsum of propodeum with weak to strong rugae; no hairs on ventral surface of head or those protruding from mandibles approach MOD; scapes short, reaching only slightly beyond anterior margin of eye (Figures 8, 11) ....................................................................................... 2

2 In profile, juncture between cephalic dorsum and posterior declivity (near posterior margin of ocelli) weakly angulate to rounded; posterior declivity weakly convex to weakly concave (Figure 8) .................................. laevigatus

- In profile, juncture between cephalic dorsum and posterior declivity strongly angulate; posterior declivity strongly concave (Figure 11) ................................................................................... odoratus