Key to Acanthognathus Species

Key to Acanthognathus species based on workers and queens (modified by Galvis & Fernandez (2009) from Brown & Kempf (1969)).

1

 * Dorsum of head smooth and shining, without any fossae or rugulose-punctulate sculpture => 2
 * Dorsum of head sculptured, at least with numerous distinct round fossae on the disc, intervals smooth or rugulose => 3

2

 * Mandibles longer than head in full-face view, each with two or three long spiniform teeth before the apex (Fig. 6); anterior part of head, especially in the region in front of the eyes with a few indistinct fossae; lower portions of sides of mesosoma and petiolar peduncle, in front and behind, minutely and densely punctulate => Acanthognathus teledectus
 * Mandibles not longer than head in full-face view, preapical inner borders unarmed; body completely smooth and shining (Figs. 2-4) => Acanthognathus laevigatus

3

 * Petiole with very long, slender peduncle, about three times as long as its node, which is short and transverse as seen from above (Fig. 7) => Acanthognathus stipulosus
 * Petiolar peduncle slender, but less than twice as long as its node, which is oval and at least as long as broad as seen from above => 4

4

 * Presence of transverse rugae on the posterior cephalic angles (fossil ant from Dominican amber; Fig. 8) => Acanthognathus poinari
 * Transverse rugae on the posterior cephalic angles absent => 5

5

 * Antennal scapes short, chord less than 90% as long as mandibles seen in dorsal view (Fig. 1); preapical area of inner mandibular border with (usually two or more) irregular denticles => Acanthognathus brevicornis
 * Antennal scapes with chord about as long as, to much longer than, the mandibles as seen in dorsal view; inner mandibular borders without preapical denticles, though a submedian welt may be present => 6

6

 * Mandibles shorter (MI 60-75); dorsum of head completely, densely, and rather finely rugulose, with interspersed fossae numerous, small, and crowded, so that the surface, including the area around the eyes, is essentially opaque (Fig. 9) => Acanthognathus rudis
 * Mandibles longer (MI > 75); dorsum of head loosely sculptured and more or less shining, fossae large and shallow, with smooth spaces or simple longitudinal rugulae between some rows; at least a strip bordering each eye mesially nearly smooth, shining => 7

7

 * Fossae on posterior half of dorsum of head smaller, mostly separated by flat, smooth spaces (Fig. 5) => Acanthognathus ocellatus
 * Fossae on posterior half of dorsum or head large, mostly contiguous or separated by single, simple longitudinal rugulae (Fig. 10) => Acanthognathus lentus