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 => 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 => 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) => 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; 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 => 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 => Acanthognathus ocellatus
 * Fossae on posterior half of dorsum or head large, mostly contiguous or separated by single, simple longitudinal rugulae => Acanthognathus lentus