Key to Trachymyrmex of the Jamaicensis species group (workers)

1 With the body in side view, length of lateral pronotal and anterior mesonotal projections notably different, either the mesonotal is much bigger than pronotal (Fig. 10), or appears as a multitubercular low tumulus (Fig. 16) ...................................................................................................................................................... 2

- Lateral pronotal and anterior mesonotal projections almost of the same size or the mesonotal a little shorter, but always spine-like ...................................................................................................................... 3

2 Lateral pronotal spine-like projections shorter and slenderer than anterior mesonotal ones; midpronotal projections present; pronotal inferior corner and anterior margin of katepisternum unarmed; postpetiole in dorsal view trapezoidal, little broader behind than in front, its postero-dorsal border straight .................... ............................................................................................................ T. isthmicus Santschi (Figs 9–14, 30)

- Lateral pronotal spine-like projections longer than tumuliform and multituberculated anterior mesonotal ones; midpronotal projections absent or obsolete; pronotal inferior corner and anterior margin of upper region of katepisternum armed with a notable triangular tooth; postpetiole in dorsal view broader than long, its posterior border concave ............................................................ T. ixyodus n. sp. (Figs. 15–18, 30)

3 Apically spatulate curved coarse hairs distributed over the whole body (Figs. 3, 26) ............................... 4

- Curved coarse hairs apically spatulate absent over the whole body, except gaster .................................... 5

4 Antennal scape scarcely surpassing the posterior margin of head when lodged in the scrobe, with head in frontal view; anterior margin of the crenate frontal lobe with a protruded pointed tooth; propodeal spines distinctly longer than the distance between their inner bases (better seen in postero-dorsal view) .............. ................................................................................................................... T. zeteki Weber (Figs 23–26, 30)

- Antennal scape surpassing the posterior margin by nearly a third of its length, when lodged in the scrobe, with head in frontal view; anterior margin of the smooth frontal lobe unarmed; propodeal spines distinctly shorter than the distance between their inner bases (better seen in postero-dorsal view) ............................. .................................................................................................................. T. atlanticus n. sp. (Figs 1–5, 30)

5 Base of the anterior mesonotal spine thicker than the base of lateral pronotal ones; midpronotal projections absent or rarely represented by a pair of minute separate spines; supraocular projection spine-like; head and gaster darker than yellowish brown mesosoma; last funicular segments as dark as antennal scapes ............................................................................................. T. jamaicensis (André) (Figs 19–22, 29)

- Base of the anterior mesonotal spine almost as thin as the base of lateral pronotal ones; midpronotal projection represented by a single truncate tooth; supraocular projection absent or vestigial; the whole body dark reddish brown; last funicular segments lighter than other antennal segments ..................................... ............................................................................................... T. haytianus Wheeler & Mann (Figs 5–8, 29)