Despite being widely distributed across the Fijian archipelago, workers of Pristomyrmex tsujii are rarely encountered in the field, although males have been collected in Malaise traps with some frequency.

The strongly distended gasters of the ergatoid queens are presumably equipped with functional ovaries, but a more thorough examination of fresh material would be required to verify their reproductive potential.

The only congeneric species with an unarmed propodeum is Pristomyrmex inermis from New Guinea which also belongs to the levigatus group.

Pristomyrmex tsujii has a more nodiform petiole, a stronger median clypeal tooth, and more abundant foveae between the frontal carinae.

[2] Head shape is circular with posterior margin flat to feebly concave medially in full-face view.

Frontal carina is distinct and extends just past the level of the posterior eye margin.

Eye moderate-sized, approximately same size as antennal socket, 3–4 facets along longest diameter.

Dorsum of mesosoma in profile view evenly arched, broken only by a weak impression separating the mesonotum from the propodeum.

Petiole and postpetiole are smooth and shining, each with a weak lateral longitudinal carina on both sides.

Dorsal surface of head with numerous erect to suberect long hairs originating from center of foveolae.

[3] Closely resembling the worker in the structure of mandibles, clypeus, petiole, postpetiole and gaster in addition to sculpture, color and pilosity.

Dorsum of head is covered with scattered to abundant weakly impressed foveolae and smaller shallow punctures.

Dorsum of mesosoma is similar to alate queen with one or two additional pairs of erect hairs than worker.

[4] Closely resembling worker in the structure of the mandibles, clypeus, petiole, postpetiole and gaster in addition to sculpture, color and pilosity with the following differences.

Dorsum of head is covered with scattered to abundant weakly impressed foveolae and smaller shallow punctures.

Propodeal lobes are obtusely triangular with a blunt or rounded apex; sometimes reduced to weak flanges.

Sides of the mesosoma are smooth and shining, occasionally with several short carinulae on metapleuron and propodeum.

[5] Pristomyrmex tsujii varies in the abundance of the cephalic foveae, propodeal armament and petiolar node shape.

In Koro (the type locality) and Gau the specimens exhibit a sparse scattering of foveae and punctures usually separated from each other by a distance exceeding their diameters.

None of the Koro specimens are armed even with denticles and the petiolar node is relatively broad in profile with a weakly convex posterior face.

Workers from both islands have an unarmed propodeum, like those from Koro, but the petiolar node is narrower in profile with a weakly concave posterior face.