Known from rainforest and disturbed forest habitats (pine and coffee). Collections have been made from rotten wood and under bark.
Bolton (1977) - This species is a sibling of Tetramorium pacificum, differentiated from it by the strongly reduced cephalic sculpture found in validiusculum. In some respects it resembles Tetramorium cynicum of the Philippines (see there), another sibling of pacificum whose range does not appear to overlap that of validiusculum, which is restricted to New Guinea and Queensland, particularly the Cape York Peninsula.
Keys including this Species
Distribution based on Regional Taxon Lists
Distribution based on AntMaps
Distribution based on AntWeb specimens
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The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.
- validiusculum. Tetramorium pacificum subsp. validiusculum Emery, 1897c: 585 (w.) NEW GUINEA. Raised to species: Wilson & Taylor, 1967: 73. Senior synonym of longicarinum: Bolton, 1977: 104.
- longicarinum. Tetramorium longicarinum Donisthorpe, 1941h: 57 (w.) NEW GUINEA. Junior synonym of validiusculum: Bolton, 1977: 104.
Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.
Bolton (1977) - TL 3.7-4.6, HL 0.86-1.16, HW 0.74-1.10, CI 84-94, SL 0.62-0.84, SI 76-87, PW 0.56-0.74, AL 1.02-1.30 (20 measured).
Mandibles unsculptured, smooth except for pits from which hairs arise. Anterior clypeal margin with a weakly developed median impression or notch. Median portion of clypeus with three main longitudinal carinae, in some large specimens the anterior half of the clypeus feebly transversely concave. Frontal carinae strongly developed, extending back almost to the occipital margin. Eyes with maximum diameter c. 0.18-0.23. Propodeal spines long, acute, usually narrow and sometimes slightly upcurved along their length. Metapleural lobes triangular, acute and feebly upcurved. Petiole node in profile shaped as in pacificum (see Fig. 15), with the anterior face shorter than the posterior so that the convex dorsal surface slopes upwards posteriorly and the posterodorsal angle is higher than the anterodorsal. The last cannot accurately be called an angle as in this species the anterior face joins the dorsum through a curve. Dorsum of head sculptured with a series of spaced longitudinal carinae or rugulae, some of which may be short or broken. Cross-meshes are either completely absent or a few cross-meshes or anastomoses may be present occipitally, but there is never a strongly developed rugoreticulum behind the level of the eyes as is found in most species of this group, nor do cross-meshes occur in front of the level of the posterior margins of the eyes. Ground sculpture faint and inconspicuous so that spaces between rugulae and carinae on head are shiny and mostly quite smooth. Dorsal alitrunk, petiole and postpetiole usually reticulate-rugose but this is commonly reduced in density and intensity. Gaster un sculptured, smooth and shining. All dorsal surfaces of head and alitrunk with numerous long, erect or suberect hairs. Colour uniform very dark brown to black.
Bolton (1977) - Syntype workers, New Guinea: Berlinhafen (L. Biro) (Musee d'Histoire Naturelle Genève) [examined].
- Tetramorium pacificum validiusculum: Syntype, worker(s), near Aitape (as Berlinhafen), Australia, Musee d'Histoire Naturelle Genève.
- Bolton, B. 1977. The ant tribe Tetramoriini (Hymenoptera: Formicidae). The genus Tetramorium Mayr in the Oriental and Indo-Australian regions, and in Australia. Bulletin of the British Museum (Natural History). Entomology. 36:67-151. PDF (page 104, Senior synonym of longicarinum)
- Emery, C. 1897c. Formicidarum species novae vel minus cognitae in collectione Musaei Nationalis Hungarici quas in Nova-Guinea, colonia germanica, collegit L. Biró. Természetr. Füz. 20: 571-599 PDF (page 585, worker described)
- Wilson, E. O.; Taylor, R. W. 1967b. The ants of Polynesia (Hymenoptera: Formicidae). Pac. Insects Monogr. 14: 1-109 (page 73, Raised to species)