Argentina, Bolivia (type locality), Peru, Brasil (SC, PR, PA), Guianas, Costa Rica, Honduras. Costa Rica: scattered localities above 800m.
Regarding this species, Brown (1965) states:
T. pusillus appears to be a soil dweller in cultivated and pampas areas as well as in forest (Kempf, 1961). It also seems to exist at higher elevations (e.g., in a coffee plantation at Venecia, near Medellin, Colombia). Probably it is strongly subterranean in foraging and nesting habits.
In Costa Rica I have collected this species from the north slope of Volcan Barba at 800m, just west of Monteverde at 900m, Cerro Cacao in the Guanacaste Conservation Area, and Pittier Biological Station at 1670m in the Cordillera de Talamanca. The Cerro Cacao collection was from beneath a stone under the stunted forest of Cerro Pedregal. The other collections were from Winkler samples of sifted litter from the forest floor. The collection from near Monteverde contained workers and a dealate queen.
Brown, W. L., Jr. 1965. Contributions to a reclassification of the Formicidae. IV. Tribe Typhlomyrmecini (Hymenoptera). Psyche (Camb.) 72:65-78.
Emery, C. 1906 ("1905"). Studi sulle formiche della fauna neotropica. XXVI. Bull. Soc. Entomol. Ital. 37:107-194.
Kempf, W. W. 1961. A survey of the ants of the soil fauna in Surinam (Hymenoptera: Formicidae). Stud. Entomol. 4:481-524.
Menozzi, C. 1927. Formiche raccolte dal Sig. H. Schmidt nei dintorni di San Jose di Costa Rica. Entomol. Mitt. 16:266-277.
Found most commonly in these habitats: 22 times found in mature wet forest, 18 times found in montane wet forest, 10 times found in tropical wet forest, 1 times found in 2º lowland rainforest, 1 times found in isolated clearing in mature wet forest area, open lawn area at edge of building., 3 times found in ridgetop cloud forest, 1 times found in tropical moist forest, 2 times found in lowland wet forest, 1 times found in wet forest, 1 times found in moist forest, ...
Collected most commonly using these methods or in the following microhabitats: 38 times miniWinkler, 13 times MaxiWinkler, 6 times search, 4 times Winkler, 1 times fogging, 1 times Malaise, 1 times Mini Winkler, 1 times pan trap, carrion baited times PF
Elevations: collected from 50 - 1670 meters, 679 meters average