Costa Rica (Monteverde, Hitoy Cerere Biological Reserve).
The genus Octostruma is known only from the New World tropics, from southern Mexico and the West Indies to northern Argentina (Brown and Kempf 1960). It is a part of the "cryptobiotic" fauna: small, slow-moving ants that live in rotten wood and leaf litter. The very similar genus Eurhopalothrix is known to be predaceous on small, soft-bodied arthropods (Brown and Kempf 1960, Wilson 1956, Wilson and Brown 1985).
Workers and nests are extremely difficult to see in the field. Some species camouflage themselves with layers of soil (Hoelldobler and Wilson 1986). As a result of their cryptic nature, they were considered extremely rare until the 1960's. But increasing use of Winkler and Berlese sampling has shown Octostruma to be relatively common. I encounter them in most Winkler samples from wet forest sites in Costa Rica.
I know this species from 4 Winkler samples from the Monteverde cloud forest (all from ridge-top cloud forest, not from moist forest lower in community), and one Winkler sample from 200m elevation rainforest in Hitoy Cerere Biological Reserve.
Brown, W. L., Jr., Kempf, W. W. 1960. A world revision of the ant tribe Basicerotini. Stud. Entomol. (n.s.) 3:161-250.
Hoelldobler, B., Wilson, E. O. 1986. Soil-binding pilosity and camouflage in ants of the tribes Basicerotini and Stegomyrmecini (Hymenoptera, Formicidae). Zoomorphology (Berl.) 106:12-20.
Wilson, E. O. 1956. Feeding behavior in the ant Rhopalothrix biroi Szabo. Psyche (Camb.) 63:21-23.
Wilson, E. O., Brown, W. L., Jr. 1985 ("1984"). Behavior of the cryptobiotic predaceous ant Eurhopalothrix heliscata, n. sp. (Hymenoptera: Formicidae: Basicerotini). Insectes Soc. 31:408-428.
Found most commonly in these habitats: 17 times found in tropical moist forest, 6 times found in tropical rainforest, 8 times found in 2º lowland tropical rainforest, 5 times found in 2º lowland rainforest, 6 times found in mature wet forest, 5 times found in tropical wet forest, 1 times found in Primary wet forest, 1 times found in montane wet forest, 1 times found in ridgetop cloud forest, 1 times found in lowland rainforest, ...
Collected most commonly using these methods or in the following microhabitats: 38 times MiniWinkler, 11 times MaxiWinkler, 1 times winkler, 1 times Berlese, 1 times Mini Winkler
Elevations: collected from 50 - 990 meters, 340 meters average