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Costa Rica, Panama.
Stegomyrmex manni is an uncommon ant found on the forest floor of mature rainforest. I only know it from Winkler samples of sifted litter from the forest floor. I have collected specimens at Manuel Antonio National Park, Carara Biological Reserve, Penas Blancas east of Monteverde, and Hitoy Cerere Biological reserve. Ronald Vargas collected an alate queen at La Selva Biological Station.
Diniz (1990) revised the genus and recognized three species: manni from Panama, connectens from Peru and Bolivia, and vizottoi from eastern and southeastern Brazil and Paraguay. All three are quite similar in habitus and the currently known ranges are allopatric.
Hoelldobler and Wilson (1986) illustrated and discussed the special soil-binding setae of Stegomyrmex manni (as connectens) (see images above). Workers accumulate a thin layer of encrusted mud held in place by the specialized setae, and it is presumed that this is an adaptation to enhance the ant's camouflage. They observed a similar coating in some Basicerotinae.
Diniz and Brandao (1993) made the first observations on the foraging and nesting habits of any Stegomyrmex. Their observations were of S. vizottoi in southeastern Brazil. Workers were specialized predators of millipede eggs. Workers foraged solitarily, moving slowly in shaded areas, probing in small cracks and cavities in the soil. They seemed to use their faces like a shovel, tucking their antennae in the antennal scrobes and pushing soil away with the face. When a millipede egg was found it was grasped with the gular surface of the head and the undersurface of the mandibles and then returned to the nest.
One nest was examined in detail (Figure 4 from Diniz and Brandao 1993, small, large). The entrance was in a vertical soil bank. A tunnel extended about 40cm to an outer chamber, in the roof of which was a funnel leading to a main chamber. The main chamber contained the colony queen and all brood. There were millipede egg shells in the outer chamber but none in the main chamber. The total worker population was 76. A second nest contained about 300 workers, 22 alate queens, 7 dealate queens, and brood.
Diniz, J. L. M. 1990. Systematic revision of the tribe Stegomyrmicini with description of a new species (Hymenoptera, Formicidae). Rev. Bras. Entomol. 34:277-296.
Diniz, J. L. M., and C. R. F. Brand‹o. 1993. Biology and myriapod predation by the Neotropical myrmicine ant Stegomyrmex vizottoi (Hymenoptera: Formicidae). Insectes Sociaux 40:301-311.
Hšlldobler, B., and E. O. Wilson. 1986. Soil-binding pilosity and camouflage in ants of the tribes Basicerotini and Stegomyrmecini (Hymenoptera, Formicidae). Zoomorphology (Berl.) 106:12-20.
Found most commonly in these habitats: 10 times found in Cerca de los Laboratorios, 4 times found in lowland rainforest, 6 times found in montane wet forest, 3 times found in wet forest, 3 times found in mature wet forest, 3 times found in tropical rainforest, with big trees, probably primary, 1 times found in 2nd growth forest, 1 times found in Primary wet forest, 1 times found in rainforest leaf litter, 1 times found in Sendero Tres Ríos, ...
Found most commonly in these microhabitats: 18 times ex sifted leaf litter, 10 times Claro, 1 times SCH, 1 times Hojarasca, 1 times ex sifted litter, 1 times ex sifted leaf litter and rotten wood.
Collected most commonly using these methods: 15 times Malaise, 7 times Winkler, 7 times maxiWinkler, 6 times miniWinkler, 2 times Mini Winkler, 1 times berlesate, 1 times Davis sifter.
Elevations: collected from 20 - 1040 meters, 254 meters average