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Honduras, Costa Rica, Panama, Colombia, Venezuela. Costa Rica: Atlantic and southern Pacific lowlands.
The genus Proceratium comprises mostly rare and cryptic ants of leaf litter and soil, distributed throughout the world in both tropical and temperate zones (Baroni Urbani and de Andrade 2003). Some species of the genus are known to be specialized predators of spider eggs (Brown 1980).
In Costa Rica this species is known from lowland wet forest. The species is encountered as isolated workers in sifted leaf litter samples from the forest floor.
A much broader concept of micrommatum was adopted by Ward (1988). Baroni Urbani and de Andrade (2003) took a more fine scale view, splitting micrommatum into multiple species. The three Costa Rican species micrommatum, convexiceps, and panamense are very similar and key next to each other in Baroni Urbani and de Andrade.
Baroni Urbani, C., and M. L. de Andrade. 2003. The ant genus Proceratium in the extant and fossil record (Hymenoptera: Formicidae). Museo Regionale di Scienze Naturali-Torino, Torino, Italy.
Brown, W. L., Jr. 1980 ("1979"). A remarkable new species of Proceratium, with dietary and other notes on the genus (Hymenoptera: Formicidae). Psyche (Camb.) 86:337-346.
Roger, J. 1863. Die neu aufgefuehrten Gattungen und Arten meines Formiciden-Verzeichnisses nebst Ergaenzung einiger frueher gegebenen Beschreibungen. Berl. Entomol. Z. 7:131-214.
Ward, P. S. 1988. Mesic elements in the western Nearctic ant fauna: taxonomic and biological notes on Amblyopone, Proceratium, and Smithistruma (Hymenoptera: Formicidae). J. Kansas Entomol. Soc. 61:102-124.
Earlier (Brown 1974:82) I called attention to the doubtful status of P. convexicepsHNS Borgmeier (1957:120-122, fig. 34). Not only do samples of this complex (including new collections from Honduras: Lancetilla, near Tela; and 14 km S. La Ceiba; both in rotten logs, W. L. Brown, Jr.) vary in the development of the median clypeal process, which may be absent, weakly projecting, or strong, but it seems clear that the "Arbeiter" of micrommatumHNS against which Borgmeier (1957:118-120) compared convexicepsHNS was actually an ergatoid queen of micrommatumHNS, so that differences in head shape, eye size and petiolar thickness are apparently only allometric caste differences.
A worker specimen of P. micrommatumHNS from Honduras was dissected and proved to have maxillary palpi of 3 segments, the second segment having the "hammer-head" form characteristic of ProceratiumHNS, i.e., it is stalked from the side, and the apical segment has 3 long apical sensilla. Labial palpi with each 2 segments: basal segment narrower, apical segment claviform, with 3 long apical sensilla.
Found most commonly in these habitats: 6 times found in tropical rainforest, 6 times found in mature wet forest, 6 times found in montane wet forest, 1 times found in Rainforest, 1 times found in riparian wet forest, 1 times found in 2º lowland rainforest, 1 times found in Sendero Holdrige, 1 times found in tropical wet forest, 2 times found in Wet forest, 1 times found in rainforest edge, ...
Found most commonly in these microhabitats: 25 times ex sifted leaf litter, 1 times Wet forest. Ex sifted leaf litter., 1 times Hojarasca, 1 times St. 804, collecting in second Sloanea, along a branch 24m high, covered with aro, 1 times sifted litter (leaf mold, rotten wood), 1 times on tree trunk, 1 times on bromeliads, 0 times Ex rottn. log, 1 times Camino toma de Agua, 1 times bajo de M/01.
Collected most commonly using these methods: 13 times MaxiWinkler, 8 times MiniWinkler, 5 times Winkler, 3 times litter sample, 2 times Berlese, 2 times flight intercept trap, 2 times search, 1 times Berlese, leaf litter, 1 times Pitfall.
Elevations: collected from 5 - 1219 meters, 347 meters average
Type specimens: type of Sysphingta micrommata: focol0932