Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
Mandibles with large apical tooth, smaller subapical tooth, and series of 12 or more minute denticles of more or less uniform size; mandibles smooth and shiny; median portion of clypeus protruding and the anterior margin of clypeus recessed, such that in face view the median portion of the clypeus partially obscures the anterior margin; occipital carina visible in face view; propodeal suture deeply impressed; propodeum with dorsum longitudinally depressed, the sides of the dorsal face forming two gently rounded ridges which rise anteriorly to form raised bosses at the posterior margin of the propodeal suture; ventral margin of postpetiole convex, protruding; color red brown. Size and relative scape length highly variable. Santa Rosa specimen: HW 0.57; HL 0.77, SL 0.89; WL 1.08. Hitoy Cerere specimen: HL 0.87, SL 1.04, WL 1.31. Hitoy Cerere specimen from same litter sample: HL 0.79, SL 0.99.
Widespread in Neotropics from Argentina to Mexico. Costa Rica: widespread in lowlands.
Mann (1916) stated "A good series of workers were taken at Ceiba and San Juan Pueblo, nesting in the ground and in rotten logs. It is a timid species and very active when disturbed." Weber (1940) reported three collections of silvestrii (reported as wheeleri; wheeleri synonymized with silvestrii by Kempf and Brown 1968) found in nests of Cyphomyrmex costatus on Barro Colorado Island, Panama. In one nest he found a dealate queen. In a second nest he found a dealate queen and a worker. In a third nest he found 3 dealate queens and 55 workers. However, Brown (in Kempf and Brown 1968) reported finding four nests, two from Barro Colorado Island, one from Cerro Campana, Panama, and one from Santa Teresa, Brazil, that "were nesting independently of other ants so afar as he could tell." Brown's two Barro Colorado nests were "inside a small clod of soil in the leaf litter," and "in a small piece of rotten wood, 10 mm deep and 15 mm wide, also contained many termites." Diniz collected isolated nests of silvestrii in Betim, MG, Brazil (reported in Brandao 1990). Kempf and Brown (1968) suggested that the species is "not so much a parasite as it is a mass-foraging predator that specializes in raiding, and sometimes occupying, the nests of small Attini."
In Costa Rica, I have seen the species only from Winker samples. The samples were from Hitoy Cerere, Osa Peninsula, and Santa Rosa (Bosque humedo).
Brandao, C. R. F. 1990. Systematic revision of the Neotropical ant genus Megalomyrmex Forel (Hymenoptera: Formicidae: Myrmicinae), with the description of thirteen new species. Arquivos de Zoologia (Sao Paulo) 31:411-481.
Kempf, W. W., Brown, W. L., Jr. 1968. Report on some Neotropical ant studies. Papeis Avulsos Zool. 22:89-102.
Mann, W. M. 1916. The Stanford Expedition to Brazil, 1911, John C. Branner, Director. The ants of Brazil. Bull. Mus. Comp. Zool. 60:399-490.
Weber, N. A. 1940d. The biology of the fungus-growing ants. Part VI. Key to Cyphomyrmex, new Attini and a new guest ant. Revta Entomol. 11:406-427.
John T. Longino, The Evergreen State College, Olympia WA 98505 USA. firstname.lastname@example.org