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Proceratium is a world-wide genus of small, cryptic ants that live in rotten wood and leaf litter (Brown 1958a, b, 1974, 1980; Ward 1988, Baroni Urbani and de Andrade 2003). Brown (1980) writes:
The species of Proceratium are arthropod egg predators as far as is known. In Proceratium, P. silaceum has been observed feeding upon and storing eggs of spiders and (rarely) of another, unknown arthropod (Brown, 1958; the determination of P. silaceum was inadvertently omitted from the field and artificial nest observations). Since then, I have observed P. pergandei in Mississippi feeding on and storing spider eggs in a rotten-wood nest in nature; P. micrommatum from rotten-wood colonies from Lancetilla, near Tela, Honduras, feeding on spider eggs of two different kinds offered in the artificial nest; and P. avium carrying and storing eggs resembling spider eggs in Mauritius (Brown, 1974). Tests by me with all these species in the artificial nest failed to elicit any attempt by the ants to feed on sugary food, eggs of one or two kinds of millipedes, and various insect parts, but I did once get two P. silaceum workers to feed on a small droplet of yolk from a fresh hen's egg for periods of up to about 2 minutes at a time in the artificial nest.Observations of P. silaceum in artificial nests indicate that in this species the reflexed gastric tip is used to tuck the slippery eggs forward toward the mandibles when the eggs are being carried by the ants. Eggs of prey are stored in the ant nest in large numbers, recalling seed storage by the true harvester ants in subfamily Myrmicinae.
See Baroni Urbani and de Andrade (2003) for the most recent review of the genus.
Key to Proceratium Species Known from Costa Rica, Based on Workers
10a. Petiolar node "bun-shaped," broad at the base, with anterior and posterior faces converging to a rounded summit: 100
10b. Petiolar node in the form of a thick, erect scale, with anterior and posterior faces subparallel: mancum
100a. Mid-tibia lacking a pectinate apical spur: 200
100b. Mid-tibia with a pectinate apical spur: goliath
200a. Mesosoma more convex in profile; integument sculpture relatively impressed: convexiceps
200b. Mesosoma more elongate; integument sculpture more superficial: 300
300a. Webers length less than 0.95mm: micrommatum
300b. Webers length greater than 1.05mm: panamense
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. 1958a. Contributions toward a reclassification of the Formicidae. II. Tribe Ectatommini (Hymenoptera). Bull. Mus. Comp. Zool. 118:173-362.
Brown, W. L., Jr. 1958b. ("1957"). Predation of arthropod eggs by the ant genera Proceratium and Discothyrea. Psyche (Camb.) 64:115.
Brown, W. L., Jr. 1974. A remarkable new island isolate in the genus Proceratium (Hymenoptera: Formicidae). Psyche (Camb.) 81:70-83.
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.
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.
Page author:
John T. Longino, The Evergreen State College, Olympia WA 98505 USA.longinoj@evergreen.edu
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