Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
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Additional images: line drawing from Kempf and Brown 1968 (low resolution, high resolution); lateral view of queen (low resolution, high resolution).
Range
Costa Rica. Atlantic slope, sea level to 1100m in Cordillera Volcanica Central.
Identification
Petiolar node "bun-shaped," broad at the base, with anterior and posterior faces converging to a rounded summit; mid-tibia with a pectinate apical spur; HW (without eyes) 1.50mm.
Natural History
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). Regarding goliath, Kempf and Brown (1968) describe the collection of the type series as follows:
Holotype, together with 5 paratypes and another worker that was dissected in the field, collected in disturbed wet lowland rain forest about 2 km beyond (NW of) the steel bridge over the Rio Toro Amarillo, near Guapiles, Limon Province, Costa Rica (W. L. Brown, Jr., leg.) on 3 and 4.III.1966. The ants were in and under a fragment of rotten log about 75 cm long and 35 cm thick that was found lying in the middle of a wide, recently cleared trail. The same piece of wood held pockets containing 20-30 or more workers of Basiceros manni, but although the log was reduced to small fragments over two days, the queen and brood of neither species could be found. The Proceratium, being so unusually large, and also more active than one finds other members of the genus, was originally taken for Gnamptogenys (=Alfaria) simulans.
Recently Rob Dunn collected the first queenright colony:
During the winter of 2001, I collected a second colony in a rotten stick in Cuatro Rios, near Guapiles. The colony consisted of 25 individuals. When the colony was first encountered, the queen was walking away from the colony with eggs in her gaster. The log (roughly a foot long and 3 inches diameter) was rotten enough to break in my hands. When I found the colony all the workers were together and the queen was in a separate"chamber" a few centimeters away. The queen was the most active in the bunch and the first to try to leave when I put a light on the colony, so she may have already been trying to go when I found her at the edge of the colony in a chamber-like space. When I inititally encountered the queen she was carrying what looked like her eggs tucked under her gaster. She was the only one I saw carrying anything. I was only able to find a few larvae and no cocoons. Roughly half of all of the workers are light yellow callows (see image). Over a period of several days, I offered the colony several different kinds of small (a few millimeter) spider eggs. I never saw the colony eat any of the eggs.The colony was host to many small mites, which attached to the gasters, heads and legs of the ants. In the colony of 25 individuals there were roughly 15 mites.
Images taken by R. Dunn of specimens found at Cuatro Rios, near Guapiles. At left a P. goliath queen. At right a partial view of the colony.
P. goliath worker with head mite.
Jim Wetterer collected a colony at La Selva Biological Station in June 1996. It was under a coconut hust at the soil interface. There were 1 dealate queen, 105 workers, 15 alate males and 3 alate females. (Reported to me by Mike Kaspari, 27 Mar 2003.)
I found a nest at the Cantarrana site, 300m in Braulio Carrillo National Park. I was at the edge of a stream, digging into a clay bank with a machete, following a Pheidole tunnel, and by accident uncovered a Proceratium nest. Workers and brood tumbled out onto the dirt pile. The first chamber I encountered was about 20x20x5mm. As I continuted excavating, I uncovered a second chamber several cm deeper. Elsewhere in the same excavation hole, about 10cm away, were subterranean termites.
Type data
Proceratium goliath Kempf and Brown 1968:94. Holotype worker: Costa Rica, Prov. Limon, Rio Toro Amarillo, near Guapiles (W. L. Brown, Jr.) [MCZC].
Literature Cited
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.
Kempf, W. W., Brown, W. L., Jr. 1968. Report on some Neotropical ant studies. Pap. Avulsos Zool. (Sao Paulo) 22:89-102.
Page authors:
John T. Longino, The Evergreen State College, Olympia WA 98505 USA. longinoj@evergreen.edu
Robert R. Dunn, Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, 06226 USA Robert.Dunn@uconn.edu
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