Ants

The methods of finding ants in the field are low-tech but ingenious. Direct observation of foragers on the ground and in the vegetation is one way, but tools are often used including a “Davis Sifter” and a beating sheet. A Davis Sifter is a screened pan used like a sieve to quickly separate ants from leaf litter, white a beating sheet is a square meter sheet of white nylon. The sheet is held underneath while a plant is shaken with a stick, causing ants to fall onto the nylon. Twigs are inspected for ants’ nests and a UV light trap is used to collect winged adults at night. 

The survey site was located in a grassland area surrounded by evergreen forest, which is somewhat problematic for insects since most of the grassland burns every year. Our research focused on an evergreen forest area where shrubs and trees have settled, as that creates refuge areas for ants during fires either under a thick leaf litter or high in the trees. 

On site identification yielded an initial list of genera and species:

Anochetus sp.
Anoplolepis gracilipes
Camponotus spp.
Cataulacus spp.
Crematogaster spp.
Diacomma sp.
Gesomyrmex sp.
Leptogenys spp.
Odontomachus sp.
Oecophylla smaragdina
Pachycondyla sp.
Paratrechina longicornis
Pheidole spp.
Pheidologeton spp.
Polyrhachis spp.
Pyramica sp.
Strumigenys sp.
Tetraponera sp.

 

The collection also contained many unidentified Ponerinae, Myrmicinae, and Dolichoderinae.

A major discovery was a colony of Gesomyrmex (possibly G. tobiasi) found in the vicinity of the camp. Some workers were initially found foraging around the camp area, and were baited with live termites and mosquitoes. After a few hours the nest was found inside a branch of 5 cm diameter, the entrance being a tiny hole of 1 mm diameter. The branch was cut open, delivering dozens of workers of different sizes, along with larvae and nymphs. Another colony was located nearby and left undisturbed for further study on their behavior.

 

This genus is in the tribe Gesomyrmicini and its closest and only living relative genus is Santschiella from Africa with a single known species, G. kohli. Gesomyrmex was first described from a fossil species. A new species of Gesomyrmex, G. tobiasi was described in 2004 by Dubovikoff from a single queen found in Hoa Binh Province (800 km away from the nest found during this RAP survey). In 1949, Cole published the last note on this genus. “The population of their nests is small, and they live in small branches of trees. Members of this genus are very rare and ancient forms.” Considering this, the colony may be G. tobiasi and hence a range extension and a significant increase in the numbers of specimens known of this species, or an entirely new species of Gesomyrmex.

Download the full preliminary report: Cambodia Virachey Park 2007 Preliminary RAP Report (PDF - 3.63 MB)

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