Article

Ants

From Munshipedia, the MBRAS digital historical encyclopedia

Ants

Ants constitute a remarkably diverse and ecologically significant component of the insect fauna of the Malay Peninsula and the surrounding islands. The earliest substantial documentation of the region’s ant fauna appears in the work of H. Overbeck, whose fieldwork between November 1912 and June 1914 across Singapore, the Riau Archipelago, Negri Sembilan, and Johore yielded more than 190 distinct ant taxa from twelve collecting sites, including the description of one new genus, one new subgenus, sixteen new species, thirteen new subspecies, and fifteen new varieties [1, p. 26]. Earlier, H. N. Ridley had drawn attention to the behavioural ecology of the caringa ant (Formica gracilipes, Gray), documenting its nest-building, combat, and feeding habits in the Straits Settlements [2]. Together, these and other contributions establish that ants in the region occupy a wide range of ecological niches—from arboreal leaf-nesters to subterranean colonists, from commensal household pests to participants in complex tripartite symbioses with plants and scale insects—and that their study in the region has a history spanning from the 1890s through the 1920s and beyond.

Taxonomic Scope and Faunal Composition

The most comprehensive taxonomic treatment of the region’s ant fauna in the Society’s literature is Overbeck’s 1924 catalogue, which presents a species list drawn from material collected over approximately twenty months [1, p. 25]. The collecting grounds comprised twelve localities, the principal one being the collector’s own garden at the seventh mile, Bukit Timah Road, an area of about fifteen acres planted with fruit-trees, coconut-palms, and rubber-trees [1, p. 25]. The remaining sites included Bukit Timah Hill, Jurong Road, Chua Chu Kang Road, Mandai Road, Ulu Beri, Ayer Terjun, Pulau Bulan in the Riau Archipelago, St. Barbe (Pulau Pejantan) in the Southern China Sea, Gunong Angsi at 2,700 feet in Negri Sembilan, Perhentian Tinggi (a rubber plantation at the foot of Gunong Angsi), and Cucub in south-western Johore [1, p. 25].

The taxonomic list spans the subfamilies Dorylinae, Ponerinae, Myrmicinae, Dolichoderinae, and Camponotidae, encompassing genera such as Dorylus, Aenictus, Phyracaces, Platythyrea, Stictoponera, Odontoponera, Diacamma, Pachycondyla, Euponera, Pseudoponera, Ponera, Leptogenys, Anochetus, Odontomachus, Sima, Pheidole, Rhopalomastix, Myrmicaria, Cardiocondyla, Cremastogaster, Dilobocondyla, Prystomyrmex, Calyptomyrmex, Meranoplus, Vollenhovia, Monomorium, Solenopsis, Lophomyrmex, Pheidologeton, Oligomyrmex, Tetramorium, Rhopthromyrmex, Xiphomyrmex, Triglyphothrix, Cataulacus, Strumigenys, Proatta, Dolichoderus, Bothriomyrmex, Iridomyrmex, Tapinoma, Technomyrmex, Semonius, Plagiolepis, Acropyga, Oecophylla, Prenolepis, Pseudolasius, Overbeckia, Camponotus, Polyrhachis, and Echinopla [1, pp. 26–40].

Among the most notable taxonomic findings was the description of the new genus Overbeckia by Viehmeyer, represented by the species O. subclavata, whose colonies were found in withered bamboo and in the hollow branch of a mangosteen-tree [1, p. 36]. A new subgenus, Monomorium subg. hospitum, was erected for specimens found living together with Monomorium floricola in narrow passages in the stump of a branch, indicating a previously unrecorded case of interspecific cohabitation [1, p. 32]. The record of Semonius glaucus from a single specimen in the collector’s garden was particularly significant, as the genus had previously been known only from the Kalahari Desert, making this the first record of the genus from the Malay region [1, p. 35].

The altitudinal gradient was evident in the results from Gunong Angsi. A few hours’ collecting on the slopes and in the neighbourhood of the bungalow at the summit produced forty-five different kinds of ants, twenty-five of which had not been found in Singapore [1, p. 26]. Overbeck noted that a closer survey of this locality should give very interesting results, a remark that remains unfulfilled in the Society’s literature [1, p. 26].

Behavioural Ecology and Symbiosis

The behavioural ecology of ants in the region was first systematically documented by H. N. Ridley in his 1890 note on the caringa (Formica gracilipes, Gray), which he described as the first account of the species’ method of constructing leaf nests [2, pp. 345–346]. Ridley observed that the ants select leaves from trees infested with scale insects—their primary food source—draw the leaf edges together using their hooked hind claws, sometimes forming chains of ants to bridge gaps, and then sew the leaves shut with silk produced by larvae carried to the work site [2, pp. 345–346]. He recorded a repair of a damaged nest on a Diospyros discolor tree, noting that the work was completed in under a quarter of an hour [2, pp. 345–346].

Ridley also documented the ants’ combat behaviour, describing a battle between caringas and a larger species of black ant on a fig tree, in which a single caringa that had lost a leg and its abdomen still repelled three opponents before retreating [2, pp. 346–347]. The species was noted to be cannibalistic, to feed on scale insect honey until nearly transparent, and to share this honey with nest-mates by regurgitation [2, pp. 346–347].

The larval silk-spinning behaviour was subsequently reviewed by R. S. Shelford in 1906, who described the well-documented habit of Oecophylla smaragdina, in which worker ants hold separated leaf edges together with their mandibles while other workers carry larvae whose silk filaments are drawn back and forth to weave a repair web across the breach [3, p. 284]. Shelford noted that the same habit had been recorded for Oecophylla longinoda of the Upper Congo and Camponotus senex of Brazil [3, p. 285]. He then drew attention to observations by Edu. Jacobson at Semarang, Java, on Polyrhachis dives, whose nest is constructed between the leaves of a Japanese palm and lined with silk partitions; Jacobson observed the same larval-spinning repair method when the nest was broken, suggesting that this behaviour may be more widespread among silk-using Polyrhachis species than previously suspected [3, p. 285].

Overbeck’s 1924 catalogue provided further evidence of ant–plant–insect symbiosis. Cremastogaster (Decacrema) borneensis was found in the hollow shafts at the end of the branches of a large tree-like Macaranga at Mandai Road, and in the hollow internodes of Macaranga hypoleuca from Bukit Timah Hill and the slopes of Gunong Angsi [1, p. 31]. Mr. Burkill found in the hollow shafts of a Macaranga inhabited by ants some Coccidae scale insects, the size of which showed that they had probably been brought in by the ants when quite young [1, p. 31]. Overbeck noted that in the same kind of Macaranga from Bukit Timah and Gunong Angsi the same kind of ant had been found, whilst another kind of Macaranga was inhabited by another kind of ant, and he referred readers to H. N. Ridley’s earlier work on the symbiosis of ants and plants [1, p. 31].

Additional symbiotic and commensal relationships were recorded throughout the catalogue. Cremastogaster rogenhoferi was observed on a tree, visiting Coccidae [1, p. 30]. Cremastogaster artifex constructed fairly large pasteboard nests round branches of trees and shrubs to serve as colonies, and smaller ones on leaves to shelter Coccidae [1, p. 30]. Cremastogaster (Physocrema) inflatus was found to breed Coccidae in the fissures of the bark and underneath loose bark [1, p. 31]. Meranoplus bicolor was observed on the extra-floral nectaries of the spider-orchid and on Jambu-fruits lying on the ground [1, p. 31]. Monomorium floricola was similarly recorded on the extra-floral nectaries of the spider-orchid [1, p. 32].

Collecting Methods and Ecological Observations

Overbeck’s account of his collecting methods provides valuable insight into the ecological habits of the region’s ant fauna. The most successful method was that followed by Forel in the jungles of Columbia, namely searching for colonies in hollow places in plants and trees, in rotten tree-stumps and branches, in decaying wood, underneath loose bark, and in branches hollow or honey-combed by beetle-larvae and white ants [1, p. 26]. A hedge of small bamboo in the collector’s compound, cut down by the gardener at regular intervals, yielded by far the greatest number of colonies and kinds when the internodes were cut open and withered [1, p. 26]. Baiting with honey met with some difficulty in regularly collecting the ants attracted, while the sweeping of shrubs and trees with a butterfly-net gave sometimes good results but was rather painful owing to the startling of mosquitoes and wasps (penyengat) [1, p. 26]. Captures at the lamp during the evening gave good results throughout the year and yielded many kinds whose colonies could not be found [1, p. 26].

The cups of Nepenthes, or pitcher-plants, proved to be quaint but sometimes very productive places of collecting, where ants nearly always formed the greater part of the remains of insects contained [1, p. 26]. White-ant hills, which harbour many kinds of ants, were rare [1, p. 26]. The frequency with which ants were recorded from Nepenthes cups throughout the species list—Diacamma tritschleri, Pachycondyla tridentata, Sima rufonigra, Sima (Tetraponera) allaborans subsp. crassiuscula, Pheidole exasperata var. polita, Cremastogaster rogenhoferi, Cremastogaster artifex, Cremastogaster longipilosa, Cremastogaster millardi, Cremastogaster ferrarii, Dilobocondyla cataulacoidea var. fulva, Cataulacus praetextus var. sumatrensis, Iridomyrmex levigastus, Plagiolepis rothneyi subsp. splendida, Prenolepis jerdoni, Camponotus (Dinomyrmex) gigas, Camponotus (Colobopsis) pilosus, Camponotus (Colobopsis) badius, Polyrhachis (Myrmothrinax) textor, Polyrhachis (Myrma) pruinosa, Polyrhachis (Myrmhopla) tibialis—suggests that these pitcher-plants served as a significant source of ant specimens, particularly from Ayer Terjun [1, pp. 27–40].

The commensal status of Monomorium pharaonis (the pharaoh ant) was documented through its occurrence in withered bamboo, in houses, in an office between old letters, and on board a mail steamer, indicating its established presence as a cosmopolitan commensal [1, p. 32]. Iridomyrmex anceps was recorded in great numbers at night on a steamer in the Straits of Malacca, at a fair distance from the shore [1, p. 34].

Attempts at breeding ants in a kind of incubator made of plaster-of-Paris sometimes proved successful; Overbeck recorded that a queen of Camponotus (Myrmoturba) maculatus subsp. mitis var. fuscithorax caught at the lamp raised a first generation of workers in the incubator, and a queen of Camponotus (Colobopsis) vitreus raised six workers [1, pp. 37–38]. However, attempts to breed Euponera (Trachymesopus) darwini and Pseudolasius ludovici failed, and a two years’ search for a colony of the former species was unsuccessful [1, pp. 27–28].

Research and Documentation

The Society’s literature on ants spans a period of more than three decades, from Ridley’s 1890 note on the caringa to Overbeck’s 1924 taxonomic catalogue, with Shelford’s 1906 note on silk-weaving ants falling between them. The earliest contributions were behavioural in character: Ridley’s 1890 note on Formica gracilipes and his 1891 reference to the keringga established a foundation for understanding the ecology of the region’s most conspicuous arboreal ant [2], [4]. Shelford’s 1906 note extended this behavioural interest to a comparative framework, linking local observations to records from the Upper Congo and Brazil, and raising the question of how widespread larval silk-spinning might be among Polyrhachis species [3].

The shift to systematic taxonomic documentation came with Overbeck’s 1924 paper, which represented a fundamentally different approach: a comprehensive species list based on intensive fieldwork over twenty months, with the taxonomic descriptions and type specimens residing in the collection of H. Viehmeyer in Dresden [1, pp. 25–26]. Overbeck’s paper is thus a secondary abstract rather than a primary taxonomic treatment, and the full descriptions of the new taxa appear in Viehmeyer’s 1915 paper in the Archiv für Naturgeschichte [1, p. 25]. The work was interrupted by the outbreak of the First World War in 1914, which halted further collecting and breeding work, and the results published in 1924 therefore represent only a portion of what had been gathered [1, p. 25].

The records reveal a clear progression from behavioural observation to taxonomic enumeration, with the ecological and symbiotic dimensions of ant life in the region documented primarily through incidental observations within the taxonomic framework rather than through dedicated ecological studies. Overbeck’s remarks on the potential of Gunong Angsi as a collecting locality, and his references to Ridley’s earlier work on ant–plant symbiosis, indicate areas where further investigation was anticipated but not yet undertaken in the Society’s literature [1, pp. 26].

MBRAS Sources

References

  1. H. Overbeck (1924). Some ants from Singapore and neighbouring places JMBRAS 2(1): 25–40.
  2. H.N. Ridley (1890). On the habits of the caringa (Formica gracilipes, Gray JSBRAS 22: 345–347. Read on JSTOR
  3. R.S. Shelford (1906). Nesting of silk-weaving ants JSBRAS 45: 284–285.
  4. H.N. Ridley (1891). The keringga JSBRAS 23: 147.