Some ants from Singapore and neighbouring places
H. Overbeck’s 1924 catalogue documents the ant fauna of Singapore and neighbouring localities, based on fieldwork conducted between November 1912 and June 1914 for the Dresden specialist H. Viehmeyer. The paper, published in the Journal of the Malayan Branch of the Royal Asiatic Society, presents a species list of over 190 ant taxa drawn from twelve collecting sites across Singapore, the Riau Archipelago, Negri Sembilan, and Johore, and records the description of one new genus, one new subgenus, sixteen new species, thirteen new subspecies, and fifteen new varieties (p. 26).
Summary
Overbeck’s work was conceived as a systematic survey of the local ant fauna, combining colony-based collection with opportunistic methods. The primary collecting ground was a fifteen-acre garden at the seventh mile of Bukit Timah Road, planted with fruit trees, coconut palms, and rubber. The most productive technique, following Forel’s method from the Colombian jungles, involved searching for colonies in hollow plant structures, rotten stumps, decaying wood, and beneath loose bark. A hedge of small bamboo, cut down at regular intervals, proved exceptionally rich, as the cut and withered internodes harboured the greatest concentration of colonies. Supplementary methods included baiting with honey, sweeping shrubs with a butterfly-net, evening lamp captures, and the examination of Nepenthes pitcher-plant cups, which regularly contained ant remains (pp. 25–26).
The list is organised taxonomically by subfamily—Dorylinae, Ponerinae, Myrmicinae, Dolichoderinae, and Camponotidae—and for each taxon Overbeck records the sex of the specimens, the locality, and the microhabitat or collection method. Several entries note ecological observations of particular interest: the symbiotic relationship between Cremastogaster (Decacrema) borneensis and Macaranga trees, in which ants inhabit the hollow internodes and tend Coccidae scale insects; the polygynous colonies of Solenopsis overbecki with four wingless queens; and the co-occurrence of Monomorium floricola with a new subgenus hospitum in the same narrow passages (pp. 31–32). The Gunong Angsi expedition, though brief, yielded 45 ant species in a few hours, 25 of which were absent from Singapore, underscoring the faunal differentiation between lowland and montane habitats (p. 26).
Overbeck also attempted to breed ants in a plaster-of-Paris incubator, with partial success: Cremastogaster millardi produced first-generation workers on three occasions, and a single Camponotus (Colobopsis) vitreus queen raised six workers. These breeding records provided evidence that the first-generation workers found in hollow branches in the wild were indeed the product of a founding queen rather than a separate caste (pp. 30, 37).
Key Findings
- More than 300 glass tubes of specimens were sent to Viehmeyer in Dresden, yielding over 190 distinct ant taxa from the region (p. 26).
- New taxa described by Viehmeyer (1915) on the basis of Overbeck’s material include 1 genus (Overbeckia), 1 subgenus (Monomorium subg. hospitum), 16 species, 13 subspecies, and 15 varieties (p. 26).
- A few hours’ collecting on Gunong Angsi (2,700 ft., Negri Sembilan) produced 45 ant species, 25 of which had not been recorded from Singapore (p. 26).
- Cremastogaster (Decacrema) borneensis was found in the hollow shafts of Macaranga hypoleuca, with Coccidae scale insects present that Burkill judged to have been introduced by the ants as larvae, confirming the ant–plant–scale insect tripartite symbiosis first described by Ridley (1910) (p. 31).
- Semonius glaucus, a genus previously known only from the Kalahari Desert, was recorded for the first time from the Malay region, represented by a single specimen from the garden (p. 35).
- Monomorium pharaonis (the pharaoh ant) was found in withered bamboo, in houses, in an office between old letters, and on board a mail steamer, indicating its established status as a cosmopolitan commensal (p. 32).
Conclusion
Overbeck’s catalogue establishes the first comprehensive inventory of the ant fauna of Singapore and its immediate surroundings, demonstrating that the island supports a rich and taxonomically diverse assemblage with significant endemism. The work also highlights the faunal contrast between lowland Singapore and the montane forests of Gunong Angsi, and provides early field evidence for ant–plant mutualisms that would later become a major research theme in tropical ecology.
Context
- Overbeck was a private collector working under the direction of the Dresden myrmecologist H. Viehmeyer; the full taxonomic descriptions and type specimens reside in Viehmeyer’s collection, making this paper a secondary abstract rather than a primary taxonomic treatment (p. 25).
- The study was interrupted by the outbreak of the First World War in 1914, which halted further collecting and breeding work (p. 25).