Polyrhachis ypsilon

AntWiki: The Ants --- Online
Jump to navigation Jump to search
Polyrhachis ypsilon
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Formicinae
Tribe: Camponotini
Genus: Polyrhachis
Subgenus: Polyrhachis
Species group: bihamata
Species: P. ypsilon
Binomial name
Polyrhachis ypsilon
Emery, 1887

Polyrhachis ypsilon 1 side.jpg

Polyrhachis ypsilon 1 top.jpg

Specimen labels 1

Specimen labels 2


Collected from various forest habitats.


A member of the bihamata group of the subgenus Polyrhachis. Kohout (2014) - Polyrhachis ypsilon is easily recognised by its large size, rather massive pronotal spines, petiolar spines that widely diverge from their bases and the abundant hairs and rich golden pubescence covering the body. Morphologically it is a relatively stable species with specimens from throughout its range being closely similar.

Keys including this Species


Polyrhachis ypsilon is known from peninsular Malaysia, Singapore, Borneo and Sumatra. (Kohout, 2014)

Latitudinal Distribution Pattern

Latitudinal Range: 6.088055556° to -4.558585°.

Tropical South

Distribution based on Regional Taxon Lists

Indo-Australian Region: Borneo, Brunei Darussalam, Indonesia, Malaysia, Singapore (type locality).

Distribution based on AntMaps


Distribution based on AntWeb specimens

Check data from AntWeb

Countries Occupied

Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species.


Estimated Abundance

Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species.




Male and immature stages unknown.


The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

  • ypsilon. Polyrhachis ypsilon Emery, 1887a: 239 (w.) SINGAPORE. Wheeler, G.C. & Wheeler, J. 1990b: 764 (l.). Senior synonym of synacantha, victoris: Hung, 1970: 19.
  • victoris. Polyrhachis ypsilon var. victoris Santschi, 1925f: 93 (w.) INDONESIA (Sumatra). (Misspelled as vecticortis by Chapman & Capco, 1951: 304.) Junior synonym of ypsilon: Hung, 1970: 19.
  • synacantha. Polyrhachis (Polyrhachis) ypsilon ab. synacantha Santschi, 1933d: 2 (w.) BORNEO. Junior synonym of ypsilon: Hung, 1970: 19.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Two subspecific forms have been described, P. ypsilon var. victoris Santschi from Sumatra and P. ypsilon ab. synacantha from Borneo, by Santschi in 1925 and 1933 respectively. Both were synonymised with the nominal form by Hung (1970: 20), who considered the former to be a geographical variant while he was unable to locate the type of the latter. I have previously examined the unique holotype of P. ypsilon ab. synacantha in the collection of Prince Léopold (IRSN). Based on its extremely aberrant petiolar node, a huge, pillar-like structure terminating dorsolaterally in rather asymmetrical, dentiform angles, bearing two minute, posteriorly directed, uneven, acute spines, I considered it an undoubtedly anomalous variant (Kohout 1998: 509) and concurred with Hung’s (1970) opinion that it is a synonym of P. ypsilon. (Kohout, 2014)



Hung (1970) - Lectotype (herein-designated from a syntype in the collection of Museo Civico di Storia Naturale). HW 2.62 mm, HL 3.00 mm, CI 87, SL 3.90 mm, SI 149, PW 1.60 mm, MPL 3.07 mm, MTL 5.40 mm, PSEI 150, PH 3.17 mm. Clypeus convex, slightly carinated. Median ocellus present, no lateral ocelli. Alitrunk rounded. Pronotum somewhat flat on top, but no traces of margins present. Pronotal spines very-stout, pointing outwards and slightly backwards, black throughout the whole length. Mesonotal spines less pyramidal than in Polyrhachis bihamata, rising upwards and bent backwards, parallel when viewed from top. Metanotal groove present. Propodeum with two contiguous ridges between basal face and the declivity. The basal face is about twice as long as the declivity. The face of the declivity fiat and slightly margined along the sides. Mesonotal spines only the distal half black. Petiole columnar, with two long, hook-shaped spines diverging widely from their base, with left hook slightly longer than right hook. Body densely covered with hairs. Antennae and legs black. Alitrunk dark reddish-brown. Gaster reddish-black.

Kohout (2014) - Dimensions (lectotype cited first): TL c. 12.85, 12.10 – 13.10; HL 2.97, 2.67 – 2.97; HW 2.57, 2.32 – 2.68; CI 86, 86 – 93; SL 3.83, 3.43 – 3.93; SI 149, 139 – 150; PW 1.71, 1.40 – 1.71; PeH 3.07, 3.02 – 3.61; PeI 103, 103 – 124; MTL 5.44, 4.74 – 5.44 (1+15 measured).

Dimensions (holotype of synacantha): TL c. 13.71; HL 3.02; HW 2.67; CI 88; SL 3.93; SI 147; PW 1.71; PeH 3.83; PeI 129; MTL 5.39 (1 measured).

Dimensions (syntypes of victoris): TL c. 12.65 – 12.75; HL 2.84 – 2.90; HW 2.53-2.60; CI 89 – 90; SL 3.63 – 3.73; SI 143 – 144; PW 1.31 – 1.41; PeH 3.43 – 3.58; PeI 119 – 123; MTL 4.84 – 5.04 (3 measured).


Kohout (2014) - Dimensions: TL c. 13.25 – 14.82; HL 2.82 – 3.22; HW 2.42 – 2.82; CI 86 – 87; SL 3.78 – 4.23; SI 150 – 156; PW 2.87 – 3.12; PeH 1.31 – 1.56; PeI 46 – 48; MTL 4.79 – 5.44 (2 measured).

Queen larger than worker and with usual characters identifying full sexuality, including three ocelli, complete thoracic structure and wings. Mandibles with four teeth; apical tooth much longer than other teeth which are greatly reduced or often vestigal. Eyes only moderately larger than in worker; sides of head in front of eyes virtually parallel towards mandibular bases. Frontal triangle distinct; frontal carinae sinuate with distinctly raised margins; central area concave with frontal furrow almost reaching median ocellus. Pronotal spines reduced to blunt angles. Mesoscutum wider than long; lateral margins converging anteriorly into moderately rounded anterior margin; median line distinct; parapsides flat; mesoscutum in profile relatively high, with anterior face widely rounding onto moderately convex, relatively short dorsum. Mesoscutellum moderately convex, only marginally elevated above dorsal plane of mesosoma. Propodeal dorsum not marginate, convex in outline, longer than declivity; posterior angles only poorly raised as medially directed, blunt ridges with propodeal dorsum between them descending into declivity in medially uninterrupted line. Petiole with pair of basally stout, relatively short, widely diverging spines with extreme tips curved backwards.

Mandibles finely longitudinally striate with piliferous pits. Head, mesosoma and petiole very finely reticulate-punctate; sides of mesosoma and coxae distinctly more coarsely sculptured; extreme tips of petiolar spines smooth and polished. Gaster shagreened.

Mandibles at masticatory borders with several curved golden hairs. Anterior clypeal margin with numerous, rather long setae medially and fringe of marginally shorter setae laterally. Generally abundant, relatively long, golden hairs on all dorsal body surfaces, including appendages, some hairs almost as long as greatest diameter of eyes. Closely appressed, rather long, rich golden pubescence in various densities over most body surfaces; pubescence somewhat longer on sides of head and mesosoma and virtually absent from tips of petiolar spines.

Colour. Black, with only base of petiole, subpetiolar process and most of first gastral tergite medium reddish-brown.

Type Material

Kohout (2014) - Syntype workers (lectotype and paralectotypes designated by Hung, 1970: 19). Type locality: SINGAPORE (L.M. D’Albertis), Museo Civico di Storia Naturale, Genoa (examined).


References based on Global Ant Biodiversity Informatics

  • Bluthgen N., D. Mezger, and K.E. Linsenmair. 2006. Ant-hemipteran trophobioses in a Bornean rainforest- diversity, specificity and monopolisation. Insectes Sociaux 53: 194-203.
  • Chapman, J. W., and Capco, S. R. 1951. Check list of the ants (Hymenoptera: Formicidae) of Asia. Monogr. Inst. Sci. Technol. Manila 1: 1-327
  • Chung A.Y.C., and M. Mohamed. 1996. A comparative study of the ant fauna in a primary and secondary forest in Sabah, Malaysia. In Edwards, D.S. Booth, W.E. and S.C. Choy (eds). Tropical Rainforest Research. Kluwer Academic Publishers. Pp 357-366.
  • Crawley W.C. 1924. Ants from Sumatra, with biological notes by Edward Jacobson. Annals and Magazine of Natural History (9)13: 380-409
  • Davidson D. W., S. C. Cook, R. R. Snelling and T. H. Chua. 2003. Explaining the Abundance of Ants in Lowland Tropical Rainforest Canopies. Science 300: 969-972.
  • Davidson, D.W., J.-P. Lessard, C.R. Bernau and S.C. Cook. 2007. The Tropical Ant Mosaic in a Primary Bornean Rain Forest. Biotropica 39(4):468-475
  • Emery C. 1886. Saggio di un catalogo sistematico dei generi Camponotus, Polyrhachis e affini. Memorie della Reale Accademia delle Scienze dell'Istituto di Bologna 5: 363-382
  • Emery C. 1893. Formicides de l'Archipel Malais. Revue Suisse de Zoologie 1: 187-229.
  • Emery, C. "Catalogo delle formiche esistenti nelle collezioni del Museo Civico di Genova. Parte terza. Formiche della regione Indo-Malese e dell'Australia." Annali del Museo Civico di Storia Naturale Giacomo Doria (Genova) (2) 4, no. 24 (1887): 209-258.
  • Emery, C. "Formiche raccolte da Elio Modigliani in Sumatra, Engano e Mentawei." Annali del Museo Civico di Storia Naturale Giacomo Doria (Genova) (2) 20, no. 40 (1900): 661-722.
  • Emery, C. "Voyage de MM. Bedot et Pictet dans l'Archipel Malais. Formicides de l'Archipel Malais." Revue Suisse de Zoologie 1 (1893): 187-229.
  • Floren A., W. Wetzel, and M. Staab. 2013. The contribution of canopy species to overall ant diversity (Hymenoptera: Formicidae) in temperate and tropical ecosystems. – Myrmecological News 19: 65-74.
  • Forel A. 1893. Les Formicides de l'Empire des Indes et de Ceylan. Part III. J. Bombay Nat. Hist. Soc. 8: 17-36.
  • Hashimoto Y., Y. Morimoto, E. S. Widodo, and M. Mohamed. 2006. Vertical distribution pattern of ants in a Bornean tropical rainforest (Hymenoptera: Formicidae). Sociobiology 47(3): 697- 710.
  • Hung A. C. F. 1970. A revision of ants of the subgenus Polyrhachis Fr. Smith (Hymenoptera: Formicidae: Formicinae). Oriental Insects 4(1): 1-36.
  • Kohout R. J. 1998. New synonyms and nomenclatural changes in the ant genus Polyrhachis Fr. Smith (Hymenoptera: Formicidae: Formicinae). Memoirs of the Queensland Museum 42: 505-531
  • Kohout R. J. 2014. A review of the subgenus Polyrhachis (Polyrhachis) Fr. Smith (Hymenoptera: Formicidae: Formicinae) with keys and description of a new species. Asian Myrmecology 6: 1-31.
  • Mezger D., and N. Bluthgen. 2007. Trophobioses on Borneo climbing bamboo - diversity and ecology of ant-hemipteran associations on Dinochloa trichogona (Poaceae). Asian Myrmecology 1: 59-68.
  • Mohamed M. 1995. A preliminary list of ants (Hymenoptera: Formicidae) of the Tawau Hills Park, Sabah. In: Ghazally Ismail et al. (eds.), Tawau Hills Park, Sabah, Pelanduk Pub. Pp. 205-213.
  • Pfeiffer M.; Mezger, D.; Hosoishi, S.; Bakhtiar, E. Y.; Kohout, R. J. 2011. The Formicidae of Borneo (Insecta: Hymenoptera): a preliminary species list. Asian Myrmecology 4:9-58
  • Robson Simon Ant Collection, 05-Sept-2014
  • Robson Simon Database Polyrhachis -05 Sept 2014
  • Santschi F. 1925. Contribution à la faune myrmécologique de la Chine. Bulletin de la Société Vaudoise des Sciences Naturelles 56: 81-96.
  • Santschi F. 1933. Formicides des collections de S. A. R. le Prince Léopold de Belgique. Voyage aux Indes orientales, 1932. Bulletin du Musée Royal d'Histoire Naturelle de Belgique. 9(27): 1-3.
  • Sukimin S., M. Mohamed, and H. Aris. 2010. Ant diversity of Maliau Basin Conservation Area, Sabah, Malaysia. Journal of Tropical Biology and Conservation 6:89-101.
  • Viehmeyer H. 1916. Ameisen von den Philippinen und anderer Herkunft (Hym.). Entomologische Mitteilungen. Berlin-Dahlem 5: 283-291.
  • Wheeler W. M. 1919. The ants of Borneo. Bulletin of the Museum of Comparative Zoology 63:43-147.
  • Yusah K. M., T. M. Fayle, G. Harris, and W. A. Foster. 2012. Optimizing diversity assesment protocols for high canopy ants in tropical rain forest. Biotropica 44(1): 73-81.