Ectomomyrmex

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Ectomomyrmex
Ectomomyrmex javanus
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Ponerinae
Tribe: Ponerini
Alliance: Ponera genus group
Genus: Ectomomyrmex
Mayr, 1867
Type species
Ectomomyrmex javanus

Pachycondyla javana casent0217561 p 1 high.jpg

Pachycondyla javana casent0217561 d 1 high.jpg

Specimen Labels

Diversity
31 species
(Species Checklist, Species by Country)

Ectomomyrmex is restricted to Asia and Australia. They are apparently epigeic generalist predators. Colonies of Ectomomyrmex leeuwenhoeki are very small (< 10 workers) and monogynous, with either a dealated queen (7 colonies) or a gamergate (8 colonies) (Ito et al. 2007).

Identification

Schmidt and Shattuck (2014) - Ectomomyrmex workers can be identified by the following combination of characters: head, mesosoma and petiole strongly sculptured, head usually prismatic posteriorly, mesopleuron divided by a transverse groove, and petiole with a sweeping posterior face. Ectomomyrmex workers are similar to those of some Ponera species (e.g., Ponera alpha), but Ectomomyrmex workers lack an anterior fenestra in the subpetiolar process and have two metatibial spurs and a divided mesopleuron. Ectomomyrmex is also superficially similar to Pachycondyla, but Ectomomyrmex lacks the complex metapleural gland orifice and hypopygial spines of Pachycondyla, and Pachycondyla lacks the prismatic head shape of Ectomomyrmex. Ectomomyrmex is also somewhat similar to Cryptopone and Pseudoponera, but differs from them in having strong sculpturing, larger eyes, no basal mandibular pit, a prismatic head, divided mesopleuron, slit-shaped propodeal spiracles, a sweeping posterior petiolar face, and no traction setae on the mesotibiae. Ectomomyrmex may be confused with Pseudoneoponera or Bothroponera, but Ectomomyrmex lacks the shaggy pilosity and longitudinally striate tergite A3 of Pseudoneoponera, and the large eyes, undivided mesopleuron, and block-like petiole of Bothroponera.

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Keys including this Genus

 

Keys to Species in this Genus

Distribution

Ectomomyrmex ranges across most of the Indo-Australian and Australasian regions, from India east to Japan and from northwestern China south to northern Australia (Brown, 1963).

Distribution and Richness based on AntMaps

Species by Region

Number of species within biogeographic regions, along with the total number of species for each region.

Afrotropical Region Australasian Region Indo-Australian Region Malagasy Region Nearctic Region Neotropical Region Oriental Region Palaearctic Region
Species 0 2 23 0 0 0 11 6
Total Species 2841 1736 3045 932 835 4379 1741 2862

Biology

Schmidt and Shattuck (2014) - Very little is known about the habits of Ectomomyrmex. Anecdotal observations, and the moderately small eyes of Ectomomyrmex workers, suggest that their foraging habits are somewhat intermediate between epigeic and hypogeic. They are apparently generalist arthropod predators (Wilson, 1958c, 1959a), and Ke et al. (2008) observed that workers of Ectomomyrmex astutus were particularly fierce predators of termites in an artificial arena. Wilson (1958c) observed Ectomomyrmex aciculatus foraging diurnally on the forest floor among and under leaf litter, observed Ectomomyrmex exaratus foraging on the forest floor, and reported that E. striatulus forms small colonies (fewer than 100 workers) and nests in rotting logs. Like its close relatives Ponera and Cryptopone, workers of Ectomomyrmex apparently feign death when disturbed (Wilson, 1958c).

Life History Traits

  • Mean colony size: <100 (Greer et al., 2021)
  • Compound colony type: not parasitic (Greer et al., 2021)
  • Nest site: hypogaeic (Greer et al., 2021)
  • Diet class: predator (Greer et al., 2021)
  • Foraging stratum: subterranean/leaf litter (Greer et al., 2021)

Castes

Morphology

Worker Morphology

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 • Eyes: 11-100 ommatidia • Pronotal Spines: absent • Mesonotal Spines: absent • Propodeal Spines: absent • Petiolar Spines: absent • Caste: none or weak • Sting: present • Metaplural Gland: present • Cocoon: present

Karyotype

Species Uncertain

  • n = 19, 2n = 38, karyotype = 16M+22A (India) (Imai et al., 1984; Mariano et al., 2015).

All Karyotype Records for Genus

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Taxon Haploid Diploid Karyotype Locality Source Notes
Ectomomyrmex 19 38 16M+22A India Imai et al., 1984; Mariano et al., 2015
Ectomomyrmex astutus 11 22 Indonesia Imai et al., 1985; Mariano et al., 2015 as ''Pachycondyla astuta''
Ectomomyrmex astutus 9 18 Indonesia Imai et al., 1985; Mariano et al., 2015 as ''Pachycondyla astuta''

Phylogeny

Ponerinae

Platythyrea  (40 species, 6 fossil species)

Pachycondyla group
⊞(show genera)
⊟
Ponera group
⊞(show genera)
⊟

Harpegnathos  (13 species, 0 fossil species)

Hypoponera  (177 species, 1 fossil species)

Plectroctena group
⊞(show genera)
⊟
Odontomachus group
⊞(show taxa)
⊟

See Phylogeny of Ponerinae for details.

Nomenclature

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

  • ECTOMOMYRMEX [Ponerinae: Ponerini]
    • Ectomomyrmex Mayr, 1867a: 83. Type-species: Ectomomyrmex javanus, by subsequent designation of Bingham, 1903: 85.
    • Ectomomyrmex as subgenus of Pachycondyla: Emery, 1901a: 42; Emery, 1911d: 78; Forel, 1917: 237.
    • Ectomomyrmex as genus: Bingham, 1903: 85; Wheeler, W.M. 1922a: 648; Brown, 1963: 9; Taylor, 1987a: 26.
    • Ectomomyrmex junior synonym of Pachycondyla: Snelling, R.R. 1981: 389; Hölldobler & Wilson, 1990: 11; Brown, in Bolton, 1994: 164.
    • Ectomomyrmex revived from synonymy: Schmidt & Shattuck, 2014: 191.
    • [Ectomyrmex: incorrect subsequent spelling by Donisthorpe, 1943f: 641.]

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

Description

Schmidt and Shattuck (2014):

Worker

Medium to large (TL 5–12.8 mm) ants with the standard characters of Ponerini. Mandibles triangular, with up to 10 teeth on the masticatory margin and often a faint basal groove. Anterior clypeal margin convex, sometimes medially emarginate. Frontal lobes small to moderate in size. Eyes very small to small, located anterior of head midline. Head usually prismatic posteriorly, with distinct angular ridges between dorsal and lateral surfaces. Mesopleuron divided by a transverse groove. Metanotal groove obsolete or reduced to a simple suture. Propodeum broad to narrowed dorsally, with sharp posterior margins. Propodeal spiracles slit-shaped. Metapleural gland orifice sometimes with a posterior flange. Metatibial spur formula (1s, 1p). Petiole squamiform to nodiform, the scale usually much wider than long, in dorsal view with a convex anterior face and in lateral view a forward-sweeping posterior face. Gaster with a moderate girdling constriction between pre- and postsclerites of A4. Head, mesosoma and petiole deeply striate, rugoreticulate or punctate, the gaster usually finely punctate but sometimes striate (e.g. in Ectomomyrmex acutus). Head and body with abundant short pilosity and light to dense pubescence. Color black.

Queen

Similar to worker but slightly larger, winged, with ocelli, larger compound eyes, and the usual modifications of the thoracic sclerites (Ogata, 1987).

Male

See description by Ogata (1987).

References

  • Arnold, G. 1915. A monograph of the Formicidae of South Africa. Part I. Ponerinae, Dorylinae. Ann. S. Afr. Mus. 14: 1-159 (page 53, Ectomomyrmex as subgenus of Pachycondyla)
  • Ashmead, W. H. 1905c. A skeleton of a new arrangement of the families, subfamilies, tribes and genera of the ants, or the superfamily Formicoidea. Can. Entomol. 37: 381-384 (page 382, Ectomomyrmex in Pachycondylinae, Pachycondylini; Ectomomyrmex as genus)
  • Bingham, C. T. 1903. The fauna of British India, including Ceylon and Burma. Hymenoptera, Vol. II. Ants and Cuckoo-wasps. London: Taylor and Francis, 506 pp. (page 85, Type-species: Ectomomyrmex javanus; by subsequent designation; Ectomomyrmex as genus)
  • Bolton, B. 1994. Identification guide to the ant genera of the world. Cambridge, Mass.: Harvard University Press, 222 pp. (page 164, Ectomomyrmex as junior synonym of Pachycondyla)
  • Bolton, B. 2003. Synopsis and Classification of Formicidae. Mem. Am. Entomol. Inst. 71: 370pp (page 166, Ectomomyrmex as junior synonym of Pachycondyla [Ectomomyrmex is sometimes misspelled Ectomyrmex, for example Donisthorpe, 1943f: 641.])
  • Brown, W. L., Jr. 1963a. Characters and synonymies among the genera of ants. Part III. Some members of the tribe Ponerini (Ponerinae, Formicidae). Breviora 190: 1-10 (page 9, Ectomomyrmex as genus)
  • Brown, W. L., Jr. 1973b. A comparison of the Hylean and Congo-West African rain forest ant faunas. Pp. 161-185 in: Meggers, B. J., Ayensu, E. S., Duckworth, W. D. (eds.) Tropical forest ecosystems in Africa and South America: a comparative review. Wash (page 180, Ectomomyrmex as junior synonym of Pachycondyla (provisional))
  • Burchill, A.T., Moreau, C.S. 2016. Colony size evolution in ants: macroevolutionary trends. Insectes Sociaux 63, 291–298 (doi:10.1007/s00040-016-0465-3).
  • Cantone S. 2018. Winged Ants, The queen. Dichotomous key to genera of winged female ants in the World. The Wings of Ants: morphological and systematic relationships (self-published).
  • Chapman, J. W.; Capco, S. R. 1951. Check list of the ants (Hymenoptera: Formicidae) of Asia. Monogr. Inst. Sci. Technol. Manila 1: 1-327 (page 60, Ectomomyrmex as genus)
  • Dalla Torre, K. W. von. 1893. Catalogus Hymenopterorum hucusque descriptorum systematicus et synonymicus. Vol. 7. Formicidae (Heterogyna). Leipzig: W. Engelmann, 289 pp. (page 30, Ectomomyrmex in Ponerinae; Ectomomyrmex as genus)
  • Emery, C. 1895l. Die Gattung Dorylus Fab. und die systematische Eintheilung der Formiciden. Zool. Jahrb. Abt. Syst. Geogr. Biol. Tiere 8: 685-778 (page 767, Ectomomyrmex in Ponerinae, Ponerini)
  • Emery, C. 1901b. Notes sur les sous-familles des Dorylines et Ponérines (Famille des Formicides). Ann. Soc. Entomol. Belg. 45: 32-54 (page 42, Ectomomyrmex as subgenus of Pachycondyla)
  • Emery, C. 1911e. Hymenoptera. Fam. Formicidae. Subfam. Ponerinae. Genera Insectorum 118: 1-125 (page 78, Ectomomyrmex in Ponerinae, Ponerini [subtribe Pachycondylini]; Ectomomyrmex as subgenus of Pachycondyla)
  • Esteves, F.A., Fisher, B.L. 2021. Corrieopone nouragues gen. nov., sp. nov., a new Ponerinae from French Guiana (Hymenoptera, Formicidae). ZooKeys 1074, 83–173 (doi:10.3897/zookeys.1074.75551).
  • Forel, A. 1900f. Les Formicides de l'Empire des Indes et de Ceylan. Part VII. J. Bombay Nat. Hist. Soc. 13: 303-332 (page 321, Ectomomyrmex in Ponerinae, Ponerini; Ectomomyrmex as genus)
  • Forel, A. 1917. Cadre synoptique actuel de la faune universelle des fourmis. Bull. Soc. Vaudoise Sci. Nat. 51: 229-253 (page 237, Ectomomyrmex as subgenus of Pachycondyla)
  • Hölldobler, B.; Wilson, E. O. 1990. The ants. Cambridge, Mass.: Harvard University Press, xii + 732 pp. (page 11, Ectomomyrmex as junior synonym of Pachycondyla)
  • Mariano, C.S.F., Santos, I.S., Silva, J.G., Costa, M.A., Pompolo, S.G. 2015. Citogenética e evolução do cariótipo em formigas poneromorfas. In: Delabie, J.H.C., Feitosa, R.M., Serrao, J.E., Mariano, C.S.F., Majer, J.D. (eds) As formigas poneromorfas do Brasil, 1st edn. Ilhéus, Brasil, pp 102–125 (doi:10.7476/9788574554419.0010).
  • Mayr, G. 1867a. Adnotationes in monographiam formicidarum Indo-Neerlandicarum. Tijdschr. Entomol. 10: 33-117 (page 83, Ectomomyrmex as genus)
  • Ogata, K. 1987a. A generic synopsis of the poneroid complex of the family Formicidae in Japan (Hymenoptera). Part 1. Subfamilies Ponerinae and Cerapachyinae. Esakia 25: 97-132 (page 112, Ectomomyrmex as genus)
  • Schmidt, C.A. & Shattuck, S.O. 2014. The higher classification of the ant subfamily Ponerinae (Hymenoptera: Formicidae), with a review of ponerine ecology and behavior. Zootaxa 3817, 1–242 (doi:10.11646/zootaxa.3817.1.1).
  • Snelling, R. R. 1981. Systematics of social Hymenoptera. Pp. 369-453 in: Hermann, H. R. (ed.) Social insects. Volume 2. New York: Academic Press, xiii + 491 pp. (page 389, Ectomomyrmex as junior synonym of Pachycondyla)
  • Taylor, R. W. 1987a. A checklist of the ants of Australia, New Caledonia and New Zealand (Hymenoptera: Formicidae). CSIRO Div. Entomol. Rep. 41: 1-92 (page 26, Ectomomyrmex as genus)
  • Taylor, R. W.; Brown, D. R. 1985. Formicoidea. Zool. Cat. Aust. 2:1- 149: 1-149, 30 (page 29, Ectomomyrmex as genus)
  • Wheeler, W. M. 1910b. Ants: their structure, development and behavior. New York: Columbia University Press, xxv + 663 pp. (page 135, Ectomomyrmex as subgenus of Pachycondyla)
  • Wheeler, W. M. 1922i. Ants of the American Museum Congo expedition. A contribution to the myrmecology of Africa. VII. Keys to the genera and subgenera of ants. Bull. Am. Mus. Nat. Hist. 45: 631-710 (page 648, Ectomomyrmex in Ponerinae, Ponerini; Ectomomyrmex as genus)
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