Leptomyrmex fragilis

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Leptomyrmex fragilis
Leptomyrmex fragilis
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Dolichoderinae
Tribe: Leptomyrmecini
Genus: Leptomyrmex
Species: L. fragilis
Binomial name
Leptomyrmex fragilis
(Smith, F., 1859)

Leptomyrmex fragilis side view

Leptomyrmex fragilis top view

Specimen labels

Evolutionary Relationships

Leptomyrmex neotropicus (fossil only)

Leptomyrmex relictus


Leptomyrmex burwelli

Leptomyrmex dolichoscapus


Leptomyrmex mjobergi

Leptomyrmex varians

Leptomyrmex unicolor

Leptomyrmex flavitarsus

Leptomyrmex puberulus

Leptomyrmex darlingtoni

Leptomyrmex fragilis

Leptomyrmex niger

Leptomyrmex erythrocephalus

Leptomyrmex wiburdi

Leptomyrmex cnemidatus

Leptomyrmex nigriventris

Leptomyrmex tibialis

Leptomyrmex geniculatus

Leptomyrmex nigriceps

Leptomyrmex pallens

Leptomyrmex rufithorax

Leptomyrmex rufipes

Leptomyrmex rothneyi

Leptomyrmex ruficeps

Based on Barden et al., 2017. Note only selected Leptomyrmex species are included.

Leptomyrmex fragilis has been recorded in rainforest, including lowland secondary and primary rainforest, montane rainforest and native gardens. Nests occur in the soil and in logs.

At a Glance • Replete Workers  



L. fragilis is the most commonly encountered Leptomyrmex species in New Guinea. Distinctively slender (HW 0.94–1.05 mm; PW 0.85–0.96 mm; DPW 0.27–0.33 mm), yellow and virtually hairless, it is unlikely to be confused with the one other pale species found in New Guinea, Leptomyrmex puberulus, which is stout and hairy, notably on the pronotum, head and eyes. Closely related to L. fragilis is the entirely black Leptomyrmex melanoticus, which may be a melanic form of L. fragilis. Although no intermediate color forms are currently known, future collections may reveal these sister species to be mere color variants within a single species. (Lucky and Ward 2010)

Keys including this Species


Latitudinal Distribution Pattern

Latitudinal Range: -2.645666° to -9.766670227°.

Tropical South

Distribution based on Regional Taxon Lists

Indo-Australian Region: Indonesia (type locality), New Guinea.

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.







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

  • fragilis. Formica fragilis Smith, F. 1859a: 136 (w.) INDONESIA (Aru I.). Emery, 1897d: 571 (m.); Stitz, 1912: 507 (m.); Lucvky & Ward, 2010: 36 (ergatoid q.). Combination in Leptomyrmex: Emery, 1897d: 571. Senior synonym of gracillimus: Baroni Urbani & Wilson, 1987: 2; of femoratus, maculatus, wheeleri: Lucky & Ward, 2010: 34. See also: Wheeler, W.M. 1934c: 113.
  • femorata. Leptomyrmex fragilis var. femorata Santschi, 1932b: 17, fig. 3 (w.) NEW GUINEA. Subspecies of fragilis: Wheeler, W.M. 1934c: 113. Junior synonym of fragilis: Lucky & Ward, 2010: 34.
  • gracillimus. Leptomyrmex gracillimus Wheeler, W.M. 1934c: 115, fig. 16 (w.) NEW GUINEA. Junior synonym of fragilis: Baroni Urbani & Wilson, 1987: 2.
  • maculata. Leptomyrmex fragilis var. maculata Stitz, 1938: 108 (w.) NEW GUINEA. Junior synonym of fragilis: Lucky & Ward, 2010: 34.
  • wheeleri. Leptomyrmex wheeleri Donisthorpe, 1948d: 600 (w.m.) NEW GUINEA. Junior synonym of fragilis: Lucky & Ward, 2010: 34.

Type Material



Lucky and Ward (2010) – measurements (n = 10) HL 1.74–1.98, HW 0.94–1.05, MFC 0.17–0.21, IOD 0.53–0.64, SL 3.96–4.61, EL 0.34–0.40, WL 3.21–4.04, PW 0.85–0.96, DPW 0.27–0.33, HTL 4.41–5.02, HTWmin 0.11–0.15, HTWmax 0.16–0.21, CI 0.51–0.58, SI 3.92–4.73, OI 0.12–0.16, HTC 0.55–0.74.

Small, slender species (HW 0.94–1.05 mm; WL 3.21–4.04 mm) with elongate head (CI 0.51–0.58), excluding mandibles, nearly twice as long as broad, widest at eyes. Sides of head straight; gently tapering anteriorly, posteriorly narrowing abruptly to a conical neck-like constriction. Approximately 15 teeth and denticles interspersed on masticatory margin of mandible. Anterior clypeal margin weakly concave. Eyes positioned at midline of head, relatively small, round, hairless, not surpassing lateral margins of head. Antennae slender, not compressed, scapes surpassing posterior margin of head by 3/5 their length.

Pronotum slender, distinctly elongated anteriorly. Propodeum with dorsal face 1.5 times the length of declivitous face, both faces concave, and meeting at rounded angle. Petiolar node triangular in profile, dorsal face rounded and bearing a longitudinal impression. Ventral surface of petiole weakly concave. Gaster long and slender, legs very long and slender (HTL 4.41–5.02 mm), not compressed (HTC 0.55–0.74).

Surface very finely shagreened and shining. Pubescence yellow, moderately dense on head and gaster. Pilosity confined to clypeus, venter and gaster. Head, thorax and usually gaster rufotestaceous. Femora and tibiae ranging from pale to dark brown, tarsi white. While generally rufotestaceous throughout, some variants with dark spots laterally on the gaster, or with gaster entirely black.


Lucky and Ward (2010) – Head broader than in worker. Three ocelli deeply set into head in triangular formation, the anteriormost one largest, the posterior two smaller. Pronotum, mesonotum and propodeum voluminous, convex. The anterior portion of the mesonotum with a distinctly raised medial bump. Dorsal face of propodeum broadly convex. Petiole broader than high, with distinct medial impression. Gaster globose, larger than in worker. Scapes, femora and tibiae broad, distinctly robust.

Surface of body appearing velvety, shagreened. Queen coloration similar to that of worker; gaster may be unicolorous pale or portions may be black.


Lucky and Ward (2010) – measurements (n = 3) HL 1.41–1.58, HW 1.01–1.04, SL 0.34–0.39, EL 0.58–0.65, HTL 4.74–5.26, CI 0.64–0.73, SI 0.34–0.38, SI2 1.09–1.15.


  • Baroni Urbani, C.; Wilson, E. O. 1987. The fossil members of the ant tribe Leptomyrmecini (Hymenoptera: Formicidae). Psyche (Camb.) 94: 1-8 (page 2, Senior synonym of gracillimus)
  • Emery, C. 1897c. Formicidarum species novae vel minus cognitae in collectione Musaei Nationalis Hungarici quas in Nova-Guinea, colonia germanica, collegit L. Biró. Természetr. Füz. 20: 571-599 (page 571, male described)
  • Lucky, A. 2011. Molecular phylogeny and biogeography of the spider ants, genus Leptomyrmex Mayr (Hymenoptera: Formicidae). Molecular Phylogenetics and Evolution 59: 281-292.
  • Lucky, A. & Ward, P.S. 2010. Taxonomic revision of the ant genus Leptomyrmex Mayr. Zootaxa 2688: 1-67.
  • Smith, F. 1859a. Catalogue of hymenopterous insects collected by Mr. A. R. Wallace at the islands of Aru and Key. [part]. J. Proc. Linn. Soc. Lond. Zool. 3: 132-158 (page 136, worker described)
  • Stitz, H. 1912. Ameisen aus Ceram und Neu-Guinea. Sitzungsber. Ges. Naturforsch. Freunde Berl. 1912: 498-514 (page 507, Combination in Leptomyrmex)
  • Wheeler, W. M. 1934c. A second revision of the ants of the genus Leptomyrmex Mayr. Bulletin of the Museum of Comparative Zoology 77: 69-118 (page 113, see also)

References based on Global Ant Biodiversity Informatics

  • Baroni Urbani C. 1977. Katalog der Typen von Formicidae (Hymenoptera) der Sammlung des Naturhistorischen Museums Basel (2. Teil). Mitt. Entomol. Ges. Basel (n.s.) 27: 61-102.
  • CSIRO Collection
  • Donisthorpe H. 1948. A fourth instalment of the Ross Collection of ants from New Guinea. Annals and Magazine of Natural History (12)1: 131-143.
  • Donisthorpe H. 1948. A third instalment of the Ross Collection of ants from New Guinea. Annals and Magazine of Natural History (11)14: 589-604.
  • Donisthorpe, Horace. 1943. The Ants of Waigeu Island, North Dutch New Guinea. The Annals and Magazine of Natural History 11 (10): 433-475.
  • Emery C. 1911. Formicidae. Résultats de l'expédition scientifique néerlandaise à la Nouvelle-Guinée en 1903 sous les auspices de Arthur Wichmann. Nova Guinea 5: 531-539.
  • Emery C. 1911. Formicidae. Résultats de l'expédition scientifique néerlandaise à la Nouvelle-Guinée en 1907 et 1909 sous les auspices de Dr. H. A. Lorentz. Nova Guin. 9: 249-259
  • Emery C. 1913. Hymenoptera. Fam. Formicidae. Subfam. Dolichoderinae. Genera Insectorum 137: 1-50.
  • General D. M., and G. D. Alpert. 2012. A synoptic review of the ant genera (Hymenoptera, Formicidae) of the Philippines. Zookeys 200: 1-111.
  • Janda M., G. D. Alpert, M. L. Borowiec, E. P. Economo, P. Klimes, E. Sarnat, and S. O. Shattuck. 2011. Cheklist of ants described and recorded from New Guinea and associated islands. Available on http://www.newguineants.org/. Accessed on 24th Feb. 2011.
  • Karavaiev V. 1926. Ameisen aus dem Indo-Australischen Gebiet. Treubia 8: 413-445.
  • Klimes P., P. Fibich, C. Idigel, and M. Rimandai. 2015. Disentangling the diversity of arboreal ant communities in tropical forest trees. PLoS ONE 10(2): e0117853. doi:10.1371/journal.pone.0117853
  • Lucky A., E. Sarnat, and L. Alonso. 2011. Ants of the Muller Range, Papua New Guinea, Chapter 10. In Richards, S. J. and Gamui, B. G. (editors). 2013. Rapid Biological Assessments of the Nakanai Mountains and the upper Strickland Basin: surveying the biodiversity of Papua New Guinea’s sublime karst environments. RAP Bulletin of Biological Assessment 60. Conservation International. Arlington, VA.
  • Lucky A., L. E. Alonso, E. Sarnat, and J. Hulr. 2015. Ants and scolytine beetles. In: Richards, S.J. and N. Whitmore (editors) 2015. A rapid biodiversity assessment of Papua New Guinea's Hindenburg Wall region. Wildlife Conservation Society Papua New Guinea Program. Goroka, PNG.
  • Lucky A., and P. S. Ward. 2010. Taxonomic revision of the ant genus Leptomyrmex Mayr (Hymenoptera: Formicidae). Zootaxa 2688: 1-67.
  • Room P. M. 1975. Diversity and organization of the ground foraging ant faunas of forest, grassland and tree crops in Papua Nez Guinea. Aust. J. Zool. 23: 71-89.
  • Santschi F. 1932. Résultats scientifiques du voyage aux Indes orientales néerlandaises de LL. AA. RR. le Prince et la Princesse Léopold de Belgique. Hymenoptera. Formicidae. Mémoires du Musée Royal d'Histoire Naturelle de Belgique. (2)4: 11-29.
  • Shattuck S. O. 1994. Taxonomic catalog of the ant subfamilies Aneuretinae and Dolichoderinae (Hymenoptera: Formicidae). University of California Publications in Entomology 112: i-xix, 1-241.
  • Smith F. 1863. Catalogue of hymenopterous insects collected by Mr. A. R. Wallace in the islands of Mysol, Ceram, Waigiou, Bouru and Timor. Journal and Proceedings of the Linnean Society of London. Zoology 7: 6-48.
  • Snelling R. R. 1998. Insect Part 1: The social Hymenoptera. In Mack A. L. (Ed.) A Biological Assessment of the Lakekamu Basin, Papua New Guinea, RAP 9. 189 ppages
  • Snelling R. R. 2000. Ants of the Wapoga river area, Irian Jaya, Indonesia. In Mack, Andrew L. and Leeanne E. Alonso (eds.). 2000. A Biological Assessment of the Wapoga River Area of Northwestern Irian Jaya, Indonesia. RAP Bulletin of Biological Assessment 14, Conservation International, Washington, DC.
  • Stitz H. 1912. Ameisen aus Ceram und Neu-Guinea. Sitzungsberichte der Gesellschaft Naturforschender Freunde zu Berlin 1912: 498-514.
  • Stitz H. 1938. Neue Ameisen aus dem indo-malayischen Gebiet. Sitzungsber. Ges. Naturforsch. Freunde Berl. 1938: 99-122.
  • Viehmeyer H. 1912. Ameisen aus Deutsch Neuguinea gesammelt von Dr. O. Schlaginhaufen. Nebst einem Verzeichnisse der papuanischen Arten. Abhandlungen und Berichte des Königlichen Zoologischen und Anthropologische-Ethnographischen Museums zu Dresden 14: 1-26.
  • Viehmeyer H. 1914. Ameisen aus Perak, Bali und Ceram (Hym.) (Freiburger Molukken-Expedition), gesammelt von E. Streesemann. Entomologische Mitteilungen. Berlin-Dahlem 3: 112-116.
  • Viehmeyer H. 1914. Papuanische Ameisen. Deutsche Entomologische Zeitschrift 1914: 515-535.
  • Wheeler W. M. 1915. The Australian honey-ants of the genus Leptomyrmex Mayr. Proceedings of the American Academy of Arts and Sciences 51: 255-286.
  • Wheeler W. M. 1934. A second revision of the ants of the genus Leptomyrmex Mayr. Bulletin of the Museum of Comparative Zoology 77: 69-118.
  • Wilson E. O. 1959. Patchy distributions of ant species in New Guinea rain forests. Psyche (Cambridge) 65: 26-38.
  • Wilson E. O. 1959. Some ecological characteristics of ants in New Guinea rain forests. Ecology 40: 437-447.