Diacamma scalpratum

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Diacamma scalpratum
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Ponerinae
Tribe: Ponerini
Genus: Diacamma
Species: D. scalpratum
Binomial name
Diacamma scalpratum
(Smith, F., 1858)

Diacamma scalpratum casent0173639 profile 1.jpg

Diacamma scalpratum casent0173639 dorsal 1.jpg

Specimen labels


Peeters, Heraty & Wiwatwitaya (2015) excavated four complete colonies of D. scalpratum from northern Thailand. Colonies were plentiful and easy to find in a small patch of pine forest. Excavation continued to a depth of 90cm in one colony. These four colonies yielded 151±109 workers (mean number ±SD) and 69±38 cocoons (range 47-101). Only one worker had gemmae in each colony, and dissections confirmed that this was the gamergate (i.e. mated and egg-laying). All workers dissected had 16-20 ovarioles, and this number is diagnostic among closely related species (e.g. another species with large workers from Thailand has 8 ovarioles).

At a Glance • Gamergate  

Photo Gallery

  • Diacamma scalpratum nest, northern Thailand. Photo by Pete Williams.
  • Diacamma scalpratum nest, northern Thailand. Photo by Pete Williams.


Laciny et al. (2015) - Very large, slender species (TL ca. 16.4–18.5 mm). Trunk black; frontal lobes and clypeus often, subpetiolar process and gaster tergites and sternites at posterior margins always reddish brown; mandibles and tibiae dark reddish brown. Standing setae on trunk short. Trunk strongly striate on mesosoma and petiole, weaker on head. Head, mesosoma, and petiole with very dense microreticulation, matt. Head elongated, sides posteriorly of eye moderately convex. Striation posterior of eyes meeting narrow, slightly concave occipital margin; ridges slightly narrower than interspaces; occipital margin laterally slightly widened and terminating in very short, blunt projections. Eyes small, not protruding. Clypeus finely, very densely punctured, except for anterior margin with larger and sparser puncturation; anteromedially with widely rounded apex. Striae on pronotum transversely elliptical. Striation on mesosoma sides slightly oblique, upcurved on propodeum. Petiole strongly compressed, dorsally not striate, but with crest posteriorly forked up to the closely spaced, long teeth; dorsolaterally with striation oblique relative to dorsal outline of node, ventrolaterally with reduced striation and almost smooth; subpetiolar process prominent, strongly concave, posterior corner longer than anterior one. Gaster tergite 1 without striation, but with fine puncturation, shiny as the following tergites.

As in the Diacamma intricatum species group (see notes for Diacamma magdalenae), the D. scalpratum group possesses a compressed petiole, but the striation of the head is longitudinal like in all species treated in the following. We place in this group three described species, D. scalpratum, Diacamma violaceum, and Diacamma longitudinale. The latter one is known from Vietnam and Laos (Emery 1889, Santschi 1920, 1924) and is readily distinguished by its longitudinal striation of the pronotum (compare also Diacamma palawanicum). Closest to the D. scalpratum group are two endemic species of Palawan (Philippines), D. palawanicum and Diacamma concentricum. They differ by several characters of the petiole.


Distribution based on Regional Taxon Lists

Oriental Region: Bangladesh, India (type locality), Myanmar, Pakistan.

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.


Different immature stages and adults of the wasp Schizaspidia diacammae (Chalcidoidea: Eucharitidae) were found inside several ant cocoons (Peeters et al., 2015). Wasp larvae were feeding on ant pupae, while other host cocoons yielded five wasp pupae as well as both male and female adults. Parasitized cocoons are cut in a distinct manner by the wasps when they exit, and this feature can be used to assess the prevalence of parasitism. Dissection of the ovaries of one recently emerged physogastric wasp female revealed thousands of eggs ready to be laid. Among 9 families of wasps parasitic on ants, only Eucharitidae (56 genera) specialize in attacking the immature stages of ants (see Eucharitid Wasps).

Association with Other Organisms

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This species is a host for the eucharitid wasp Schizaspidia diacammae (a parasite) (Universal Chalcidoidea Database) (primary host).

  • Schizaspidia diacammae eucharitid larva feeding on a Diacamma scalpratum pupa (Heraty et al. 2015, Fig. 11).



Images from AntWeb

Diacamma scalpratum casent0173640 head 1.jpgDiacamma scalpratum casent0173640 profile 1.jpgDiacamma scalpratum casent0173640 dorsal 1.jpgDiacamma scalpratum casent0173640 label 1.jpg
Worker. Specimen code casent0173640. Photographer April Nobile, uploaded by California Academy of Sciences. Owned by CAS, San Francisco, CA, USA.


Images from AntWeb

Diacamma scalpratum casent0173643 head 1.jpgDiacamma scalpratum casent0173643 head 2.jpgDiacamma scalpratum casent0173643 profile 1.jpgDiacamma scalpratum casent0173643 profile 2.jpgDiacamma scalpratum casent0173643 profile 3.jpgDiacamma scalpratum casent0173643 dorsal 1.jpgDiacamma scalpratum casent0173643 label 1.jpg
Male (alate). Specimen code casent0173643. Photographer April Nobile, uploaded by California Academy of Sciences. Owned by CAS, San Francisco, CA, USA.


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

  • scalpratum. Ponera scalprata Smith, F. 1858b: 84, pl. 6, figs. 21, 22 (w.) INDIA. Emery, 1889b: 496 (m.); Wheeler, G.C. & Wheeler, J. 1952c: 610 (l.). Combination in Diacamma: Mayr, 1862: 718. Senior synonym of compressum: Dalla Torre, 1893: 29; Emery, 1911d: 65.
  • compressum. Diacamma compressum Mayr, 1879: 660 (w.) INDIA. Junior synonym of scalpratum: Dalla Torre, 1893: 29.

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



Laciny et al. (2015) - Lectotype Diacamma compressum: TL 18.07; HW 2.82; HL 3.85; EL 0.76; SL 4.76; PH 2.48; PL 1.79; PW 1.28; SpD 0.50; SpL 0.45; WL 6.13; MTL 3.95. Indices: CI 73; SI 169; PI 72; SpDI 40; SpLI 36; EI 27. Paralectotype of D. compressum: TL 17.67; HW 2.74; HL 3.78; EL 0.77; SL 4.70; PH 2.48; PL 1.70; PW 1.29; SpD 0.51; SpL 0.45; WL 5.71; MTL 3.78. Indices: CI 72; SI 171; PI 68; SpDI 40; SpLI 35; EI 28. non-type (n = 6): TL 16.37–18.46; HW 2.64–2.84; HL 3.65–3.91; EL 0.76–0.82; SL 4.50–4.89; PH 2.32–2.51; PL 1.67–1.85; PW 1.11–1.35; SpD 0.42–0.60; SpL 0.47–0.59; WL 5.51–6.13; MTL 3.52–3.85. Indices: CI 72–76; SI 164–174; PI 69–77; SpDI 35–47; SpLI 36–51; EI 26–30.

Structures: Head elongated; sides long and parallel in front of eyes, moderately convex behind eyes. Eyes small, not protruding. Striation posterior of eyes divergent, meeting the narrow, medially slightly concave occipital margin; ridges matt, densely microreticulated, slightly narrower than interspaces. Occipital margin laterally slightly widened and terminating in very short, blunt projections. Clypeus finely, very densely punctured, except for anterior margin with larger and sparser puncturation; anteromedially with widely rounded apex. Mandible with obliterate fine striation, setae on masticatory margin very long. Mesosoma with coarse striation, especially on pronotum. Striae on pronotum transversely elliptical. Striation on mesosoma sides slightly oblique, upcurved on propodeum, reduced on mesopleura. Posterior face of propodeum separated from sides by strong carinae.

Petiole strongly compressed, with narrow dorsal crest posteriorly forked up to the closely spaced, long teeth; at sides the ridges as wide or slightly narrower than interspaces; subpetiolar process prominent, with strongly concave ventral outline, posterior corner longer than anterior one, anteriorly marginate. Gaster tergite 1 lacking striation, but with fine puncturation, shiny as the following tergites and sternites.

Pilosity: Standing setae on trunk short, those on head, pronotum, and abdominal apex slightly longer. Short appressed pilosity of trunk well developed, but on matt surfaces less obvious than on the shiny gaster where it is longer and velvety. Standing setae on scape very short, on legs short, slightly longer on flexor sides of femora.

Colour: Trunk black, without metallic shimmer. Clypeus and frontal lobes often reddish; subpetiolar process and broad stripes at posterior margins of gaster tergites and sternites pale reddish brown. Mandibles, femora and tibiae more or less extended red, other leg parts strongly infuscated. Colour of antennae variable.

Type Material

Laciny et al. (2015) - Mayr (1879) described D. compressum from two workers from “Sind in Ostindien im k. k. zoologischen Hofcabinete [old name for Naturhistorisches Museum Wien, Vienna] in Wien”; the type locality is attributed to Sindh in southern Pakistan. Both specimens are still in the collection of NHMW. One of them bears Mayr’s original identification labels whereas the second specimen bears a label “Collect. G. Mayr” and a label “scalpratum det. G. Mayr” which were both attached by the former curator, Anton Handlirsch. It is speculative why the specimens were differently labelled. Possibly the second specimen was kept by G. Mayr who changed the identification after Dall a Torre (1893) synonymized D. compressum with D. scalpratum in his catalogue.

  • Ponera scalprata: Holotype, worker, Sikkim, India, Hooker, The Natural History Museum.
  • Diacamma compressum: Lectotype (designated by Laciny, Pal & Zettel, 2015), India.

The following notes on F. Smith type specimens have been provided by Barry Bolton (details):

Ponera scalprata

Holotype worker in The Natural History Museum. Labelled “N. Ind. 54/16.” Acc. Reg.: “1854 no. 16. N. India (Sikkim, Him.) From Dr Hooker’s collection. Collected by Dr Hooker during his travels in n. India. A few of the insects were from Khasya Hills.”

A second scalprata specimen is in Oxford University Museum of Natural History, but here the usual data label is missing and has been replaced by a white card square with, “Phil. N. India.” The half-written then deleted Phil (= Philippines) raises the possibility that this specimen may not be from the original type-series.

Determination Clarifications

Laciny et al. (2015) - Records of D. scalpratum from Thailand (Antweb 2015: CASENT0173639, CASENT0173640; Peeters et al. 2015) refer to an undescribed species which will be a subject of further investigations.


References based on Global Ant Biodiversity Informatics

  • Collingwood C. A. 1962. Some ants (Hym. Formicidae) from north-east Asia. Entomologisk Tidskrift 83: 215-230.
  • Dad J. M., S. A. Akbar, H. Bharti, and A. A. Wachkoo. 2019. Community structure and ant species diversity across select sites ofWestern Ghats, India. Acta Ecologica Sinica 39: 219–228.
  • Emery C. 1889. Formiche di Birmania e del Tenasserim raccolte da Leonardo Fea (1885-87). Annali del Museo Civico di Storia Naturale 27: 485-520.
  • Emery C. 1911. Hymenoptera. Fam. Formicidae. Subfam. Ponerinae. Genera Insectorum 118: 1-125.
  • Forel A. 1900. Les Formicides de l'Empire des Indes et de Ceylan. Part VII. J. Bombay Nat. Hist. Soc. 13: 303-332.
  • Ghosh S. N., and S. Sheela. 2008. On a collection of Formicidae (Hymenoptera: Vespoidea) from Buxa Tiger Reserve, West Bengal, India, with new records of one rare genus and a rare species. Asian Myrmecology 2: 99-102.
  • IZIKO South Africa Museum Collection
  • Karmaly K. A.; S. Sumesh, T. P. Rabeesh, and L. Kishore. 2010. A checklist of ants of Thirunelli in Wayanad, Kerala. J. of the Bombay Natural History Society 107(1): 64-67.
  • Laciny A., A. Pal, and H. Zettel. 2015. Taxonomic notes on the ant genus Diacamma Mayr, 1862 (Hymenoptera: Formicidae), part 1. Zeitschrift der Arbeitsgemeinschaft Österreichischer Entomologen 67: 83-136.
  • Mathew R., and R. N. Tiwari. 2000. Insecta: Hymenoptera: Formicidae. Pp. 251-409 in: Director; Zoological Survey of India (ed.) 2000. Fauna of of Meghalaya. Part 7. [State Fauna Series 4.] Insecta 2000. Calcutta: Zoological Survey of India, 621 pp.
  • Musthak Ali T. M. 1991. Ant Fauna of Karnataka-1. Newsletter of IUSSI Indian Chapter 5(1-2): 1-8.
  • Rasheed M. T., I. Bodlah, A. G. Fareen, A. A. Wachkoo, X. Huang, and S. A. Akbar. 2019. A checklist of ants (Hymenoptera: Formicidae) in Pakistan. Sociobiology 66(3): 426-439.
  • Tiwari R.N., B.G. Kundu, S. Roychowdhury, S.N. Ghosh. 1999. Insecta: Hymenoptera: Formicidae. Pp. 211-294 in: Director; Zoological Survey of India (ed.) 1999. Fauna of West Bengal. Part 8. Insecta (Trichoptera, Thysanoptera, Neuroptera, Hymenoptera and Anoplura). Calcutta: Zoological Survey of India, iv + 442 pp.
  • Wheeler W. M. 1927. Burmese ants collected by Professor G. E. Gates. Psyche (Cambridge) 34: 42-46.