Proceratium williamsi

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Proceratium williamsi
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Hymenoptera
Family: Formicidae
Subfamily: Proceratiinae
Tribe: Proceratiini
Genus: Proceratium
Species: P. williamsi
Binomial name
Proceratium williamsi
Tiwari, 2000

Proceratium-williamsi hal.jpg

Proceratium-williamsi had.jpg


This species was found mainly in leaf litter of primary, subtropical forests of Himalaya and occasionally in soil samples of secondary forests collected in cool shady places. Although infrequent in collections, this species seems to be widely distributed throughout the Himalayan ranges (Bharti & Wachkoo, 2014).


A member of the itoi clade. Differing from its sister species, Proceratium malesianum, by the absence of erect hairs in the worker. (Baroni Urbani and de Andrade 2003)

Key to Indomalayan Proceratium Species

Keys including this Species


Latitudinal Distribution Pattern

Latitudinal Range: 30.4966° to 29.35000038°.

Tropical South

Distribution based on Regional Taxon Lists

Oriental Region: Bhutan, India (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.



Explore-icon.png Explore Overview of Proceratium biology 
Very little is known about the biology of Proceratium ants. They nest in soil, rotten wood, under deep-set stones and, in a few cases, tree branches. For many species the nest consists of small rounded chambers hollowed out of soft rotten wood or in the soil. Toward the cooler limits of the range, particularly in North America, nests and foraging workers are found under deep set rocks instead of in rotten wood. The nest site is usually in forest shade, in old moist gardens, or similar habitats that are constantly moist. Some species of known to be egg predators of arthropods, especially of spiders.

Most Proceratium are relatively rare but this is not the full explanation for why they are not commonly collected. Colonies of most species are small. Based on anectdotal natural history information from a few species, it was once thought that most Proceratium would likely be found to have mature colonies that contain somewhere between 10 - 50 workers. Yet nests with more than 50, and in some cases up to 200, workers have been been reported. Besides small colonies, these ants also do not appear to forage in places where they are readily encountered.

Males and females are though to be produced in small numbers but we generally do not have enough data for colonies of any species to know what might be typical. Reproductive flights have been observered toward the end of the summer in some northern temperate areas. In these regions the nuptial flight occurs during the last half of August. Both sexes climb some distance from the nest entrance before taking flight. Workers too issue from the nest during the nuptial flight, as is often the case with otherwise cryptobiotic ants. ‎



Images from AntWeb

Proceratium bhutanense H casent0281860.jpgProceratium bhutanense P casent0281860.jpgProceratium bhutanense D casent0281860.jpgProceratium bhutanense L casent0281860.jpg
Specimen code casent0281860.jpg. .


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

  • williamsi. Proceratium williamsi Mathew & Tiwari, 2000: 273, figs. 14-15 (w.q.) INDIA (Meghalaya).
    • Type-material: holotype worker, 2 paratype workers, 3 paratype queens.
    • Type-locality: holotype India: Meghalaya, East Khasi Hills, Shillong, Risa Colony,14.v.1976 (R. Mathew); paratypes with same data.
    • Type-depositories: NZSI (holotype); NZSI, NZSS (paratypes).
    • Status as species: Bharti & Wachkoo, 2014b: 70; Bharti, Guénard, et al. 2016: 54.
    • Senior synonym of bhutanense: Bharti & Wachkoo, 2014b: 70.
    • Distribution: Bhutan, India.
  • bhutanense. Proceratium bhutanense De Andrade, in Baroni Urbani & De Andrade, 2003b: 278, figs. 116-117 (w.) BHUTAN, INDIA (West Bengal, Uttar Pradesh, Meghalaya).
    • Type-material: holotype worker, 2 paratype workers.
    • Type-locality: holotype Bhutan: Phuntsholing, 2/400 m., 15.4, Nat.-Hist. Museum Basel- Bhutan Expd. 1972 (no collector’s name, probably C. Baroni Urbani); paratypes with same data.
    • Type-depositories: NHMB (holotype); MRSN, NHMB (paratypes).
    • Junior synonym of williamsi: Bharti & Wachkoo, 2014b: 70.

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



Holotype. TL 2.92; HL 0.68; HW 0.68; CI 100; SL 0.42; SI 62; PW 0.47; ThL 0.79.

Paratypes: TL 2.87-2.89; HL 0.63-0.71; HW 0.68; CI 96- 108; SL 0.45; SI 66; PW 0.45-0.47; ThL 0.82. Similar to holotype.

Head as long as broad, occipital margin round; the median cIypeal margin produced in the middle, mandibles tridentate; eyes very minute, placed about the middle of the head laterally; antennae stout; thorax round, thoracic sutures not distinct; apical portion of metanotum concave, bordered on either side by a carina; node of pedicel broad, broader than long, briefly petiolate in front, with a short appendix beneath; abdomen stout, convex; legs moderate; the whole insect densely punctate and with a silky gloss; hairs on body sparse, few on the mandibles at the base of the masticatory region; pubescence dense, golden yellow, almost covering the sculpture.

Colour: Reddish brown.

De Andrade (2003) - P. bhutanense: Head slightly longer than broad, its sides subparallel anteriorly and gently converging posteriorly. Vertex in full face view straight. Clypeus medially reduced, triangular or subround, between and slightly longer than the antennal sockets. Clypeal dorsum with longitudinal carina. Antenna1 socket with broad torulus. Frontal carinae separate from each other, partially covering the antennal insertions. Frontal area behind the frontal carinae convex. Lateral expansions of the frontal carinae relatively narrow, raised, diverging. Genal carinae marked. Eyes small, appearing as a dark dot below the integument and placed on the midline of the head. First funicular joint subequal in length and width. Funicular joints 2-10 much broader than long. Last funicular joint about as long as the sum of joints 6-10. Scapes much short of the vertexal margin and gently thickening apically. Masticatory margin of the mandibles with 2-3 denticles before the pointed apical tooth. Palp formula 3,2.

Mesosoma slightly longer than the maximum head length (mandibles included). Promesopleural and meso-metapleural sutures impressed ventrally only. Basal face of the propodeum weakly declivous. Declivous face of the propodeum gently concave anteriorly. Basal and declivous faces of the propodeum laterally separate by a carinate denticle or tooth. Sides of the declivous face of the propodeum with a lamella broader posteriorly. Propodeal spiracle round and above the mid height in lateral view.

Petiole convex in profile, with the sides diverging and convex posteriorly in dorsal view; petiolar node relatively flat. Anterior border of the petiole deeply concave and carinate, the carina strongly denticulate on each side.

Ventral process of the petiole triangular or spiniform. Postpetiole broader than the petiole anteriorly; its sides diverging and gently convex posteriorly. Postpetiolar sternite anteromedially with a superficially marked subtriangular projection and straight in side view. Constriction between postpetiole and first gastral segment impressed. Gastral tergite I strongly convex on the curvature. Remaining gastral tergites and sternites curved ventrally.

Legs slender but not very elongate. All tibiae with a pectinate spur. Spurs of fore legs without basal spine. Fore basitarsi longer than the mid ones. Hind basitarsi about 1/3 shorter than hind tibiae. Second tarsomere of hind legs slightly shorter than the fourth. Pretarsal claws simple. Arolia present.

Sculpture. Head, mesosoma, petiole and postpetiole granulate. First gastral tergite smooth and covered by sparse piligerous punctures; the punctures denser and more marlced on the posterior border and on the sides. Legs granulate, the granulation less marked than on the other body parts.

Body covered by hairs of two main types: (1) short, dense, subdecumbent on the whole body; (2) shorter than hair type (I), dense and subdecumbent on the funicular joints. In addition the funicular joints bear whitish, thick, appressed, sparse hairs.

Colour. Brown or dark brown.

Measurements in mm and Indices: TL 2.92-3.39; HL 0.65-0.76; HW 0.60-0.68; EL 0.03-0.04; SL 0.41-0.48; WL 0.80-0.92; PeL 0.25-0.30; Pew 0.25-0.32; HFeL 0.52-0.56; WTiL 0.43-0.47; HBaL 0.28-0.32; LS4 0.21-0.26; LT4 0.63-0.83; CI 89.3-93.0; ,5161.1-63.1 ; IGR 0.3 1-0.34.


TL 4.13-4.34; HL 0.92; HW 0.76; CI 83; SL 0.74; SI 97; PW 0.68; ThL 1.32; DE 0.16.

Head longer than broad; eyes prominent, placed about the middle of the head laterally; ocelli prominent; cIypeal margin anteriorly not produced in the middle; mandibles with few longitudinal striae; masticatory margin broad, armed with ten to eleven small teeth, apical two prominent; sides of head straight, posterior margin round, frontal carinae raised, spatulate; clypeal region concave; clypeal concavity on either side with transverse striae, striae bent towards the mandibular base; erect to suberect hairs on body numerous; densely pubescent; the whole insect densely punctured.

Type Material

Holotype worker: India: Meghalaya; East Khasi hills, Shillong, Risa Colony, 14.v.76, CoIl. R. Mathew. Paratypes : 2 workers and 3 females with the same collection data as that of the holotype.

Baroni Urbani and De Andrade (2003) - P. bhutanense Holotype worker from Phuntsholing, Bhutan labelled "Phuntsholing, 2/400 m, 15 4, Nat. - Hist. Museum Basel - Bhutan Expedltlon 1972" in Naturhistorisches Museum, Basel, 1 paratype worker same data and collection as the holotype, 1 paratype worker In MRSN.


References based on Global Ant Biodiversity Informatics

  • Baroni Urbani C., and M.L de Andrade. 2003. The ant genus Proceratium in the extant and fossil record (Hymenoptera: Formicidae). Museo Regionale di Scienze Naturali, Monografie 36: 1-480.
  • Bharti H., and A. A. Wachkoo. 2014. New synonymy of Proceratium williamsi Tiwari (Hymenoptera, Formicidae). ZooKeys 388: 69–72. doi: 10.3897/zookeys.388.6972
  • CSIRO Collection