Key to Australian Proceratium Species

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The following worker key to Australian Proceratium is based on Baroni Urbani & de Andrade (2003)[1].


  • Petiolar node low and rounded; leading edge of clypeus projecting forward and the insertions of the antennae well back from the edge => 2
  • Petiolar node high and box-like; leading edge of clypeus straight and the insertions of the antennae very close to the edge => 3


  • Postpetiole concave medially and gently lobate laterally; erect hairs on sides of head sparse and short (length less than the maximum width of the scape) => Proceratium cavinodus
Head of Proceratium cavinodus worker
Profile of Proceratium cavinodus worker

  • Postpetiole flat medially and convex laterally; standing hairs on the sides of head abundant and long (length greater than the maximum width of the scape) => Proceratium stictum
Head of Proceratium stictum worker
Profile of Proceratium stictum worker


  • When viewed from above, petiole more than 1.5 times wider than long; smaller, total length less than 2.63mm => Proceratium pumilio
Head of Proceratium pumilio worker
Profile of Proceratium pumilio worker
  • When viewed from above, petiole at most 1.5 times wider than long; almost always larger (total length greater than 2.64mm, if smaller then PeW less than 0.27mm) => 4


Head of Proceratium hirsutum worker
Profile of Proceratium hirsutum worker
  • Erect hairs on body short; scapes relatively short (SI less than 0.70) => 5


  • Postpetiole smooth or at most with very weak sculpturing => 6
  • Postpetiole with strong and dense sculpturing => 7


  • Central region of leading edge of clypeus projecting forward of the lateral regions; long hairs on gaster sparse and suberect; head relatively long and narrow (cephalic index less than 0.93), the scape relatively long (scape index greater than 0.68) => Proceratium gracile
Head of Proceratium gracile worker
Profile of Proceratium gracile worker
  • Leading edge of clypeus essentially flat across its entire width; long hairs on gaster denser, subdecumbent and decumbent; head broader and nearly square (cephalic index more than 0.94), the scape relatively short (scape index less than 0.65) => Proceratium robustum
Head of Proceratium robustum worker
Profile of Proceratium robustum worker


  • Mesosoma strongly convex in profile, the propodeum lower than the mesonotum and rounded; propodeal sides with a tooth; head relatively narrow (cephalic index less than 0.85), the sides more or less parallel; body larger (total length about 3.72mm) => Proceratium gigas
  • Mesosoma more elongate, the propodeum only slightly lower than the mesonotum and its dorsal face flatter; propodeal sides at most denticulate; head relatively wide (cephalic index greater than 0.89), the sides tapering inwards towards the mandibles; body smaller (total length less than 3.5mm) => Proceratium australe
Head of Proceratium australe worker
Profile of Proceratium australe worker


  1. Baroni Urbani, C., de Andrade, M.L. (2003) The ant genus Proceratium in the extant and fossil record (Hymenoptera: Formicidae). Museo Regionale di Scienze Naturali, Monografie, 36, 1–492.