Key to Australian Colobostruma Species

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The following key to Australian Colobostruma is based on Shattuck (2000).[1].

1

  • Lateral postpetiole with sides approximately vertical, not expanded outwards; antennae 4 segmented => Colobostruma cerornata
  • Lateral postpetiole drawn outwards into thin flange-like wings; antennae with 4 or more segments => 2

2

  • In side view the dorsum of the mesosma broadly arched, the propodeum low, its posterior face greatly reduced, approximately the same height as the petiolar peduncle and with very narrow, thickened lamellae => Colobostruma nancyae
  • In side view the dorsum of the mesosoma at most weakly convex, the propodeum high, its posterior face at most only slightly less in height than the petiolar node and with broad, thin lamellae => 3

3

  • Wing of postpetiole with a single translucent window along its posterior margin, its anterior margin formed by a band of thickened integument => 4
  • Wing of postpetiole with translucent windows along both its anterior and posterior margins, the windows separated by a narrow band of thickened integument (the anterior window always smaller than the posterior window and sometimes reduced to a narrow band along the anterior edge) => 5

4

  • Antennae with 4 (or rarely 5) segments (if 5 segmented the second segment from the tip much shorter than the other segments) => Colobostruma elliotti
  • Antennae with 6 (or rarely more) segments => 6

5

  • Frontal lobes immediately above the antennal insertions and the lateral margins of the clypeus raised above the surrounding surface of the head => 7
  • Frontal lobes and lateral margins of the clypeus smooth relative to the surrounding surface of the head => 8

6

  • Antennae (scape) gently elbowed, lacking a ventral lobe, its diameter changing gradually along its length => Colobostruma australis
  • Antennae (scape) strongly elbowed, with a ventral lobe, its widest point across the lobe => 9

7

8

  • Antennae with 4 segments, or if with 5, the second segment from the tip is much shorter than the third segment from the tip => 10
  • Antennae with 5 or more segments, when 5 segmented the second and third segments from the tip are approximately the same length => 11

9

  • In full face view the ridges immediately in front of the eyes nearly parallel or diverging anteriorly => Colobostruma papulata
  • In full face view the ridges immediately in front of eyes converging anteriorly => Colobostruma froggatti

10

  • Second segment of the funiculus from the scape long, more than twice the length of the first segment => Colobostruma alinodis
  • Second segment of the funiculus from the scape short, at most only slightly longer than the first segment => 12

11

  • Front of the head extremely flattened and disk-like (phragmotic), the clypeus and frontal lobes expanded laterally into a thin, sharply-edged flange, the anterior sections of the head separated from the posterior sections by an angle at about the level of the eyes => Colobostruma leae
  • Front of the head not unusually flattened (not phragmotic), the clypeus and frontal lobes separated from the lateral surfaces of the head by an angle, the entire head in approximately the same plane => 13

12

  • Posterior faces of petiole and postpetiole convex; known from Queensland and northern New South Wales => Colobostruma biconvexa
  • Posterior faces of petiole and postpetiole concave; known from the ACT and South Australia => Colobostruma biconcava

13

  • Occurring in South Australia or Western Australia => Colobostruma mellea
  • Occurring in Queensland or New South Wales => 14

14

  • Posterior margin of the head forming a shallow "V", with relatively flat sides which meet medially in an angle; in dorsal view, the tips of the pronotal angles (immediately behind head) forming the widest point of the pronotum => Colobostruma lacuna
  • Posterior margin of the head a gentle, uniform convexity; in dorsal view the anterior one-third of the pronotum approximately parallel, the tips of the angles at most only slightly wider than the medial region of the pronotum => Colobostruma sisypha

References

  1. Shattuck, S.O. (2000) The epopostrumiform genus group. pp. 30–67 in Bolton, B. The ant tribe Dacetini. Memoirs of the American Entomological Institute, 65, 1–1028