Key to Australian Mesostruma Species

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

1

  • In dorsal view anterolateral pronotum armed with distinct angles or short spines => 2
  • In dorsal view anterolateral pronotum rounded => 3

2

  • Propodeal lamellae well developed; lateral surfaces of postpetiole with well developed wings => Mesostruma laevigata
  • Propodeal lamellae reduced to thin carinae; lateral surfaces of postpetiole rounded, lacking wings => Mesostruma eccentrica

3

  • Dorsum of mesosoma with dense, shallow foveolate punctures which are generally spaced less than their width apart, and with the area between the punctures with weak but distinct sculpturing => 4
  • Dorsum of mesosoma with scattered, shallow foveolate punctures which are spaced more than their width apart, the area between the punctures smooth and lacking sculpturing => 5

4

  • Sculpturing on base of first gastral segment (immediately posterior of the postpetiole) consisting of evenly spaced, elongate rugae and fine microreticulations; head essentially square (CI 0.96 - 1.03) => Mesostruma turneri
  • Sculpturing on base of first gastral segment (immediately posterior of the postpetiole) consisting of irregular, very short rugae, the underlying integument smooth; head longer than broad (CI less than 0.95) => Mesostruma inornata

5

  • Propodeum armed with elongate spines, the lamellae reduced to thin bands which are only slightly raised above the underlying propodeal surface => Mesostruma spinosa
  • Propodeum lacking spines and with thick lamellae => 6

6

  • Head relatively narrow (CI less than 0.88); propodeal lamellae with posterior margins flat, the dorsal angles 90 degrees or greater => Mesostruma loweryi
  • Head relatively broad (CI greater than 0.88); propodeal lamellae with posterior margins concave, the dorsal angles acute, less than 90 degrees => 7

7

  • Pronotum relatively narrow (about 0.58-0.62 times mesosomal length); in side view, anterior and dorsal faces of petiole separated by a sharp convexity, often with weak denticles at the angle; in side view, upper margins of propodeal lamellae flat to weakly concave and the posterior margins relatively strongly concave => Mesostruma exolympica
  • Pronotum relatively wide (about 0.66-0.69 times mesosomal length); in side view, anterior and posterior faces of petiole rounding gradually into each other and never with denticles; in side view, upper margins of propodeal lamellae convex or sinuate and the posterior margins relatively weakly concave => 8

8

  • Posterior margin of head relatively deeply concave, the lateral corners sharply angular; sculpturing on metapleural gland bulb small, closely spaced punctures occasionally with up to several weak rugae; in side view, upper margin of propodeal lamellae convex and the posterior margins with a very weak concavity just below the dorsal angles; body larger, head width > 0.72 mm => Mesostruma bella
  • Posterior margin of head relatively shallowly concave, the lateral corners rounded; sculpturing on metaplerual gland bulb large fovae and irregular rugae; in side view, upper margins of propodeal lamellae sinuate (convex basally, concave near angle) and the posterior margins with a distinct concavity just below dorsal angles; body smaller, head width < 0.75 mm => Mesostruma browni

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.