Key to Australian Mesostruma Species

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

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