Mesostruma browni

Identification
Mesostruma browni is similar to Mesostruma bella and is broadly sympatric with it. It differences as follows.
 * The posterior margin of the head is shallowly concave and the lateral corners are broadly rounded while in M. bella this region is more deeply concave and its lateral corners are more sharply angular.
 * The sculpturing on the metapleural gland bulb consists of large fovae and irregular rugae while in M. browni the sculpturing on the bulb consists of small, closely spaced punctures, sometimes with up to several weak rugae.
 * The upper margins of the propodeal lamellae, in lateral view, are sinuate (convex basally, concave near the angle) and the posterior margin have a distinct concavity just below the dorsal angles. In M. bella they are convex and the posterior margins have a very weak concavity just below the dorsal angles.
 * Mesostruma browni averages smaller (HW 0.62 mm to 0.75 mm) than M. browni (HW 0.72 mm to 0.84 mm).

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  browni. Mesostruma browni Taylor, 1962: 1, figs. 1-5 (w.q.m.) AUSTRALIA. Wheeler, G.C. & Wheeler, J. 1973c: 212 (l.). See also: Shattuck, in Bolton, 2000: 49.

Holotype worker, paratype workers and male, AUSTRALIA: New South Wales, 2 mi E of Berry, 28.xii.1959 (B. B. Lowery) ( (3W)); paratype workers and queens, New South Wales, Sydney, Burns Bay, Riverview College, 19.iv.1959 (B. B. Lowery) ( (3W)); Burns Bay, 2.ii.1959 (B. B. Lowery) ( (1Q DATE AS 20 Feb 1959); Barrington Tops (T. E. Woodward); Pymble, 18.iii.1956 (C. Mercovich) [examined by Shattuck, 2000].

Description
WORKER. TL 3.1 - 3.9, HL 0.69 - 0.83, HW 0.62 - 0.74, CI 89 - 91, ML 0.32 - 0.38, MI 42 - 49, SL 0.42 - 0.45, SI 61 - 66, PW 0.45 - 0.50, AL 0.74 - 0.92. Head relatively broad (CI > 88), its posterior margin relatively shallowly concave; eyes relatively small (maximum eye diameter/head length <= 0.20). Pronotum relatively wide (about 0.66-0.69 times mesosomal length), in dorsal view its anterolateral corners rounded. 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. Propodeal lamellae with the dorsal margins sinuate (convex basally, concave near angle), the posterior margins weakly concave, the angles between these margins acute, less than 90 degrees. Sculpturing on the metaplerual gland bulb consisting of large fovae and irregular rugae. Postpetiole expanded laterally and wing-like. First gastral segment immediately posterior of the postpetiole essentially smooth, sometimes with very slight irregularities. Body relatively small (maximum head width < 0.73mm), colour dark honey yellow.