Mesostruma spinosa, Shattuck, Steven O., 2007

Shattuck, Steven O., 2007, New species of Myrmicine ants from Western Australia (Hymenoptera: Formicidae), Zootaxa 1661, pp. 47-53 : 51-52

Mesostruma spinosa new species

( Figs 9–12 )

Description: Holotype worker. TL 2.9, HL 0.69, HW 0.56, CI 81, MandL 0.21, MandI 30, SL 0.41, SI 73, PW 0.40, ML 0.77. In dorsal view the anterolateral corners of pronotum rounded. Dorsum of mesosoma with scattered, shallow foveolate punctures spaced more than their width apart, the area between punctures smooth and lacking sculpturing. Propodeum armed with elongate spines, propodeal lamellae reduced to thin bands and essentially absent. Sculpturing on metapleural gland bulb consisting of indistinct rugae and punctures. Lateral surfaces of postpetiole rounded. First gastral segment immediately posterior of postpetiole smooth. Body colour yellow-red with light infuscation on dorsum of head above eyes, clypeus and first gastral tergite.

Material examined: Holotype worker from Western Australia, Manjimup (34°15'S 116°09'E), July, 1977 (J. D. Majer) ( ANIC, No. 32-007281 ).

Comments: Mesostruma spinosa can be separated from all other known species in this genus by the presence of distinct, elongate propodeal spines, the lack of broad propodeal lamellae and the narrower head (CI = 81, CI is greater than 88 in the other known species). There is little chance it will be confused with any other species. This species, together with M. inornata and M. loweryi , have only been collected once. Only one species, M. eccentrica , is at all common in Western Australia, having been collected over 10 times. It is likely that additional species remain to be discovered in this part of Australia. The single known specimen of M. spinosa was collected from a pitfall trap.

The following modifications to the key provided by Shattuck (2000) will allow the identification of this species.

3. Dorsum of alitrunk 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 alitrunk with scattered, shallow foveolate punctures which are spaced more than their width apart, the area between the punctures smooth and lacking sculpturing ................................................ 4A

4A. Propodeum armed with elongate spines, the lamellae reduced to thin bands which are only slightly raised above the underlying propodeal surface ............................................................................. spinosa Propodeum lacking spines and with thick lamellae ................................................................................ 5

Figures

FIGURES 9 – 12. Mesostruma spinosa Shattuck (holotype). 9, front of head; 10, lateral body; 11, dorsal body; 12, specimen labels.