Monomorium tenebrosum Sparks

Sparks, Kathryn S., Andersen, Alan N. & Austin, Andrew D., 2014, Systematics of the Monomorium rothsteini Forel species complex (Hymenoptera: Formicidae), a problematic ant group in Australia, Zootaxa 3893 (4), pp. 489-529 : 524

Monomorium tenebrosum Sparks , NEW SPECIES

( Fig. 8 a–c, 11g)

Holotype worker. Western Australia, 10 km N Tom Price, -22.6019, 117.7457, 17 Oct 2009, K.S. Sparks, C. Petit, KSS177 (deposited in WAM).

Paratypes. Western Australia, 24 workers, same data as holotype (deposited in SAM, WAM).

Diagnosis. Large, glossy, dark brown species with a concave clypeal margin and a small median projection on the anteroventral clypeal margin. Propodeal longitudinal strigae present and appear to form a triangle with a carina that extends between dorsolateral angles.

Worker measurements (n=9). HW 0.98–1.03, HL 0.99–1.03, EL 0.2–0.21, PMH 0.35–0.37, PH 0.29–0.33, PNH 0.23, LHW 0.59–0.6, EW 0.12–0.14, PML 0.59–0.66, ML 0.99–1.09, PL 0.45–0.47, PNWdv 0.25–0.27.

Worker Description. Large species with a large, square head; posterior cephalic margin shallowly depressed medially. Anterodorsal margin of the clypeus concave with angulate frontolateral carinae extending beyond anteroventral clypeal margin forming obtuse angles, carinae with a wavy margin; anteroventral margin with a small median projection. Frons strigate, restricted to antennal lobes and area in between or limited to a few strigae only present on antennal lobes; coarse lateral cephalic strigae reach anterior eye margin. Eyes medium, EW 0.20–0.23 x LHW, 13 ommatidia in longest vertical axis, 11 in longest horizontal axis.

Mesonotum rugulose-strigulate on lateral curvature only, remainder smooth and shining, rarely with strigulae on posterior region; metapleural groove shallow. Mesopleuron alveolate with a few irregular strigulae extending anteriorly from metanotal groove. Propodeum in lateral view with dorsolateral angles clearly forming an obtuse angle, sculpture alveolate, with strigae extending over metapleural gland bulla but not reaching metanotal groove, a few strigulae on lateral face of posterodorsal corners; dorsal surface with anterolateral transverse carina weekly present, transverse strigae indistinct, longitudinal strigae present and forming a triangle with a carina that extends between posterodorsal corners. Petiole node narrow, less than 2 x eye width when viewed from above shape in posterior view tapering from widest point to narrowly rounded apex, in lateral view with anterior and posterior faces converging, apex narrow and rounded; posterior surface finely reticulate, restricted to lateral surface and basal margin, postpetiole finely reticulate, smooth dorsally. T1 completely smooth and without sculpture.

Head, mesosoma and legs dark chestnut brown except trochanters light brown and mandibles orange brown, metasomal tergites dark brown, almost black, cuticle with a high gloss.

Distribution. This species is know from a single locality in the Pilbara region of Western Australia. Its range overlaps with M. pilbara sp. nov. and M. subapterum .

Etymology. The specific name is taken from the Latin word for “dark” and refers to the dark brown colour of this species.

Remarks. Although this species is described from a single collection from one locality in the Pilbara region in Western Australia, it is both morphologically and genetically distinct ( Sparks et al. 2014) from any other species in the complex.

COI sequences. Genbank accession number for this species is: KC57280.

Figures

FIGURE 8. Workers of the M. rothsteini (Forel) species complex in lateral, head and dorsal view of the mesosoma. Fig. 8 a – c: M. tenebrosum, holotype (10 km N Tom Price, WA, KSS 177), d – f: M. topend, holotype (Darwin, NT, TERC 75), g – i: M. torrens, paratype (Flinders Rangers, SA, KSS 4). Scale bars are 0.5 mm for all views.