The teeth of the mandibles (see identification section), together with the stoutly produced clypeal denticles, suggests that the ant may be a graminivore, but little is known of its biology. A label with the Jabiru specimens states that they were found foraging on the ground in Eucalyptus forest. (Heterick 2001)
Heterick (2001) - A member of the longinode group. Monomorium bifidum is the only known Monomorium with two mandibular teeth. The bottom tooth is larger than the top tooth, and both are broad and flattened with a scissor-like edge.
This species varies little across its range, but the Dimbulah specimens have reddish gasters, while workers from Western Australia and most of those from the Northern Territory have black gasters. The Jabiru specimens, however, fall between these two extremes. (Similar variation in the colour of the worker gaster has already been described for Monomorium bicorne.)
Keys including this Species
Distribution based on Regional Taxon Lists
Distribution based on AntMaps
Distribution based on AntWeb specimens
Check data from AntWeb
The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.
- bifidum. Monomorium bifidum Heterick, 2001: 390, figs. 30, 63, 70 (w.) AUSTRALIA.
Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.
Holotype. HML 3.43; HL 1.40; HW 1.31; Cel 93; SL 0.83; SI 63; PW 0.68. Others. HML 3.39-3.85; HL 1.38-1.57; HW 1.35-1.48; Cel 90-96; SL 0.75-0.90; SI 60-63; PW 0.61--0.69 (7 measured).
As for the worker of Monomorium longinode, but with the following apomorphies.
Head. Frons of head capsule longitudinally striate with combination of appressed setulae and erect and suberect setae. (Viewed from front) compound eyes set in anterior half of head capsule. Antennal club gradually tapering and barely discernible. Anteromedial clypeal margin emarginate, median clypeal carinae produced apically as pair of pronounced teeth. Posteromedial clypeal margin situated between anterior and posterior surfaces of antennal fossae. Frontal lobes parallel straight. Maximum number of mandibular teeth and denticles: two.
Alitrunk. Dorsal promesonotal face evenly convex; erect and suberect promesonotal setae 5-l0. Mesonotal suture visible externally as faint ridge. Dorsal propodeal face gently convex; processes present on posterior propodeal angles in form of minute lamellae. Erect and suberect propodeal setae absent or very sparse; propodeal setulae appressed.
Petiole and postpetiole. Petiolar node cuboidal; sculpture present in form of microreticulation. Ratio of greatest node breadth (viewed from front) to greatest node width (viewed in profile) near 1 : 1. Height ratio of petiole to postpetiole near 3:4 to near 1: 1; height-length ratio of postpetiole near 4:3 to near l: l. Sculpture present in form of microreticulation.
General characters. Colour a uniform russet, or reddish with a black gaster. Worker caste monomorphic.
- Holotype, worker, 30km SW Katherine, Northern Territory, Australia, Greenslade,P.J.M., ANIC32-015716, Australian National Insect Collection.
- Paratype, 7 workers, 22km SE Katherine, Northern Territory, Australia, Australian National Insect Collection.
- Paratype, 1 worker, 27km SE Katherine, Northern Territory, Australia, Australian National Insect Collection.
- Paratype, 2 workers, Manbulloo, SW Katherine, Northern Territory, Australia, The Natural History Museum.
- Paratype, 1 worker, 24km SE Katherine, Northern Territory, Australia, Museum of Comparative Zoology.
Latin: “cleft”, with reference to the mandibles.
- Heterick, B. E. 2001. Revision of the Australian ants of the genus Monomorium (Hymenoptera: Formicidae). Invertebrate Taxonomy. 15:353-459. PDF (page 390, figs. 30, 63, 70 worker described)