This appealing little ant is inconspicuous, and probably more abundant than the distribution records suggest. (Heterick 2001)
Heterick (2001) - A member of the falcatum group. This is the only Australian Monomorium with 10-segmented antennae. Nonetheless, the form of the propodeum and of the body sculpture clearly places Monomorium decuria in the same species-group as Monomorium elegantulum, Monomorium falcatum and Monomorium lacunosum.
Heterick (2009) - Aside from members of some populations of putative Monomorium sydneyense, this is the only Australian Monomorium with a 10-segmented antenna.
Keys including this Species
- Key to Australian Monomorium Species
- Key to Monomorium of the southwestern Australian Botanical Province
Heterick (2009) - Confined to the south-west corner of WA, this species has a more localized distribution than most of the other members of its species group. However, it is easily the most common.
Distribution based on Regional Taxon Lists
Distribution based on AntMaps
Distribution based on AntWeb specimens
Check data from AntWeb
Heterick (2001) - In southwestern Australia, the species occupies habitats ranging from wet sclerophyll forest to coastal Banksia and Dryandra scrubland.
I observed activity at a nest in semi-rural bush and parkland in Kwinana, Western Australia, where the ants were foraging nocturnally on sand with sparse ground cover. The workers moved very slowly across the ground surface. The entrance to the nest was a minute hole, barely larger than an individual worker. No excavated soil or other material could be seen around the nest.
Heterick 2009 - Occurs in woodlands, up to the outskirts of towns and cities, including the Perth metropolitan area.
The following information is derived from Barry Bolton's New General Catalogue, a catalogue of the world's ants.
- decuria. Monomorium decuria Heterick, 2001: 379, figs. 24, 69 (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 1.70; HL 0.69; HW 0.63: Cel 92; SL 0.43; SI 67; PW 0.39. Other. HML 1.41-1.83; HL 0.56-0.74; HW 0.52-0.72; Cel 92-97; SL 0.36-0.46; SI 65- 74; PW 0.28-0.41 (9 measured).
As for the worker of Monomorium falcatum, but with the following apomorphies.
Head. Frons of head capsule microreticulate and striolate with combination of appressed setulae and erect and suberect setae. (Viewed from front) compound eyes set at midpoint of each side of head capsule; (viewed laterally) compound eyes set posterior of midline ofhead capsule; eye moderate, eye width 0.5-1.5x greatest width of antennal scape. Antennal segments 10. Longest lateral anterior clypeal setae long, extending beyond dorsal margin of closed mandibles. Maximum number of mandibular teeth and denticles: five; mandibles (viewed from front) triangular and striate, with piliferous punctures; apical and basal mandibular margins meeting in tooth or denticle.
Alitrunk. Promesonotum with uniform microreticulation and dorsal foveae; evenly convex dorsally; erect and suberect promesonotal setae absent to >5; setulae appressed. Mesonotal suture absent. Metanotal groove absent. Propodeal processes present on posterior propodeal angles as small denticles or sharp flanges. Propodeal angle absent; propodeal setulae appressed.
Petiole and postpetiole. Ratio of greatest node breadth (viewed from front) to greatest node width (viewed in profile) near 4:3. Anteroventral process always present as pronounced spur. Ventral lobe present in some individuals. Height-length ratio of postpetiole near 2:1 to near 4:3. Ventral process absent or vestigial.
General characters. Colour light brown, head and gaster darker, appendages tawny yellow. Worker caste monomorphic.
Holotype. Worker, Western Australia, Kwinana, 31.i.l987, B. E. Heterick, soil, mixed native/ exotic veg., semi rural environment, 125/6MonBH49 (Australian National Insect Collection). Paratypes. Western Australia: 2x4 workers, Geraldton, 300 miles N of Perth, 22.v.l963, C. Mercovich, 300 ft., ca 15 miles inland, savannah woodland, 10 seg. antennae, Chelaner (The Natural History Museum and Museum of Comparative Zoology).
- Holotype, worker, Kwinana, Western Australia, Australia, Heterick,B.E., ANIC32-015726, Australian National Insect Collection.
- Paratype, 4 workers, Geraldton, Western Australia, Australia, The Natural History Museum.
- Paratype, 4 workers, Geraldton, Western Australia, Australia, Museum of Comparative Zoology.
Latin: “division of ten”.
- Heterick, B. E. 2001. Revision of the Australian ants of the genus Monomorium (Hymenoptera: Formicidae). Invertebrate Taxonomy. 15:353-459. PDF (page 379, figs. 24, 69 worker described)
- Heterick, B. E. 2009. A guide to the ants of South-western Australia. Records of the Western Australian Museum, Supplement 76:1-206. PDF