Monomorium silaceum

Monomorium silaceum
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Formicidae
Subfamily:	Myrmicinae
Tribe:	Solenopsidini
Genus:	Monomorium
Species:	M. silaceum
Binomial name
	Monomorium silaceum; Heterick, 2001 Specimen Labels

Monomorium silaceum does not appear to be as common as some of the other small, yellow Monomorium, and populations are mainly concentrated in the northern half of the Australian mainland. The species is known only from workers.

Identification

Heterick (2001) - A member of the monomorium group. The broad head capsule and very large eyes identify M. silaceum. Fresh worker specimens have a head capsule that is darker in full-face view than the promesonotum, but this feature seems to fade in older material.

Normally, the propodeum of M. silaceum is rather cuboidal and sculptured, with a large propodeal spiracle. In the case of a series of three paratype workers from Mt Whaleback, however, the general appearance of the propodeum is smoother and more gracile, resembling that of Monomorium laeve.

Heterick (2009) - One of a trio (also Monomorium disetigerum, Monomorium micula) of small, yellow species from drier regions that can often be hard to distinguish from pale Monomorium sydneyense. WA Monomorium silaceum populations in some areas of the north and north-east of the SWBP and the Pilbara departs from the typical broad-headed, punctate yellow form. These variants have a brown head capsule, are smoother and less sculptured, and are more gracile.

Keys including this Species

Distribution

Latitudinal Distribution Pattern

Latitudinal Range: 22.5045° to -26.13332939°.


North Temperate	North Subtropical	Tropical	South Subtropical	South Temperate

Source: AntMaps

Distribution based on Regional Taxon Lists

Australasian Region: Australia (type locality).

Distribution based on AntMaps

Distribution based on AntWeb specimens

Check data from AntWeb

Countries Occupied

Number of countries occupied by this species based on AntWiki Regional Taxon Lists. In general, fewer countries occupied indicates a narrower range, while more countries indicates a more widespread species.

Estimated Abundance

Relative abundance based on number of AntMaps records per species (this species within the purple bar). Fewer records (to the left) indicates a less abundant/encountered species while more records (to the right) indicates more abundant/encountered species.

Biology

Castes

Nomenclature

The following information is derived from Barry Bolton's Online Catalogue of the Ants of the World.

silaceum. Monomorium silaceum Heterick, 2001: 412, figs. 33, 130 (w.) AUSTRALIA (Queensland, Western Australia).
- Type-material: holotype worker, 15 paratype workers.
- Type-locality: holotype Australia: Queensland, Cloncurry, 7.vi.1936 (T. Greaves); paratypes: 2 workers with same data, 6 workers Queensland, Millungera Station, 31.v.1936, 1140 (T. Greaves), 4 workers Western Australia, N Kellerberrin, ii.1991, JDM’33’, vial 53, drawer 37 (A. Scougall), 3 workers Western Australia, Mt Whaleback, Newman, vii.1984, JDM’33’ (K.J. Walker).
- Type-depositories: ANIC (holotype), ANIC, BMNH, MCZC (paratypes).
- Status as species: Heterick, 2009: 159.
- Distribution: Australia.

Unless otherwise noted the text for the remainder of this section is reported from the publication that includes the original description.

Description

Worker

Holotype. HML 1.41; HL 0.53; HW 0.48; CeI 91; SI 0.40; SI 83; PW 0.26. Others. HML 1.34-1.62; HL 0.51-0.58; HW 0.44-0.57; CeI 86-98; SL 0.40-0.43; SI 73-84; PW 0.26-0.33 (12 workers).

As for the worker of Monomorium fieldi, but with the following apomorphies.

Head. Eye large, eye width greater than 1.5x greatest width of antennal scape. Frontal lobes parallel, sinuate. Venter of head capsule without elongate, basket-shaped setae.

Alitrunk. Promesonotal sculpture present in form of microreticulation and striolae on and around katepisternum, otherwise promesonotum smooth and shining; erect and suberect promesonotal setae 5-10; setulae appressed. Propodeal sculpture present as uniform microreticulation, with few or no striae or costulae; dorsal propodeal face sloping posteriad, with wedge-shaped flattening or shallow depression that is widest between propodeal angles. Lobes present as blunt flanges. Declivitous face ofpropodeum flat. Erect and suberect propodeal setae >5; propodeal setulae absent. Propodeal spiracle lateral and about midway between metanotal groove and declivitous face of propodeum.

Petiole and postpetiole. Petiolar node cuneate, dorsally rounded; sculpture absent, petiolar node smooth and shining. 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. Height ratio of petiole to postpetiole near 4:3.

General characters. Colour yellow. Worker caste monomorphic.

Type Material

Holotype, worker, Cloncurry, Queensland, Australia, T.G., ANIC32-015685, Australian National Insect Collection.
Paratype, 2 workers, Cloncurry, Queensland, Australia, Australian National Insect Collection.
Paratype, 3 workers, Millungera Stn., Queensland, Australia, Australian National Insect Collection.
Paratype, 3 workers, Mt Whaleback, Newman, Western Australia, Australia, Australian National Insect Collection.
Paratype, 4 workers, N of Kellerberrin, Western Australia, Australia, The Natural History Museum.
Paratype, 3 workers, Millungera Stn., Queensland, Australia, Museum of Comparative Zoology.

Etymology

Latin: “the color of yellow ochre”.

References

References based on Global Ant Biodiversity Informatics

Heterick B. E. 2001. Revision of the Australian ants of the genus Monomorium (Hymenoptera: Formicidae). Invertebrate Taxonomy 15: 353-459.
Heterick B. E., B. Durrant, and N. R. Gunawardene. 2010. The ant fauna of the Pilbara Bioregion, Western Australia. Records of the Western Australian Museum, Supplement 78: 157-167.