Polyrhachis lachesis

Polyrhachis lachesis inhabits open eucalypt forests and savannah woodlands, seemingly preferring bare ground without a grass cover as their nesting sites. It is not a very common species which occurs from Lakefield on Cape York Peninsula, south to about Gladstone.

Identification
Polyrhachis lachesis is very similar to Polyrhachis paxilla, with most distinguishing characters given under the latter species. It is also relatively close to Polyrhachis schenkii and it seems that Forel originally considered P. lachesis to be a subspecies of the latter (the original labels on syntype specimens read ‘P. Schenki For. r. Lachesis For.’). However, they are are easily separated by differences in their size (HL 1.31-1.56 in P. schenkii versus 1.84-1.96 in P. lachesis), 210-250 in P. schenkii versus 160-185 in P. lachesis) and the outline of the pronotal humeri that, in P. lachesis, are produced into dilated, dorsally shallowly concave, rounded prominences (Fig. 12A), while they are narrowly rounded or subangular in P. schenkii (Fig. 12G).

Distribution based on Regional Taxon Lists
Australasian Region: Australia.

Nomenclature

 *  lachesis. Polyrhachis lachesis Forel, in Emery, 1897d: 582 (footnote) (w.) AUSTRALIA. Combination in P. (Hagiomyrma): Emery, 1925b: 185.

Additional References

 * Kohout, R.J. 2013. Revision of Polyrhachis (Hagiomyrma) Wheeler, 1911 (Insecta: Hymenoptera: Formicidae: Formicinae). Memoirs of the Queensland Museum, Nature 56, 487-577.