Crematogaster treubi Emery, 1896

Material examined. Bukit Timah Nature Reserve, 1.35499, 103.78167, 19 Jul 2017, W. Wang leg., ZRC _ ENT00047931; I-cube building (NUS), 1.293472, 103.77633, 1-8 Apr 2015, M.S. Foo & W. Wang leg., malaise trap, ZRC _ BDP0045999; Lower Peirce Reservoir, Aug 1990, collector unknown, ZRC _ ENT00000144; Pulau Semakau New Fragment, Apr-Oct 2012, J. Puniamoorthy et al. leg., mangroves, malaise trap, ZRC _BDP (multiple); Pulau Ubin, Apr-Oct 2012, J. Puniamoorthy et al. leg., mangroves, malaise trap, ZRC _BDP (multiple); same locality as previous, 7 Jan 2014, Sk. Yamane leg., ZRC _HYM_0000368-370; Sungei Buloh Wetland Reserve, Apr-Oct 2012, J. Puniamoorthy et al. leg., malaise trap, ZRC _BDP (multiple); same locality as previous, 1.44632, 103.73057, 5 Dec 2018, W. Wang leg., ZRC _ ENT00007638; Sunset Way, 1.32609, 103.77187, 23 Sep 2016, G.W. Yong leg., ZRC _HYM_0001765; Upper Peirce Reservoir, 10 Jan 2014, Sk. Yamane leg., ZRC _ HYM_0000371-374 .

Material not physically examined. Queens, FOCOL1632-1633 (ZMHB) [types of Crematogaster millardi] .

Literature. Viehmeyer (1916), Overbeck (1924) [both as C. millardi]. Wang et al. (2018a).

Localities. Bukit Timah Nature Reserve; Bukit Timah Road; I-cube building (NUS); Lower and Upper Peirce Reservoir; Pulau Semakau New Fragment; Pulau Ubin; Sungei Buloh Wetland Reserve; Sunset Way.

Habitat/Ecology. This species is associated mostly with young or mature secondary forests in Singapore, including abandoned plantation forest and other disturbed fragments in urban or semi-urban settings. These ants have also been found in mangroves, nesting in mangrove tree trunks or foraging on Thalassina (mud lobster) mounds.

Remarks. This species was first recorded from Singapore as types of ‘ C. millardi ’ (Viehmeyer 1916); the latter species was synonymized as a junior synonym of C. treubi by Hosoishi & Ogata (2012).