Cardiocondyla sp.4 .of.SKY (*excluded from official named species count)

Material examined. Queens and workers, Central Catchment Nature Reserve, 4 Sep 2017, W. Wang leg., WW-SG17-020, ZRC _HYM_0001757; queens and workers, Mandai forest, 15 Jan 2020, W. Wang leg., WW-SG20-001, ZRC _ ENT00014129 ; Kranji Road, 7 Sep 2016, G.W. Yong leg., ZRC _ ENT00048406 .

Localities. Central Catchment Nature Reserve; Kranji Road; Mandai.

Habitat/Ecology. This species appears to be associated mostly with mature and/or old secondary forests. Nests were found in cavities in bark of large fallen trees, or in fallen wood on ground.

Remarks. Though currently undescribed, this unique species is given special mention here as it appears quite common not just in Singapore, but in Borneo and throughout South Thailand (Sk. Yamane 2020, pers. comm.). Body generally uniformly dark brown, almost entirely coarsely rugose-reticulate except for the gaster which is smooth and shining. This species appears affiliated to Cardiocondyla thoracica (Smith, 1859), or is at least in the same species group, based on similar features such as: 1) anterior margin of pronotal disc slightly elevated and projecting above the otherwise (near) continuous convex outline of the mesosomal dorsum in profile, 2) metanotal groove indistinct or almost absent, and 3) very long propodeal spines with apices directed posteriorly.