Monomorium atomum procax Forel, 1911

Material examined. None available.

Material not physically examined. Syntype – CASENT0908766, ANTC31116 (MHNG) .

Literature. Type – Forel (1911) [as Monomorium (Martia) atomus var. procax]. Viehmeyer (1916), Overbeck (1924) [both as M. (Martia) atomus var. procax].

Localities. Bukit Timah Hill; Bukit Timah Road.

Habitat/Ecology. This species was found in primary or mature/old secondary forest, also in a garden, where colonies were collected from dead, hollowed-out (tree) branches.

Remarks. Type locality in Singapore. We do not have more recent physical material for reliable systematic assessment. Differences between M. atomum and its subspecies procax are also subtle and difficult to discern from type images on AntWeb. Nevertheless, we observed one striking difference: the propodeum in M. atomum is distinctly much longer than wide in dorsal view, whereas in M. atomum procax the propodeum is only slightly longer than wide. We maintain the subspecies procax for want of more compelling empirical evidence and material to support a raise in status to species.