Maritime trap-jaw ants (Hymenoptera, Formicidae, Ponerinae) of the Indo-Australian region - redescription of Smith and description of a related new species from Singapore, including first descriptions of males.

The maritime trap-jaw ant Smith, 1859 is thought to be widespread throughout islands in the Indo-Pacific and parts of the Oriental realm. Because of its unique nesting preference for harsh littoral habitat and distinct morphology, has usually been assumed to consist of only one species. We, however, describe a new species similar to found in the mangroves of Singapore, Southeast Asia - . We find strong evidence of both species existing in (near) sympatry, and also distinct morphological differences between and the new species. Additional complementary DNA evidence in the form of COI barcodes (313 bp) supporting putative species identification and delimitation is provided. Defining morphological characteristics for the species group (nested within the larger clade) are given in detail for the first time. The worker and queen castes of the new species are described; a redescription of the worker caste of , based on specimens from Singapore and the Philippines in addition to the holotype, is also given. The males of both species are also described for the first time, including male genitalia. A preliminary key to most known species of the group based on the worker caste is provided.