Description of the first Oriental species of the ant genus Xymmer (Hymenoptera: Formicidae: Amblyoponinae).

The monotypic ant genus Xymmer Santschi, 1914 was established for X. muticus (Santschi, 1914) which has so far been known only from the West African subregion. The genus is easily distinguishable from the other amblyoponine genera by the anteromedian part of clypeus which is produced as a short rectangular lobe. Additional undescribed species had been found exclusively from Madagascar and Africa until recently. However, in March, 2015, a Xymmer colony was found in northern Central Vietnam. In the present paper Xymmer phungi sp. nov. is described as the first Oriental species of the genus. Although the worker of X. phungi is morphologically quite similar to that of X. muticus, the former is distinguishable from the latter by the following two characteristics of the worker: clypeal lobe 1/6 times as long as broad (vs. 1/3 times as long as broad in X. muticus); anterior margin of the lobe weakly concave (vs. almost straight in X. muticus). Xymmer phungi is well distinguished from Ethiopian Xymmer spp. for which 28S sequences are available from GenBank. Our observations suggest that the species feeds on geophilids (Chilopoda: Geophilomorpha). An updated key to Vietnamese genera of the subfamily Amblyoponinae is also provided.

The trap-jaw ant genus Odontomachus Latreille (Hymenoptera: Formicidae) from Sumatra, with a new species description.

The ant genus Odontomachus Latreille is reviewed for Sumatra, the sixth largest island in the world and located in western Indonesia. Previously three species were recorded from the island: O. simillimus F. Smith, O. rixosus F. Smith, and O. latidens Mayr. We add two species to the fauna, O. procerus Emery stat. nov and Odontomachus minangkabau sp. nov. The new species belongs to O. rixosus species group, and it is morphologically most similar to O. rixosus and O. pararixosus Terayama & Ito. However, it can be separated from the latter two by its large body (HL 3.13-3.55 mm, WL 4.15-4.65 mm), the masticatory margin with 11-14 denticles, and dark-colored body. Odontomachus latidens subsp. sumatranus Emery is newly synonymized with O. procerus. The castes and sexes of the known species are also described, including the first descriptions of the male for O. latidens, O. procerus, and O. rixosus. A key to the Sumatran species based on the worker caste is provided, and the bionomics of each species is summarized.