An updated checklist of the ants of Thailand (Hymenoptera, Formicidae)

The Leptogenys Roger, 1861 (Formicidae, Ponerinae) of Hong Kong SAR with additional records from Guangdong, China

Leptogenys is the most diverse genus of the ant subfamily Ponerinae and is widely distributed across the world's tropical and subtropical regions. More than 40 species are known from the Oriental realm displaying a wide range of ecologies, although their life history traits remain poorly understood, and new species are frequently discovered. Here, a faunal review of the genus from Hong Kong SAR, southern China is provided. A total of nine species are recorded, with one new species, Leptogenysgrohli Hamer, Lee & Guénard, sp. nov. described. Ecological and biogeographic information, including new information on reproductive modes for two species are provided with the ergatoids of L.binghamii Forel, 1900 and L.rufidaZhou et al., 2012 described. Additional records for five of these species within the neighbouring province of Guangdong are also provided. Finally, an illustrated key to species known from Hong Kong is presented, as well as notes on each species' distribution, ecology, and behaviour. An updated provincial distributional checklist of the Leptogenys species of Mainland China and Taiwan is also supplied.

The ant subgenus Campomyrma of the genus Polyrhachis Smith, 1857 (Hymenoptera, Formicidae, Formicinae) in Thailand and Laos, with descriptions of two new species

The subgenus Campomyrma Wheeler, 1911 of the genus Polyrhachis Smith, 1758 in Thailand and Laos is reviewed. Four species are recognized, of which two are described and illustrated as new to science based on the worker and dealate queen under the names Polyrhachis quadrispinosa Jaitrong & Noon-anant, sp. nov. (found in a dead twig on a rubber tree) and P. lao Jaitrong & Yamane, sp. nov. (collected in dead wood). Polyrhachis sukarmani Kohout, 2007 is recorded for the first time from Thailand. A key to the Thai and Lao species of the subgenus based on the worker caste is given.

A new species of the ant Platythyreaclypeata species group (Hymenoptera, Formicidae, Ponerinae) from continental Asia

The Platythyreaclypeata species group is reviewed and three species, including one new species, P.homasawini sp. nov., are recognized. This species group is distinguished from the P.parallela species group by the reddish-brown body, the elliptical shape of the propodeal spiracle, the elongate antennal scape, and the distinctly narrowed posteriad space between frontal carinae. Platythyreahomasawini sp. nov., from Thailand and China, is described based on the worker caste. The type series of the new species was collected on the forest floor from dead wood in an advanced stage of decomposition. A key to the Oriental species of the genus Platythyrea based on the worker caste is provided.

Species Discrimination of Three Odontomachus (Formicidae: Ponerinae) Species in Thailand Using Outline Morphometrics

Simple Summary

Determination of species in the ant genus Odontomachus, which is a venomous group of ants, may require the use of highly trained entomologists. In Thailand, three species are very similar and difficult to distinguish: O. monticola, O. rixosus, and O. simillimus. In such a situation, a complementary technique not requiring highly specialized entomological knowledge is welcome. The geometric morphometric approach has proven to be this sort of tool, especially powerful for morphologically close or even cryptic species. In its most recent development, the geometric method uses the relative position of some anatomical landmarks. However, in worker ants these landmarks are few in number and can be difficult to assess without dissection. Here, therefore, we use the outline-based approach, an alternative geometric technique that has not yet been tested in ants. We show that the simple outline of the head contains a strong taxonomic signal, much stronger than the one obtained from the pronotum shape. The outline technique therefore represents a promising approach to aid in the determination of ant species.

Abstract

All members of the ant genus Odontomachus Latreille, 1804 are venomous ants. Four species in this genus have been identified from Thailand: Odontomachus latidens Mayr, 1867; O. monticola Emery, 1892; O. rixosus Smith, 1757; and O. simillimus Smith, 1758. The three latter species are available and have been used for an outline morphometric study. They display similar morphology, which makes their distinction very difficult except for highly qualified individuals. A total of 80 worker specimens were studied, exploring the contour shapes of their head and pronotum as possible taxonomic characters. The size of each body part was estimated determining the contour perimeter, the values for which were largely overlapping between O. rixosus and O. simillimus; most O. monticola specimens exhibited a significantly larger size. In contrast to the size, each contour shape of the head or pronotum established O. rixosus as the most distinct species. An exploratory data analysis disclosed the higher taxonomic signal of the head contour relative to the pronotum one. The scores obtained for validated reclassification were much better for the head (99%) than for the pronotum (82%). This study supports outline morphometrics of the head as a promising approach to contribute to the morphological identification of ant species, at least for monomorphic workers.