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

Department of Medical Entomology, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
Department of Public Health and Health Promotion, College of Allied Health Science, Suan Sunandha Rajabhat University, Samut Songkhram 75000, Thailand
Office of Natural Science Research, National Science Museum, Technopolis, Khlong 5, Khlong Luang, Pathum Thani 12120, Thailand
Institut de Recherche pour le Développement (IRD), UMR INTERTRYP IRD-CIRAD, University of Montpellier, F-34398 Montpellier, France
Authors to whom correspondence should be addressed.
Insects 2022, 13(3), 287;
Received: 21 January 2022 / Revised: 1 March 2022 / Accepted: 8 March 2022 / Published: 14 March 2022
(This article belongs to the Section Other Arthropods and General Topics)
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.
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. View Full-Text
Keywords: outline morphometrics; Odontomachus monticola; O. rixosus; O. simillimus outline morphometrics; Odontomachus monticola; O. rixosus; O. simillimus
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MDPI and ACS Style

Samung, Y.; Chaiphongpachara, T.; Ruangsittichai, J.; Sriwichai, P.; Phayakkaphon, A.; Jaitrong, W.; Dujardin, J.-P.; Sumruayphol, S. Species Discrimination of Three Odontomachus (Formicidae: Ponerinae) Species in Thailand Using Outline Morphometrics. Insects 2022, 13, 287.

AMA Style

Samung Y, Chaiphongpachara T, Ruangsittichai J, Sriwichai P, Phayakkaphon A, Jaitrong W, Dujardin J-P, Sumruayphol S. Species Discrimination of Three Odontomachus (Formicidae: Ponerinae) Species in Thailand Using Outline Morphometrics. Insects. 2022; 13(3):287.

Chicago/Turabian Style

Samung, Yudthana, Tanawat Chaiphongpachara, Jiraporn Ruangsittichai, Patchara Sriwichai, Anon Phayakkaphon, Weeyawat Jaitrong, Jean-Pierre Dujardin, and Suchada Sumruayphol. 2022. "Species Discrimination of Three Odontomachus (Formicidae: Ponerinae) Species in Thailand Using Outline Morphometrics" Insects 13, no. 3: 287.

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