Telling apart identical ant species that behave totally different!

What is it about?

This is an interdisciplinary study. There are weaver ants in South America building large colonies up the tree canopies. Also there are some ground-foraging semi-nomadic ants settling small nests in just any available crevice, including abandoned termite nests. Problem is: two of the main species in such radically different groups of ants look (almost) identical, and have been known under the same name, for decades! These are Camponotus textor and Camponotus senex. Most specialists find them very difficult, if ever possible, to visually differentiate. This paper takes a deeper look into the overlapping morphology of the two sibling species, and emphasises on their differences that can be used to tell one from the other. In reality, some noticeable patterns of colour and body hairs are useful in telling between the species in our samples and among deposited museum specimens. Furthermore , the larvae of the two species have a different hair (the longest ones, on their back) that has a different tip. Still, such characters rely on some magnification lenses and background experience with ants morphology. Other specialists can find their way as below: The analyses further demonstrate marked chemical differences between the adults of the two ant species, regarding cuticular waxes and venom composition. This would enable chemical ecologists handling fresh or live specimens in differentiating between the seemingly identical ants. Finally we present some genetic fingerprints that can be used in barcoding the different ants, which are readily accessible to molecular biologists who would rather avoid ant morphology or chemical analyses. The genetic imprints obtained by PCR were also compared with a large number of sequences from other species, providing a preliminary phylogeny tree. Curiously, although the two ant species are remarkably similar, they are not genetically closely related like sister species. This agrees with their radically different biology in supporting the hypotheses that their morphological similarity results of convergence, and as such, is merely skin-deep.

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Why is it important?

Sibling species are a major challenge for the study of ants. Telling between different species is basic for any biological investigation, and the number of exceedingly similar ant species is currently beyond guess. In delineating a multidisciplinary approach to sibling species, this study proposes novel ways the problem could be approached by other scientists facing the same dilemma. The described methods are trivial, and easily replicable. We expect colleagues from different disciplines to be able to apply a similar approach, and see whether it proves helpful. Moreover in presenting new resources to sort between these two related ants we hope to have encouraged further research into South American weaver ants. These are fairly common ants of significant local (cultural & ecological) importance which are largely lacking in dedicated studies.

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