Termites

Like their hymenopteran cousins (ants, bees and wasps) termites (isopterans) live in colonies and divide labor among castes, produce overlapping generations, and take care of their young collectively. A typical colony contains nymphs (half-mature young), workers, soldiers, and reproductive individuals of both sexes, sometimes even several egg-laying queens.There are termite species that do not have a soldier caste at all, and they are fairly well represented in tropical regions of the world, especially South America and Africa. 

Workers take on the defense role by using their gut contents to either seal up nest damage, or trap invading ants which are the predominant invaders. At first glance, it may appear that this defensive method is inadequate, as casualties are often high on the termite’s side, especially in the event that a large breach has occurred and ants manage to invade in large numbers. However, most of these soldierless termite species feed on decaying wood or humus, and thereby largely avoid contact with ants while foraging. 

Species boundaries in termites are traditionally inferred by using morphological characters, although morphology sometimes fails to correctly delineate species. Another commonly used non-morphological taxonomic character is a profile of the cuticular hydrocarbons. They have been proved useful to distinguish a couple of insect species, especially among social insects. Using cuticular hydrocarbon profiles for species recognition is thought to be a direct way to compare the chemical characters through which social insects recognize each other. However, more recently researchers have taken advantage of alternative methods such as DNA Barcoding but nobody really tried using all of those methods simultaneously in an integrative taxonomic approach. 

An international group of researchers has now done this more extensive testing and their paper was published this week:

We sampled soldierless termites in various forest types of the Nouragues Nature Reserve, French Guiana. Our results show that morphological species determination generally matches DNA barcoding, which only suggests the existence of three cryptic species in the 31 morphological species. Among them, Longustitermes manni is the only species whose splitting is corroborated by ecological data, other widely distributed species being supported by DNA Barcoding. On the contrary, although cuticular hydrocarbon profiles provide a certain taxonomic signal, they often suggest inconsistent groupings which are not supported by other methods. Overall, our data support DNA Barcoding and morphology as two efficient methods to distinguish soldierless termite species.

The experienced barcoder is likely not surprised about how well COI sequences work to delineate soldierless termite species. It is remarkable though that cuticular hydrocarbon profiles are not very reliable although they have been portrait as representative for chemical cues the animals actually use to identify members of their own species. Probably there aren't as good as thought.