Timothy R. C. Lee

The origins and radiation of Australian Coptotermes termites: from rainforest to desert dwellers.

The termite genus Coptotermes (Rhinotermitidae) is found in Asia, Africa, Central/South America and Australia, with greatest diversity in Asia. Some Coptotermes species are amongst the worlds most damaging invasive termites, but the genus is also significant for containing the most sophisticated mound-building termites outside the family Termitidae. These mound-building Coptotermes occur only in Australia. Despite its economic and evolutionary significance, the biogeographic history of the genus has not been well investigated, nor has the evolution of the Australian mound-building species. We present here the first phylogeny of the Australian Coptotermes to include representatives from all described species. We combined our new data with previously generated data to estimate the first phylogeny to include representatives from all continents where the genus is found. We also present the first estimation of divergence dates during the evolution of the genus. We found the Australian Coptotermes to be monophyletic and most closely related to the Asian Coptotermes, with considerable genetic diversity in some Australian taxa possibly representing undescribed species. The Australian mound-building species did not form a monophyletic clade. Our ancestral state reconstruction analysis indicated that the ancestral Australian Coptotermes was likely to have been a tree nester, and that mound-building behaviour has arisen multiple times. The Australian Coptotermes were found to have diversified ∼13million years ago, which plausibly matches with the narrowing of the Arafura Sea allowing Asian taxa to cross into Australia. The first diverging Coptotermes group was found to be African, casting doubt on the previously raised hypothesis that the genus has an Asian origin.

Presoldier differentiation of Australian termite species induced by juvenile hormone analogues

Termite soldiers have species‐specific defensive morphologies. High juvenile hormone (JH) titre is required for workers to moult into presoldiers (intermediates between workers and soldiers). Artificial inductions of presoldiers using JH or JH analogues (JHAs) have been conducted in many species, but levels of intergeneric and species‐specific JH sensitivity are not clear. Here, we investigated mortality and presoldier induction rates after the same JHA treatments in three Australian termites: the rhinotermitids Coptotermes lacteus and Schedorhinotermes intermedius, and the early branching termite species Mastotermes darwiniensis. Induced presoldiers, especially in S. intermedius (soldiers with labral brush‐like weapons), were used for the observation of outer morphologies using scanning electron microscopy. In C. lacteus, large numbers of presoldiers were induced by all JHAs examined, and the mortality rate of workers was quite high. On the other hand, presoldier induction rates were very low in S. intermedius and zero in M. darwiniensis. However, mortality rates of these two species were quite different. In M. darwiniensis, the numbers of dead individuals in almost all JHA‐treated dishes were not significantly different from those of an acetone control. These results suggest that JHA sensitivity might be quite different among the three species, although further analyses using multiple colonies are needed to confirm this possibility. Scanning electron microscopy observation in S. intermedius showed that soldier‐specific formations of frontal pores in the heads, including a median furrow running from the frontal pore to the apical part of the labrum, and many campaniform sensillae and short bristles at the end of the labrum were all initiated at the presoldier stage.

A review of the status of Coptotermes (Isoptera : Rhinotermitidae) species in Australia with the description of two new small termite species from northern and eastern Australia

Abstract. Integrative taxonomy, including molecular, morphological, distributional and biological data, is applied in a review of the taxonomy of the Australian species of the pest termite genus Coptotermes. The validity of the previously described species is discussed, and two new species, Coptotermes nanus, sp. nov. and Coptotermes cooloola, sp. nov., are described from the Kimberley region of Western Australia and south-east Queensland respectively. Their delimitation is based on morphological and distributional data, and the results of generalised mixed Yule-coalescent analysis of mitochondrial DNA sequence data. Images of the external view of the two new species are provided, as well as a key, based on soldier characters, for all Australian species of Coptotermes.

Female-only workers and soldiers in Schedorhinotermes intermedius are not produced by parthenogenesis

Termites differ from hymenopteran social insects in several important respects, perhaps most significantly in their sex and caste determination systems: while hymenopteran colonies are female dominated (and sex determination is haplo-diploid), termite colonies are usually split evenly between males and females (and sex determination is through sex chromosomes). Not all termite species have an equal sex ratio—in the termite genus Schedorhinotermes, almost all workers and soldiers are females. The mechanism maintaining this sex ratio skew is unknown, but a possible mechanism (known in other termites as a mechanism for producing reproductives) is parthenogenesis. Under this scenario, soldiers and workers would be offspring of the queen only. In this study, we performed microsatellite analysis on 11 colonies of Schedorhinotermes intermedius (Isoptera: Rhinotermitidae) to investigate the parentage of workers, soldiers and alates within colonies, and to determine whether parthenogenesis is responsible for the production of female workers and soldiers. We also conducted a preliminary analysis of population and colony genetic structure. We found that females from a single colony had in some instances more than two alleles among them at a single microsatellite locus. This indicates that a single female cannot be producing these offspring, as she has a maximum of two different alleles at any locus, ruling out the possibility that the high proportion of females in this species comes about through parthenogenesis.