New Species Creation?

Since we're talking speciation here, I was wondering if anybody entertains Lynn Margulis' idea that some speciation occured through symbiosis? I read her 'Acquiring Genomes' and she does not seem content with the Mayr formula of geographic speciation. Is there any recorded case of symbiotic speciation?Maybe I should try to confirm it myself on my animals. Termites have various bacterial and protist symbionts, could it be that different termite species have different symbionts, or, better yet, we could trace the evolution of termite species by comparing their gut contents?

By "species essentialism" maybe you mean the 'typological species concept'. The typological spcies concept distinguish between species of organisms by means of their 'type', which is influenced by Platonic philosophy. The assumption here is that the diversity between life-forms can be reduced to a number of distinct and immutable 'types' or 'essences'. It is believed that there are an 'ideal type' for each species, while all variations are deviations from the ideal type.The findings of natural history, and Darwinian variational evolution, put an end to species essentialism in biology generally. But some of its practices are still based on the essentialist assumption, for instance the designation of a holotype for new species description, or even 'The Human Genome Project'.