The parabasalid symbiont community of Heterotermes aureus: Molecular and morphological characterization of four new species and reestablishment of the genus Cononympha

The subterranean termite Heterotermes aureus is endemic to arid regions of southwestern USA and northern Mexico. Like other termites in the family Rhinotermitidae, it harbors a community of protists (Phylum Parabasalia) in its hindgut that aid in cellulose digestion. We investigated the hindgut community of H. aureus using light microscopy, single cell isolation, and high throughput amplicon sequencing. Here we describe four new parabasalid species from the classes Trichonymphea and Spirotrichonymphea. Three of the new species include Pseudotrichonympha aurea (Trichonymphea), Holomastigotoides aureus, and Holomastigotoides oxyrhynchus (Spirotrichonymphea). The fourth new species is a Spirotrichonympha-like protist for which we reinstate the genus Cononympha and describe under the name Cononympha aurea (Spirotrichonymphea). We also used high throughput amplicon sequencing with custom primers on DNA from fresh and ethanol preserved termites collected across the southwest USA and Mexico to investigate population-level differences in hindgut community composition. We report that the community is highly similar across populations: no additional parabasalid species were identified in any of the H. aureus specimens, but several specimens appeared to lack either C. aurea or H. oxyrhynchus.