Hidden syndinian and perkinsid infections in dinoflagellate hosts

These parasites are abundant and ecologically important, but most species have been difficult to observe directly or cultivate, so our knowledge of them is usually restricted to environmental 18S rRNA gene sequences, and genome-scale molecular data are not available for most species.

Here, we report numerous syndinian parasites and one parasite that is sister to all known perkinsids from isolated single cells of diverse, free-living dinoflagellates. Of the 14 infected host cells collected, only five were noticeably infected via light microscopy at the time of collection. Single-cell transcriptome sequencing yielded relatively high transcriptomic coverage for parasites as well as their hosts.