My research on folliculinids has found an undescribed species of Folliculinid with endosymbiotic dinoflagellates (most likely Symbiodidium sp).

This DIC image of a second generation Folliculina trophont only a few hours old is attached to the underside of a small 12mm floated coverslip in a petri dish. Endosymbiont dinoflagellates populate both the trophont and adjacent “swarmer”. Note the presence of dark granules of Hypericin-like pigments surrounding the trophont nucleus and the apical area of the”swarmer”. There are a number of papers on the Hypericin-Like pigments and Photophobic responces in the ciliates Stentor and Blepharisma (see below).

These dark granules have not been previously discribed in the Folliculinidae.

Possible adaptive advantages: 

  • This species of folliculinid live in shallow very clear waters where UV radiation penetrates to several metres. It is likely that the dark granules surrounding the trophont nucleus have evolved to reduce the mutagenic impact of UV on their DNA.
  • In the swarmer the Hypericin may be toxic to any predators.

ReferencesLobban et al. Photochemistry and Photobiology, 2007, 83:1074-1094 and Hanna FABCZAK, Acta Protozoologica 2000, 39: 171-181.)