The cyst-motile stage relationship of three Protoperidinium species from south-east coast of Iran

Resting cyst and motile thecate cell stages of three heterotrophic Protoperidinium oblongum, Protoperidinium sp < b> and Protoperidinium claudicans were assessed. Cysts were isolated from sediment collected from southeast coast of Iran. Individual live cysts were incubated under optimal conditions for germination. Results showed that Protoperidinium oblongum cysts were pentagonal smooth walled and three cysts of this species were identified from Iranian sediment. The germinated cell of P. oblongum was colourless and elongated pentagonal in shape.  P. claudican theca cell has a pointed antapical horn with a four sided apical plate. Protoperidinium sp. had dark brown pentagonal cyst. Its germinated cell differed from other Protoperidinium species. Two divergent distally antapical horns formed 90˚ between the horn and Posterio-lateral of main body edge, thus, comprising a unique species in the Protoperidinium genus. This kind of antapical horn has not been previously reported among Protoperidinium spp.