Cyst–theca relationship of the arctic dinoflagellate cyst Islandinium minutum (Dinophyceae) and phylogenetic position based on SSU rDNA and LSU rDNA

• Published in: Journal of Phycology
• Main Authors: Potvin, Éric, Rochon, André, Lovejoy, Connie
• Other Authors: Vaulot, D., Fonds de Recherche du Québec - Nature et Technologies awarded to Éric Potvin, Natural Sciences and Engineering Research Council, Northern Scientific Training
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2013
• Subjects: Arctic; Sea ice
• Online Access: http://dx.doi.org/10.1111/jpy.12089; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fjpy.12089; https://onlinelibrary.wiley.com/doi/pdf/10.1111/jpy.12089

Round brown spiny cysts constitute a morphological group common in high latitude dinoflagellate cyst assemblages. The dinoflagellate cyst I slandinium minutum (Harland et Reid) Head, Harland et Matthiessen is the main paleoecological indicator of seasonal sea‐ice cover in the Arctic. Despite the importance of this cyst in paleoceanographical studies, its biological affinity has so far been unknown. The biological affinity of the species I . minutum and its phylogenetic position based on the small subunit ribosomal RNA gene ( SSU rDNA ) and the large subunit ribosomal RNA gene ( LSU rDNA ) were established from cyst incubation experiments in controlled conditions, optical and scanning electron microscopy, and single‐cell PCR . The thecal motile cell obtained was undescribed. Although the motile cell was similar to A rchaeperidinium minutum (Kofoid) Jörgensen, the motile cell of I . minutum lacked a transitional plate in the cingular series, which is present in A rchaeperidinium spp. I slandinium minutum and A rchaeperidinium spp. were paraphyletic in all phylogenetic analyses. Furthermore, P rotoperidinium tricingulatum , which also lacks a transitional plate, was closely related to I . minutum and transfered to the genus I slandinium . Based on available data, it is clear that I slandinium is distinct from A rchaeperidinium . Therefore, we considered I slandinium Head, Harland et Matthiessen as a non‐fossil genus and emend its description, as well as the species I . minutum . This is the first description of a cyst–theca relationship and the first study that reports molecular data based on SSU rDNA and LSU rDNA on a species assigned to the genus I slandinium .