The molecular characterization of the enigmatic dinoflagellate Kolkwitziella acuta reveals an affinity to the Excentrica section of the genus Protoperidinium
Mertens, K.N.; Takano, Y.; Yamaguchi, A.; Gu, H.; Bogus, K.; Kremp, A.; Bagheri, S.; Matishov, G.; Matsuoka, K. (2015). The molecular characterization of the enigmatic dinoflagellate Kolkwitziella acuta reveals an affinity to the Excentrica section of the genus Protoperidinium. Syst. Biodiv. 13(6): 829-844. dx.doi.org/10.1080/14772000.2015.1078855 In: Systematics and Biodiversity. Cambridge University Press: Cambridge. ISSN 1477-2000; e-ISSN 1478-0933, more |  |
| Keyword | | | Author keywords | brackish water; Caspian Sea; Finland; FTIR; phylogeny; single-cell PCR |
| Authors | | Top | - Mertens, K.N., more
- Takano, Y.
- Yamaguchi, A.
| | - Bagheri, S., more
- Matishov, G.
- Matsuoka, K.
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| Abstract | Kolkwitziella acuta is a cyst-forming dinoflagellate with a unique tabulation, occurring in freshwater to brackish environments of Eurasia and the USA. Based on the unique thecal plate arrangement, this species was previously interpreted as a missing link in the evolution between the genus Protoperidinium and the Diplopsalioideae. We isolated living K. acuta cysts from the south-western Caspian Sea and the central Baltic (Finland), and re-established the cyst-theca relationship. The cysts had a distinctive polar and dorsoventral compression and a characteristic wrinkly texture. The plate formula of the thecate stage was Po, X, 4′, 2a, 7′′, 3c+t, ?s, 5′′′, 1′′′′. Large subunit (LSU) and small subunit (SSU) ribosomal DNA sequences obtained through single-cell PCR of these cysts reveal that this species is close to Protoperidinum excentricum which belongs to the Excentrica section of the genus Protoperidinium. We suggest that it evolved from the genus Diplopsalis through a split of the apical and anterior intercalary plates. Furthermore, that the split of the antapical plates occurred several times independently in the evolution of Protoperidinium and Diplopsalioideae and is therefore a polyphyletic trait. The cyst of Kolkwitziella is considered an indicator of low salinities, specifically between 0 and 22 psu. Geochemical analysis of the cyst walls suggests a heterotrophic mode of nutrition. |
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