2026/05/04 by Kyoko Hagino, Yoshihito Takano, Kevin C. Wakeman +19
Earth and Planetary Sciences · Environmental Science · #Aquatic Ecosystems and Phytoplankton Dynamics #Marine and coastal ecosystems #Marine and coastal plant biology
paper · doi:10.1080/00318884.2026.2660260
crossref issued 2026/05/04 · crossref published 2026/05/04 · crossref published-print 2026/05/04 · openalex publication_date 2026/05/04 · crossref published-online 2026/06/03 · crossref created 2026/06/03 · openalex created_date 2026/06/04 · crossref deposited 2026/07/27 · crossref indexed 2026/07/27 · openalex updated_date 2026/07/28
Braarudosphaera bigelowii is a marine coccolithophorid characterized by pentagonal calcareous plates called pentaliths. It has been regarded as a species complex comprising multiple species that can be distinguished from each other based on the size of pentaliths and 18S rRNA gene sequences. Chrysochromulina parkeae, a marine haptophyte, was once considered an independent species, but now is known to be a part of the life cycle stages of any one of the species of the B. bigelowii species complex. However, the formal taxonomy of these species complexes has not been reevaluated. This study examined relationships among sizes of cell, pentaliths and organic scales, nuclear 18S rRNA gene sequences, and nifH and 16S rRNA gene sequences of nitroplasts in the B. bigelowii species complex. Our results showed that the size of cells, pentaliths and scales differed among different sequence types, and are useful for classification of Braarudosphaera. The definition of B. bigelowii sensu stricto (s.s.) was emended, and the morphotypes Intermediate Form-A was raised to the species rank as Braarudosphaera okadae sp. nov. The cell and scale sizes of 18S type IV strain were larger than those of B. bigelowii s.s. strains (18S type III) and overlapped to those of C. parkeae holotype. Therefore, 18S type IV and C. parkeae are considered as conspecific, and a new combination, Braarudosphaera parkeae comb. nov. is proposed.