Chrysochromulina palpebralis sp. nov. (Prymnesiophyceae): a haptophyte, possessing two alternative morphologies

摘要

A marine haptophyte flagellate, Chrysochromulina palpebralis sp. nov., is described from cultures originating from the Nervión River estuary in the Cantabrian Sea, northern Spain. In addition, cultures of similar organisms originating from Japanese and South African waters have been studied. Cells of C. palpebralis had an ovoid shape with an anterior shoulder and were 8–13 µm long and 6–9 µm wide. The cells possessed two equal to subequal flagella that measured 20–27 µm and a haptonema (7–15 µm long) that was flexible and shorter than the flagella. The life cycle included two motile cell forms indistinguishable at the light microscope level. At the electron microscope level, the two cell forms could be distinguished by having different types of body scales. Flow cytometric ploidy analysis showed that the nuclei of the two forms differ in DNA content by a factor of about four. One cell form, f. palpebralis, assumed to be tetraploid, was covered by three scale types, one with a central spiny projection and a peripheral rim with about 20 projections and two types of ovoid plate scales. The other form, f. bisquamata, assumed to be haploid, had two types of plate scales. The first cell form is known from the literature as ‘eyelash Chrysochromulina’ and has previously been recorded from coastal waters in Australia, Japan and South Africa. Phylogenetic analyses based on the nuclear encoded SSU and LSU ribosomal DNA sequences suggest that C. palpebralis is closely related to some nonsaddle-shaped Chrysochromulina species, clustering with C. polylepis and C. kappa as its closest relatives. Chrysochromulina palpebralis was nontoxic to nauplii of brine shrimp.