Bibliographic Detail
Okamoto, N., Horák, A. & Keeling, P.J. , 2012
Reference:
Okamoto, N., Horák, A. & Keeling, P.J. (2012). Description of two species of early branching dinoflagellates, Psammosa pacifica n. g., n. sp. and P. atlantica n. sp.. PLoS ONE 7(6): 1-6 .
Notes:
PLoS ONE 7(6): e34900. doi:10.1371/journal.pone.0034900
Abstract:
In alveolate evolution, dinoflagellates have developed many unique features, including the cell that has epicone and
hypocone, the undulating transverse flagellum. However, it remains unclear how these features evolved. The early
branching dinoflagellates so far investigated such as Hematodinium, Amoebophrya and Oxyrrhis marina differ in many ways
from of core dinoflagellates, or dinokaryotes. Except those handful of well studied taxa, the vast majority of early branching
dinoflagellates are known only by environmental sequences, and remain enigmatic. In this study we describe two new
species of the early branching dinoflagellates, Psammosa pacifica n. g., n. sp. and P. atlantica n. sp. from marine intertidal
sandy beach. Molecular phylogeny of the small subunit (SSU) ribosomal RNA and Hsp90 gene places Psammosa spp. as an
early branch among the dinoflagellates. Morphologically (1) they lack the typical dinoflagellate epiconehypocone
structure, and (2) undulation in either flagella. Instead they display a mosa¨c of dinokaryotes traits, i.e. (3) presence of bipartite
trychocysts; Oxyrrhis marinalike traits, i.e. (4) presence of flagellar hairs, (5) presence of two-dimensional cobweb
scales ornamenting both flagella (6) transversal cell division; a trait shared with some syndineansand Parvilucifera spp. i.e. (7)
a nucleus with a conspicuous nucleolus and condensed chromatin distributed beneath the nuclear envelope; as well as
Perkinsus marinus -like features i.e. (8) separate ventral grooves where flagella emerge and (9) lacking dinoflagellate-type
undulating flagellum. Notably Psammosa retains an apical complex structure, which is shared between perkinsids,
colpodellids, chromerids and apicomplexans, but is not found in dinokaryotic dinoflagellates.
