Bibliographic Detail
Yoshida, M. Noël, M.H. Nakayama, T. Naganuma, T. & Inouye, I., 2006
Reference:
Yoshida, M. Noël, M.H. Nakayama, T. Naganuma, T. & Inouye, I. (2006). A haptophyte bearing siliceous scales: ultrastructure and phylogenetic position of Hyalolithus neolepis gen. et sp. nov. (Prymnesiophyceae, Haptophyta). Protist 157: 213-234.
Publication Date:
April 2006
Abstract:
A haptophyte alga bearing hyaline but conspicuous scales was discovered in surface water samples
of Shiribeshi Seamount, Japan. X-ray elemental analysis confirmed that silica was the major element
in these scales. These scales were hat-shaped, ellipsoidal in top view, 46lm wide and 57lm long,
perforated by several small pores, and were deposited on cells in several layers. Beneath the siliceous
scale layers, organic scales were present, which are typical of haptophytes. The cells were non-motile
despite having two short flagella hidden in the scale case. The haptonema, extended over the scale
case, and one and a half times the cell length. The intracellular features were typical of haptophytes,
including the peripheral endoplasmic reticulum (PER), Golgi cisternae with peculiar dilations, and the
flagellar apparatus. The siliceous scales were produced in vesicles in the posterior region of the cell.
Motile cells lacking silica scales were observed occasionally when cultures were maintained at lower
temperatures and under oligotrophic conditions. This alga was described as Hyalolithus neolepis gen.
et sp. nov. Phylogenetic analysis using the SSU rDNA and rbcL gene sequences indicated that
Hyalolithus is a member of the Prymnesiales and falls in a clade including Prymnesium, Platychrysis,
and Chrysochromulina polylepis. Based on these results, the evolutionary implications of the
presence of silicified scales in haptophytes is discussed.
