Chromophyton vischeri (Chrysophyceae) occurring from mud samples of Lake Izunuma

Abstract

The bloom of “Hikarimo” was recorded from mud samples collected from Lake Izunuma. Morphological features observed under light microscope showed the Chrysophycean algae having golden colored floating and motile cells. The motile cells had long and short flagella at the tip of the cell, and a single cup-shaped chloroplast with a semi-embedded pyrenoid. These morphological features were consistent with those of Chromophyton vischeri (= Ochromonas vischeri). We determined the nucleotide sequence of the 18SrRNA gene from isolates, and compared it with known sequences. The obtained sequence showed 99.9% similarity to C. cf. rosanofii CCMP2751. Although we have not observed a bloom of “Hikarimo” in the field yet, Lake Izunuma might be a northern limit of distribution of C. vischeri in Japan.