TWO DIFFERENT SPECIES OFEUGLENA,E. GENICULATAANDE. MYXOCYLINDRACEA(EUGLENOPHYCEAE), ARE VIRTUALLY GENETICALLY AND MORPHOLOGICALLY IDENTICAL1

Abstract

We investigated the similarity of a singleEuglena myxocylindraceastrain, isolated originally by Bold and MacEntee, to severalEuglena geniculatastrains on both morphological and DNA levels. We found the three DNA stretches, consisting of fragments coding for the parts of cytoplasmic and chloroplast small subunit rRNA, and the internal transcribed spacer (ITS2) of cytoplasmic rDNA, with the combined length of 4332 nucleotides, are identical inE. myxocylindraceaandE. geniculata, strain SAG 1224‐4b. Morphological differences betweenE. myxocylindraceaand anyE. geniculatastrain examined were well within the range ofE. geniculatavariability as well. The only difference behind the distinction ofE. myxocylindraceafromE. geniculatais the presence of the second chloroplast in the latter. However, we were able to induce the appearance of the second chloroplast in the cells ofE. myxocylindraceaand its disappearance in the cells ofE. geniculataby changing the composition of the culture media. We therefore conclude thatE. myxocylindraceaBold and MacEntee should be regarded as an environmental form ofE. geniculataDujardin. For the first time the morphology ofE. geniculatachloroplasts was shown as revealed by confocal laser microscopy.