Variation in filament width and gas vesicles of red and green isolates of Planktothrix spp

摘要: Species of Oscillatoria with abundant gas vesicles have been reclassified in the genus Planktothrix and names species distinguished partly by differences pigmentation filament width retained new combinations. We determined variation (d f ) vesicle critical pressure (P c three collections spp.: 56 green coloured isolates (P. agardhii) 32 red rubescens) from Blelham Tarn, a shallow lake English Lake District; 19 P. rubescens Zurich, deep Switzerland; 25 15 21 Nordic lakes NIVA collection. The width, which occur populations different lakes, are culture. difficulty using d to distinguish taxa is that it forms normally distributed continuum. mean pressures form discontinuous distribution (with peaks at about 0.7, 0.9 1.1 MPa) correlated GV genotype groups (GU5/6, GV2/4 GV3, respectively). p not useful taxonomic character: full range encountered strains do differ other respects. Though quantitative data lacking, has proposed depth: MPa found only Zurich; 0.7 Tarn. presence (red isolates) or absence (green phycoerythrin was stable cultures maintained over many generations.