FIGURES 20–31 in Nitella singaporensis (Charophyceae, Charales): new species and implications for the taxonomy of the genus Nitella

FIGURES 20–31. Nitella singaporensis from Singapore (isotype: LE), N. gracilis from Sicily (LE): 20 & 21—abbreviated central second segment (arrowhead), looking as an additional branchlet at first furcation; 21—rare case of 8 lateral secondary rays; 22—end parts of a branchlet with clearly visible central secondary ray (arrowhead); 23–25—2-celled dactyls, some of them appearing 1-celled after loss of end cell during storage in living state in the laboratory; 26—gametangia, [arrowhead—shortly stipitate antheridia, double arrowhead— production of antheridium in penultimate not end furcation], 27—oospore surface in LM, appearing as unclear reticulations, 28–30—stem nodes with easily visible nodal cell extruding from the base of branchlets below the whorl, resulting in nodal bulbil formation (30), 31—stem node of N. gracilis with nodal cell extruding from the base of branchlets and situated around it. Scale: 20–22—0.5 mm, 23–26, 28–31—0.2 mm, 27—20 μm. All photos by R. Romanov, except 26 by R.S.W. Yeo.