FIGURES 50–54 in A re-investigation of three Frenguelli's Caloneis taxa (Pinnulariaceae, Bacillariophyta) from Argentina

FIGURES 50–54. Caloneis mendosina Frenguelli (emend. Sar & Sunesen) from unmounted syntype material of C. quilinesis. SEM. Figs 50–51. Linear-panduriform valves with apiculate apices in internal view. Note the raphe is continuous at the central area and asymmetrical central nodule. Arrows show pseudosepta in figure 50. Fig. 52. Valve in lateral view showing valve mantle. Note terminal external raphe fissure finishing close to the valve margin (arrowhead). Fig. 53. Detail of the central nodule. Fig. 54. Detail of the apex of the valve in figure 51 showing a small helictoglossa (arrowhead) and a short pseudoseptum (arrow). Scale bar: 10 μm in Figs 50–52; 5 μm in Figs 53, 54.