Specimens of Sceptroneis cuneata from Grunow’s Honduras sample A–C whole frustule at 0° tilt and details of basal pole and apical poles, respectively, showing internal costae and the copula; arrows point to long fimbriae overlapping valvocopula at both poles D, E same specimen, tilt = 60°, details of apical and basal poles, respectively, showing copula, including shallow cut-away matching smaller pleura (arrow on D), hyaline abvalvar margin of copula (black arrow on D), and reduced poration near basal pole (arrow on E) F apical part of valve in external view G valvocopula associated with same specimen. Scale bars: 50 µm (A); 10 µm (B–F); 5 µm (G).