Ulnaria constricta-biseriata sp. nov., girdle view, SEM A a frustule with a collapsed hypovalve B–D details from A, note three copulae (labeled B1 to B3) associated with the epivalves and two rows of poroids present on B2 (wavy arrows) and B3 (arrows) E, F the apices with three copulae visible (labeled B1 to B3) associated with the epivalves and two rows of poroids produced on B2 (wavy arrow) and B3 (arrow). Scale bars: 20 μm (A); 3 μm (B–F).