Ardissonea densistriata sp. nov. A holotype from Bikar Atoll, BA1 (LM) B, C external views of valves in SEM; arrows on B point to location of annulus (B Y42-1, C BA-1) D, E external view of two ends of same frustule showing isopolarity; arrow on E points to apical notch in VC (J5) F, G internal views of valves with one and two middle lines of foramina, arrows showing asymmetrical pseudoseptum on valve in F and asymmetrical pole of the valvocopula in G; arrowheads point to longitudinal costae (BA1) H, I external views of frustules from Bikar and Jaluit, respectively, showing profile of pole of valvocopula in H and apical comb of fimbriae on copula in I (arrow). Scale bars: 10 µm (A–C); 5 µm (D, E); 2.5 µm (F–I).