Ardissoneopsis fulgicans sp. nov. A, B valve in LM showing shape and striation (TK28) C pole of frustule from acid cleaned material in SEM, showing annulus (double-headed arrow) (J5) D, E poles of frustules in whole mounts, attached at opposite ends, showing girdle bands and apical spines (GU7R) F, G internal views of valve pole and central portion, showing the absence of pseudoseptum at pole and presence of longitudinal costae (arrows) (GU44N-A) H pole of valve with valvocopula, showing start of transverse costae (arrow) (contrast with pole of Synedrosphenia recta Fig. 13H); arrowhead indicates edge of fimbriate copula (J5) I, J poles of frustules showing fimbriae on copula and valvocopula, respectively (J5). Scale bars: 25 µm (A); 10 µm (D); 5 µm (B, C, E–J).