Description of the new species Kittonia kempii (Biddulphiales: Kittoniaceae) with comments on Kittonia hannai P. Lefébure & Chenevière and Kittonia gigantea (Greville) De Toni Author Sims, Pat A. 0000-0002-0214-8303 p. sims @ nhm. ac. uk; https: // orcid. org / 0000 - 0002 - 0214 - 8303 p.sims@nhm.ac.uk Author Williams, David M. 0000-0002-0584-307X d. m. williams @ nhm. ac. uk; https: // orcid. org / 0000 - 0002 - 0584 - 307 X d.m.williams@nhm.ac.uk text Phytotaxa 2022 2022-11-23 573 2 275 285 http://dx.doi.org/10.11646/phytotaxa.573.2.7 journal article 10.11646/phytotaxa.573.2.7 3fd5d86e-1214-4796-97df-fb30f3d2200f 1179-3163 7349988 Kittonia hannai P. Leféb. & Chenev. 1939: 23 , pl. 1, fig. 3 [= our Figure 8 ] ( Figs 8–20 ) Type :— USA . Moreno , California , USA ( Figs 8–20 ) Illustrations:— Long et al. 1946 : pl. 19, figs 6, 7; Brigger & Hanna 1965 : figs 2, 3 = Figures 10a and 10c , respectively); Cornell 1973: 1121 , text-fig. 2 (text-fig. 1 = ‘ Archaeomonadopsis incerta ’ Ramp 1940 [see Fig. 11b , reproduced from Ramp 1940: 63, fig. 3] = ‘broken processes of the biddulphoid diatom Kittonia hannai Lefébure & Chenevière’); Wornardt 1972 : pl.4, fig. l; Chambers (1997 : pl.14, figs 10, 11, Maastrichtian, Moreno Shale, BM 63885!, one specimen ). Valve face triangular with barely rounded apices and almost straight valve margins ( Figs 9, 12–14 ). Valve face probably slightly convex, weakly silicified specimens collapse ( Figs 9, 12–14 ). Valve centre circular, diameter ca. 10µm, hyaline. Valve surface covered with small granules ( Fig. 18 ). Marginal fold separates valve face from deep mantle ca. 15 µm lying beyond valve face ( Figs 9, 12–14 ). Tubular coiled process arises from circular hyaline area within angles of valve face, diameter ca. 12µm ( Figs 9, 12–14, 16, 19, 20 ), summit of club-shaped ( Fig. 15 ). Ocellus-like structure on surface of each summit, stalk pierced by occasional poroids (Fig. 15,19, 20). Areolae poroid, circular occluded by cribra arranged in rows radiating from valve centre to valve margin ca. 5 in 10µm ( Figs 14, 16–18 ); interstrial pores present. Single or double row of areolae present on valve margin appearing to lie vertically to mantle, margins ca. 6µm deep ( Figs 14, 16–18 ). Rimoportulae, 3–8, occurring within hyaline valve centre, exterior openings through short oval tube, interior an elongate slit between raised lips ( Figs 17, 18 ).