Syvertsenia Witkowski & Gomes, 2013

Gomes, Ana, Witkowski, Andrzej, Dąbek, Przemysław, Boski, Tomasz, Moura, Delminda, Szkornik, Katie & Kurzydłowski, Krzysztof, 2013, Syvertsenia iberica (Cymatosiraceae): a new estuarine diatom genus characterized by the position of its process, Phytotaxa 142 (1), pp. 25-36 : 29

Syvertsenia Witkowski & Gomes gen. nov. ( Figs 2–19 )

Cells with one tubular process positioned in the central part of one of the valves mantle ( Figs 3, 4 , Figs 6–8 and Fig. 10 ). Valves linear with rostrate, protracted to distinctly set off, capitate apices. Valve face is flat, the valve mantle relatively steep and in general shallow. In the valve centre (internal view) the mantle bears a convex expansion within which a tubular process and a single adjacent areola are observed ( Figs 10, 12 and 13 ). The distribution of valve face areolae, which are probably closed with cribra, is approximately uniform/equidistant ( Figs 10, 15 ). No fascia, pseudoseptum, pili or apical spines have been observed.

= present, - = absent, + / - = present or absent, - / + = usually absent, Inc = incomplete). Adapted from Sabbe et al. (2010) and Hasle et

al. (1983).

Type species of the genus (designated here): ⎯ S yvertsenia iberica Witkowski & Gomes sp. nov. Etymology: ⎯The genus is named in honor of Dr. Erik E. Syvertsen distinguished Norwegian diatomologist and one of the authors of the family Cymatosiraceae .

Figures

FIGURES 2–9. Syvertsenia iberica. LM images. Figs 3–9: Specimens from the holotype slide. Figs 6, 7: Holotype specimen photographed in various techniques, note the presence of the tubular process on a mantle (arrow) Figs 8, 9: Same specimen photographed in various techniques. Figs 4–6 and 8: Phase contrast. Figs 7 and 9: Differential Interference Contrast. All scale bars = 10 µm.

FIGURES 10–19. Syvertsenia iberica. SEM images from the holotype sample (GS1) from Guadiana Estuary, Spain. Fig. 10: General view of the interior of the process valve. Note the tubular process (white arrow) and the presence of two linearly opposed ocelluli. Fig. 11: Close up to the valve internal view. Fig. 12: Close up of the middle part of the valve. Note the areolae occlusions, tubular process (black arrowhead) and mantle expansion with an areolae (white arrow). Fig. 13: Close up of the tubular process and areolae in the mantle expansion. Fig 14: Close up to the marginal spines. Fig. 15: Close up to the valve face areolae, which present an approximated linear and equidistant distribution. Figs 16, 17: Close up to the ocellulus, external (black arrowhead, Fig. 16) and internal (white arrow, Fig. 16) showing the presence of porelli (note the presence of spines in an external view). Figs 18, 19: Close up to the opposite apex ocellulus external view, note the presence of spines within ocellulus (black arrowhead, Fig. 18). Fig. 10: Scale bar = 10 µm. Fig. 11: Scale bar = 5 µm. Figs 12, 15 and 19: Scale bar = 500 nm. Fig. 13: Scale bar = 250 nm. Fig. 14: Scale bar = 200 nm. Fig. 16: Scale bar = 2 µm. Figs 17, 18: Scale bar = 1 µm.