Stephanodiscus neoaegypticus Flower, 2013

Flower, R. J., Keatings, K., Hamdan, M. A. & Hassan, F. A., 2013, Stephanodiscus Ehr. species from Holocene sediments in the Faiyum Depression (Middle Egypt), Phytotaxa 127 (1), pp. 66-80 : 72

Stephanodiscus neoaegypticus Flower sp. nov.

Cells circular, undulate, central areas weakly concave or convex, spines absent. Cell diameters c. 30–70 µm. Fascicles radial, uniseriate striae occupy about 2/3 of the valve radius with 3–4 rows of areolae at valve face-mantle junction. Interfascicles distinct, not raised (compared to fascicles), circa 1.5 µm wide around the mid radius, 4–5 areolae in 10 µm at valve margin. External areolar openings small (1 µm or less). Central area fultoportulae up to 6, near valve centre, with two satellite pores. Marginal fultoportulae with three satellite pores at termini of interfascicles. External openings of marginal fultoportulae slightly raised. Rimoportulae sub-marginal, 3–6, oblique, irregularly spaced.

Type:— EGYPT. Gharak: Faiyum Depression, 29.43447° N, 30.64213° E, Holocene lake sediment core ( GARK1 ) material, sediment depth 450 cm, collected April–May 2008, (Circled specimen ( Fig. 3 ) on slide BM 101659 ( BM!), holotype, designated here) .

Figures

FIGURES 3–8. Stephanodiscus neoaegypticus, LM. Fig. 3. Valve showing an indistinct sub-marginal hyaline ring and broad interfascicular ribs. Fig. 4. Valve focused to show the valve face-mantle zone with occasional bifurcating interfascicular ribs (arrowed). Fig. 5. A strongly silicified valve. Fig. 6. A part dissolved valve with eroded margin and diminished interfascicular ribs. Figs 7–8. S. neoaegypticus v. fekrii LM. Fig. 7. Whole valve focused to show the broad interfascicular ribs and marginal bifurcations (arrowed). Fig. 8. The same whole valve (Fig. 7) focused to show the central area. Scale bars = 5 µm (Figs 3–8)