Key To Species

la. Valves linear or linearly elliptical to oval 2

lb. Valves broadly elliptical to lanceolate with slightly produced bluntly rounded apices, sternum distinct, narrow, and widening slightly near apices, cells solitary or in loose chains attached to particles (e. g. sand grains) D. surirella18 (Ehrenberg) G. W. Andrews

2a. Valves linear with rounded apices to slightly inflated in center, wide sternum, long chains, planktonic

D. karstenii^ (Boden) G. Fryxell in Fryxell & Miller

2 b. Valves linearly elliptical to broadly elliptical with broadly rounded apices, sternum variable in width, widening slightly near apices

D. surirelloidesn (Simonsen) G. W. Andrews

Distribution:

D. karstenii—warm water region—off southwest coast of Africa (Fryxell & Miller, 1981).

D. surirella—"cool to temperate seas" (Andrews, 1981), e.g., North Sea

(Drebes, 1974); Chile (Andrews Sc Rivera, 1987).

D. surirelloides—warm water region—Indian Ocean (Simonsen, 1974).

Genus Neodelphineis Takano 1982 (Plate 52, Table 64) Type: Neodelphineis pelagica Takano.

References: Taylor, 1967, p. 440, Plate 3, Figs. 22-24; Simonsen, 1974, p. 36, Plate 23, Figs. 8-18; Takano, 1982; Hernandez-Becerril, 1990; Takano, 1990, pp. 310-311; Round et al., 1990, p. 412; Hasle & Syvertsen, 1993, p. 309, Figs. 32-41. Tanimura 1992, p. 136, Fig. 13.

Generic characters:

Cells solitary or in zigzag or stellate chains.

Valve outline linear to broadly elliptical with broadly rostrate apices or inflated at the center and sometimes at the apices. Sternum narrow. Striae parallel to slightly radiate.

Single row of valve mantle areolae continues around apices. Usually one (occasionally two) fine pore near each apex (EM).

11 Basionyms: Zygoceros surirella Ehrenberg, Fragilaria karstenii Boden, and Rhaphoneis surirelloides Simonsen, respectively.

Toxarium undulatum

TABLE 64 Morphometric Data of Neodelphineis spp.

Apical axis Transapical axis Species (fi.m) (fi.m) Striae in 10|j.m

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