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* Mentioned in the text for comparison. ' ?, Data uncertain.

poroids in a varying number of rows or one row of more square poroids. These narrower Pseudo-nitzschia species are, like the larger ones, almost indistinguishable in girdle view and have most likely often been confused with N. delicatissima as the best known of the complex.

1. Circular poroids; central larger interspace present.

Pseudo-tiitzschia delicatissima (Cleve) Heiden in Heiden & Kolbe (Plate 72, Table 75)

Basionym: Nitzschia delicatissima Cleve. Synonym: Nitzschia actydrophila Hasle.

References: Cleve, 1897a, p. 24, Plate 2, Fig. 22; Heiden &c Kolbe, 1928, p. 672; Hasle, 1965b, p. 35, Plate 2, Fig. 10, Plate 15, Figs. 19-23; Hasle, 1976b, p. 102, Figs 1-5; Hasle & Medlin, 1990c, p. 169, Plate 22.5, Figs. 19-23; Hasle et al., 1996, Figs. 23-25 and 70-75. Girdle view: Linear; cells slightly sigmoid, narrow, and truncated; overlap of cells in chains short (about one-ninth of cell length). Valve view: Spindle shaped with slightly rounded apices. Fibulae and central larger interspaces barely visible with LM. Striae with two rows of poroids (TEM).

Remarks: Pseudo-tiitzschia pseudodelicatissima and P. delicatissima are readily distinguished by their stria structure resolved with EM. The distinction is harder to recognize with LM. The more pointed cell ends in girdle view, the more tapering valve ends, and the more linear valve outline of P. pseudodelicatissima compared to P. delicatissima do help to ascertain the identification of the two species.

Pseudo-nitzschia litieola (Cleve) Hasle (Plate 71, Table 75) Basionym: Nitzschia litieola Cleve. Synonym: Nitzschia barkleyi Hustedt.

References: Cleve, 1897b, p. 300, Fig. 10; Hustedt, 1952, p. 293, Figs. 13 and 14; Hasle, 1965b, p. 29, Plate 12, Figs. 15-19; Simonsen, 1974, p. 53, Plate 39, Figs. 4-6; Hasle & Medlin, 1990c, p. 169, Plate 22.3, Figs. 15-21; Hasle, 1993, p. 319. Girdle view: Linear to slightly lanceolate with pointed, somewhat sigmoid ends; overlap of cell ends in chains one-fifth to one-sixth of cell length. Valve view: Linear with slightly pointed apices. Fibulae coarse; striae with one, and in parts of the valve two, rows of porioids (TEM), punctate when examined with LM.

Pseudo-nitzschia prolongatoides (Hasle) Hasle (Plate 73, Table 75) Basionym: Nitzschia prolongatoides Hasle.

Synonym: Nitzschia prolongata Manguin non Nitzschia prolongata Hustedt (see Hasle, 1965b, p. 27).

P. turgidula

P. cuspidata

References: Manguin, 1957, p. 132, Plate 7, Fig. 46; Hasle, 1965b, p. 25, Plate 2, Fig. 11, Plate 12, Figs. 7 and 8; Hasle 8c Medlin, 1990c, p. 169, Plate 22.3, Figs. 7 and 8; Hasle, 1993, p. 319. Girdle view: Almost linear, possibly expanded in the middle; overlap of cell ends extremely short (about 1/15 of cell length). Valve view: Expanded middle part occupying about one-third of cell length; rostrate parts with slightly wider apices. Fibulae, central larger interspace with central nodule, and delicate transverse interstriae discernible with LM. Striae with two to three rows of circular poroids resolved with TEM.

Pseudo-nitzschia turgidula (Hustedt) Hasle (Plate 71, Table 75) Basionym: Nitzschia turgidula Hustedt.

References: Hustedt, 1958a, p. 182, Figs. 172 and 173; Hasle, 1965b, p. 24, Plate 1, Fig. 11, Plate 2, Fig. 3, Plate 12, Figs. 1-6; Hasle 8c Medlin, 1990c, p. 169, Plate 22.3, Figs. 1-6; Hasle 1993, pp. 320. Girdle view: Margins slightly convex tapering toward truncated cell ends; overlap of cells in chains short, about one-sixth of cell length. Valve view: Larger specimens linear except for a middle expansion; smaller specimens rhomboid to lanceolate with rounded ends. Fibulae and interstriae distinct. Striae with two rows of poroids (TEM). Remarks: Due to the truncated cell ends and the short overlap of cells in chains P. turgidula may be identified in girdle view. Pseudo-nitzschia turgiduloides (Hasle) Hasle (basionym: Nitzschia turgiduloides, synonym: Pseudo-nitzschia barkleyi var. obtusa Manguin nom. nud.) is a larger and more coarsely structured species similar to P. turgidula in shape of cell ends.

2a. Square poroids, central larger interspace present.

Pseudo-nitzschia cuspidata (Hasle) Hasle (Plate 71, Table 75) Basionym: Nitzschia cuspidata Hasle.

References: Hasle, 1965b, p. 34, Plate 2, Fig. 6, Plate 15, Figs. 9-18; Hasle, 1974, p. 427; Simonsen, 1974, p. 51, Plate 39, Figs. 1-3; Hasle, 1993, p. 318. Girdle view: Linear to slightly lanceolate tapering to narrow, truncated ends; overlap of cells in chains one-fifth to one-sixth of cell length. Valve view: Narrowly lanceolate, tapering parts long; apices narrow with truncated ends. Transapical axis wide compared with other species of this

PLATE 71 Pseudo-nitzschia turgidula: (a) chain in girdle view; (b) two valves of different size with striation and central larger interspace. Pseudo-nitzschia cuspidata: two valves with fibulae and central larger interspace. Pseudo-nitzschia lineola: (a) chain in girdle view; (b) valve with striation and ccntral larger interspace. Scale bars = 10 p.m.

Pseudo-nitzschia

P. delicatissima

P. pseudodelicatissima

P. inflatula

PLATE 72 Pseudo-nitzschia delicatissima: (a) chains in valve and girdle views, truncated cell ends in girdle view; (b) valve with fibulae and central larger interspace. Pseudo-nitzschia inflatula: valve with fibulae and central larger interspace. Pseudo-nitzschia pseudodelicatissima: (a) chains in girdle and valve views; (b) valve view with fibulae and central larger interspace. Scale bars =10 p.m.

complex. Fibulae readily seen with LM; interstriae occasionally discernible with LM.

Remarks: Pseudo-nitzschia cuspidata is recognized by its comparatively wide, mainly lanceolate valves tapering along most of its length.

Pseudo-nitzschia pseudodelicatissima (Hasle) Hasle (Plate 72, Table 75) Basionym: Nitzschia pseudodelicatissima Hasle.

Synonym: Nitzschia delicatula Hasle non Nitzschia delicatula Skvortzow (vide Hasle & Mendiola, 1967, p. 115).

References: Hasle, 1965b, p. 37, Plate 17, Figs. 1-16; Hasle, 1976b, p. 103; Takano &c Kuroki, 1977, p. 44, Figs. 21-25; Hasle & Medlin, 1990c, p. 169, Plate 22.4, Figs. 1-16, Plate 22.6, Fig. 1; Hasle, 1993, p. 319; Hasle et al., 1996, Figs. 26-29 and 76-81. Girdle view: Linear with pointed ends.

Valve view: Linear to almost linear, tapering for a longer or shorter distance toward narrow, rounded apices. Fibulae readily seen with LM; interstriae occasionally discernible with LM. Remarks: Pseudo-nitzschia pseudodelicatissima is distinguished from P. lineola by a more delicate valve structure and from the rest of the Nitzschia delicatissima complex by the narrow linear valves. Pseudo-nitzschia inflatula (Hasle) Hasle (basionym: Nitzschia inflatula) is morphologically closely related to P. pseudodelicatissima but differs by being distinctly inflated in a short middle part and more or less distinctly inflated a short distance from the pointed apices (Plate 72; Hasle &: Medlin, 1990c, Plate 22.5, Figs. 1-8).

2b. Square poroids; no central larger interspace.

Pseudo-nitzschia granii (Hasle) Hasle var. granii (Plate 73, Table 75) Basionym: Nitzschia granii Hasle.

References: Hasle, 1964, p. 31, Plate 13, Fig. 10, Plate 14, Figs. 1-4; Hasle, 1974, p. 426; Hasle, 1993, p. 318. Girdle view: Approximately linear.

Valve view: Spindle shaped, more or less gradually tapering into prolonged projections; apices rounded. Fibulae of irregular distances. Interstriae not resolved with LM.

Pseudo-nitzschia granii var. curvata Hasle. Basionym: Nitzschia granii var. curvata Hasle.

References: Hasle, 1964, p. 32, Plate 13, Figs. 11 and 12, Plate 14, Figs. 5-7; Hasle, 1974, p. 426. Var. curvata differs from the nominate variety by having curved cells (probably in girdle view) and broader, somewhat rhomboid valves. Remarks: Pseudo-nitzschia granii occurs as single cells associated with colonies of the prymnesiophyte Phaeocystis and in the plankton.

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