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Guinardia flaccida (Castracane) H. Peragallo (Plate 32, Table 36) Basionym: Rhizosolenia (?) flaccida Castracane.

References: Castracane, 1886, p. 74, Plate 29, Fig. 4; Peragallo, 1892, p. 107, Plate 1, Figs. 3-5; Hustedt, 1930, p. 562, Fig. 322; Cupp, 1943, p. 78, Fig. 40; Hendey, 1964, p. 141, Plate 5, Fig. 5; Drebes, 1974, p. 58, Fig. 43a; Hasle, 1975, p. 116, Figs. 64, 65, and 81-89; Takano, 1990, pp. 260-261.

Girdle view: Cells in close set chains; cells straight or slightly curved. Bands distinct and collar shaped. Valves flat or slightly concave. Chloroplasts rounded; more or less lobed or cleft plates each with a distinct pyrenoid.

Valve view: Valve structure visible with LM; process distinct; external part a curved tube, one end connected with a labiate-shaped internal part and the other end in touch with the external valve surface (EM). Indentation close to the process probably giving space tor process of adjacent cell.

Guinardia striata (Stolterfoth) Hasle com. nov. (Plate 31, Table 36) Basionym: Eucampia striata Stolterfoth. Synonym: Rhizosolenia stolterfothii H. Peragallo.

References: Stolterfoth, 1879, p. 836, Figs, a and b; Peragallo, 1888, p. 82, Plate 6, Fig. 44; Hustedt, 1930, p. 578, Fig. 329; Cupp, 1943, p. 83, Fig. 45; Hendey, 1964, p. 148, Plate 4, Fig. 5; Drebes, 1974, p. 49, Fig. 35b; Hasle, 1975, p. 113, Figs. 66-73; von Stosch, 1986, p. 319, Figs. 13 and 14; Sundström, 1980, p. 580, Figs. 2 and 4; Sundström 1986, p. 103, Figs. 274 and 275.

Cells in close set curved, often spiraling chains. Bands with tapering ends discernible in water mounts. Valves flat and rounded at the edges. External process fitting into a depression upon the adjacent valve (LM; Hendey, 1964).

Guinardia flaccida

Ceratautina pelagica

Guinardia tubiformis (Hasle) Hasle comb. nov. (Table 36) Basionym: Rhizosolenia tubiformis Hasle.

References: Hasle, 1975, p. 115, Text Fig. 1, Fig. 80; Sundstrom, 1986, p. 104, Figs. 282-285. Cells in close set straight chains. Bands with tapering ends discernible with LM. Valves flat. Depression corresponding to external part of the adjacent valve probably present (Sundstrom, 1986).

Distribution:

G. cylindrus—warm water region. G. delicatula—warm water region (?) to temperate. G. flaccida and G. striata—cosmopolitan but not seen in polar waters. G. tubiformis—southern cold water region. How to identify: The species may be identified in girdle view in water mounts or in a medium of higher refractive index or possibly as dried material mounted in air. Cleaned material mounted in a medium of a high refractive index is needed to reveal the valve structure and the internal shape of the process if visible at all with LM.

Genus Dactyliosolen Castracane 1886 Type: Dactyliosolen antarcticus Castracane.

Generic characters:

Ends of half of the bands wedge shaped.

Valve structure composed of branching ribs radiating from the single process (often too delicate to be revealed with LM).

Characters showing differences between species: Band ends in an oblique or a straight line. Bands ribbed or with regular rectangular poroid areolae. Shape of chains (loose or close set). Shape of cells (straight or curved). Shape of valves (flat or weakly convex).

PLATE 32 Guinardia flaccida: (a) short chain with star-shaped chloroplasts; (b) valve with marginal process. Scale bar = 20 /xm. Dactyliosolen antarcticus: partial chain in girdle view, band ends in an oblique line. Scale bar = 20 /xm. Dactyliosolen blavyanus: cell with band ends in a straight line. After Hustedt (1930). Scale bar = 20 /xm. Cerataulina pelagica: (a) partial chain in girdle view. Scale bar = 20 /xm; (b) valve in valve view; (c) valve in girdle view. Costate ocelli, spines, and central labiate process. Scale bar = 10/xm. From Hasle 8c Syvertsen (1980). Cerataulina bicornis: (a) two cells in girdle view. Scale bar = 20 /xm. (b) Valve in valve view with costate ocelli, spines (black), and marginal labiate process; (c) valve with two bands in girdle view. Scale bar = 10 /xm. From Hasle & Syvertsen (1980).

Location of process (marginal or central). Process with or without an external tube. Shape of internal part of process (may be absent).

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