Key To Species

la. Process maringal 2

lb. Process central G. cylindrus (Cleve) Hasle comb. nov.

2a. External part of process tubular 3

2b. External part of process low, inconspicuous : 4

3a. External part of process coarse

G. striata (Stolterfoth) Hasle comb. nov.

3b. External part of process thin, oblique to pervalvar axis

G. delicatula (Cleve) Hasle comb. nov.

4a. Marginal process noticeable as a tooth and/or indent

G. flaccida (Castracane) H. Peragallo

4b. External part of process short, stout (dome shaped)

G. tubiformis (Hasle) Hasle comb. nov.

A. Process central: G. cylindrus (Table 36).

B. Process marginal: G. delicatula, G. flaccida, G. striata, and G. tubiformis (Table 36).

A. Process central.

Guinardia cylindrus (Cleve) Hasle comb. nov. (Plate 31, Table 36) Basionym: Rhizosolenia cylindrus Cleve.

References: Cleve, 1897a, p. 24, Plate 2, Fig. 12; Hustedt, 1930, p. 572, Fig. 325; Cupp, 1943, p. 80, Fig. 42; Hendey, 1964, p. 148, Plate 3, Fig. 3; Sundström, 1986, p. 103, Figs. 276-278; Priddle et al., 1990, p. 120, Plate 15.4, Figs. 1 and 2. Solitary or loose chains adjacent cells in touch by the processes. External impression upon adjacent cell discernible with LM. Cells straight. Bands distinct with tapering ends. Valves convex or rounded. External process tube long and curved No observations on its internal part.

B. Process marginal.

Guinardia delicatula (Cleve) Hasle comb. nov. (Plate 31, Table 36) Basionym: Rhizosolenia delicatula Cleve.

References: Cleve, 1900b, p. 28, Fig. 11; Hustedt, 1930, p. 577, Fig. 328; Cupp, 1943, p. 83, Fig. 44; Hendey, 1964, p. 147, Plate 4, Fig. 2; Drebes, 1974, p. 49, Fig. 35a; Sundström, 1986, p. 103, Figs. 272 and 273. Cells in close set straight chains. Bands indistinct. Valves flat and only slightly rounded at the edges. External process thin, pointed, and oblique to the pervalvar axis. Internal part of process probably labiate shaped (G. Hasle, personal observations). External depression with claspers (EM; Sundström, 1986).

Guinardia cylindrus

Dactyliosolen fragilissimus

Guinardia delicatula

Dactyliosolen phuketensis

PLATE 31 Guinardia cylindrus: Long processes. Guinardia delicatula: marginal process evident. After Cupp (1943). Guinardia striata: part of helical chain. Details of bands. After Cupp (1943. Dactyliosolen fragilissimus: Central process. After Cupp (1943). Dactyliosolen phuketensis: stout process and distinct bands. After Sundstrom (1986). Scale bars = 20 /xrn.

TABLE 36 Morphometric Data of Guinardia spp.

Species

Pervalvar axis (pm)

Diameter ((Am)

Group A G. cylindrus up to 300

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