1

ft fallax ft decipiens

Rhizosolenia bergonii H. Peragallo (Plate 29, Table 34) References: Peragallo, 1892, p. 110, Plate 2, Fig. 5; Hustedt, 1930, p. 575, Fig. 327; Cupp, 1943, p. 81, Fig. 43; Sundström, 1986, p. 72, Figs. 32, 33, and 177-189. Narrow cells always with four columns of bands. Process tip appearing cleft in LM. Valve and valvocopula deeply conical and apex long and narrow, usually heavily silicified. No otaria.

Rhizosolettia simplex Karsten (Plate 29, Table 34) References: Karsten, 1905, p. 95, Plate 10, Fig. 1; Sournia et al., 1979, p. 191, Figs. 16 and 24; Sundström, 1986, p. 78, Figs. 35 and 195-199. Bands indistinct. Process conical, narrowing abruptly and terminating in a short narrow tube. Valve and process a continuous cone. No otaria.

Distribution:

R. temperi—Mediterranean.

R. acuminata, R. bergonii, R. clevei, R. hyalina, R. castracanei, and

R. debyana—warm water region.

R. simplex and R. crassa—southern cold water region.

B. Section Imbricatae. Two lateral columns of segments.

Rhizosolenia imbricata Brightwell (Plate 29, Table 35) Synonyms: Rhizosolenia shrubsolei Cleve; R. imbricata var. shmbsolei (Cleve) Schröder.

References: Brightwell, 1858a, p. 94, Plate 5, Fig. 6; Cleve, 1881, p. 26; Schröder, 1906, p. 346; Sundström, 1986, p. 80, Figs. 200-208. Cross section slightly elliptical. Valve obliquely conical. Process swollen basally, narrowing abruptly into a distal tube. Otaria small, extending along the swollen part of the process (not shown on Plate 29).

Rhizosolenia ostenfeldii Sundström (Plate 29, Table 35) Reference: Sundström, 1986, p. 87, Figs. 37 and 218-226.

PLATE 29 Rhizosolenia imbricata: two cells in lateral view. After Brightwell (1858a). Scale bar = 20 p.m. Rhizosolenia bergonii: stout process. After Sundström (1986). Scale bar = 20 /u.m. Rhizosolenia simplex: whole frustule. After Sundström (1986). Scale bar = 50 /un. Rhizosolenia temperei: ventral view. Many columns of segments. After Sundström (1986). Scale bar = 50 /im. Rhizosolenia acuminata: (a) ventral and (b) dorsal view; (c) detail of labiate structure. After Sundström (1986). Scale bar = 50 /un. Rhizosolenia ostenfeldii: ventral view. After Sundström (1986). Scale bar = 50 nm. Rhizosolenia striata: (a) lateral and (b) ventral view. After Sundström (1986). Scale bar = 20 |xm. Rhizosolenia fallax: ventral view. After Sundström (1986). Scale bar = 20 pim. Rhizosolenia decipiens: ventral view. After Sundström (1986). Scale bar = 20 /xm.

TABLE 35 Morphometric Data of Rhizosolenia spp. with Two Lateral Columns of Segments

Species

Diameter or apical axis ((im)

Length of processes (p.m)

Band areolae in 10 p.m

R. imbricata R. ostenfeldii R. fallax R. striata R. decipiens

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