G.Karst. (Karsten, 1905: 118, pl. 15, fig. 7)
Hendey (1937: 295), Priddle & Fryxell (1985: 38, figs A–G)
Cells solitary, heterovalvate; pervalvar axis 8–12 µm. Upper valve with a central depression; lower valve with projecting corners; apical axis 9–18 µm (18–28 µm, fide Manguin, 1960). Setae long, smooth, orientated downwards in a long sweeping curve. Chloroplasts small, numerous, extending well into the setae.
Weddell-Scotia Sea (Garrison et al., 1987); Ross Sea (Watanabe, 1982); Southern Ocean (Priddle & Fryxell, 1985); Bransfield Strait (Priddle, 1985); South Shetlands to Cabo de Hornos (Hendey, 1937).
Hasle & Syvertsen (1997: 193) noted that C. pendulus is possibly conspecific with C. aequatorialis. Although there are many similarities between the two, C. aequatorialis has robust, spinose setae, an apical axis of c. 25 µm, and it occurs in temperate and warm waters. By contrast, C. pendulus, with smooth setae, is a cold-water species known from several records in Antarctic and sub-Antarctic waters.