Castrac. (Castracane, 1886: 75, pl. 9, fig. 7)
Dactyliosolen antarcticus var. typica Heiden & Kolbe (1928: 509, pl. 8, fig. 164; fide F.W.Mills, 1934: 574), nom. inval.Dactyliosolen antarcticus f. typica Heiden & Kolbe (1928: 509, pl. 8, fig. 16), nom. inval.
Hustedt (1927–30: 556, fig. 316), Lebour (1930: 76, fig. 50), Hendey (1937: 323, pl. 6, fig. 1), Cupp (1943: 76, fig. 37), Manguin (1954: 19), Hustedt (1958: 131), Manguin (1960: pl. 4, fig. 49; pl. 26, fig. 316), Hendey (1964: 142), Hasle (1975: 118, figs 90–100, 109–112), Priddle & Fryxell (1985: 58, figs A–E), Moisan & Fryxell (1993: 493), Hasle & Syvertsen (1997: 166, pl. 32, tab. 37)
Cells solitary or in short chains, cylindrical, straight; pervalvar axis to 140 µm. Valves flat, circular; apical axis 13–90 µm, with fine costae radiating from an off-centre (or even marginal) labiate process (Fig. b, d). Girdle composed of half-bands, 2–3 in 10 µm, coarsely ribbed; ribs 4–15 in 10 µm, visible by LM (Fig. a). Each half-band with a pointed end, the interlocking of the two half-bands forming a distinct oblique line; interlocking band ends of adjacent band are aligned longitudinally in a straight line along the pervalvar axis (Fig. d). Bands with moderately large areolae (Fig. f); areolae poroid, elliptical and often flattened at one end, decreasing in size towards end of girdle band, mostly unoccluded, although fine cribra do occur (Round et al., 1990). Chloroplasts small, discoid, numerous. Nucleus usually prominent and central in cell.
Prydz Bay and coastal waters off Davis Station, East Antarctica; an oceanic species with an almost cosmopolitan distribution (Hendey, 1964); South Atlantic and Southern Ocean (Hendey, 1937); Lützow-Holm Bay (Tanimura et al., 1990); possibly cosmopolitan (Hasle & Syvertsen, 1997).
In D. antarcticus and some specimens of D. tenuijunctus, the interlocking girdle band ends are aligned in a straight line along the pervalvar axis; in other species they are in an oblique line (Hasle & Syvertsen, 1997).