(van Heurck) Hoban, in Hoban et al. (1980: 598, figs 27–38)
Biddulphia polymorpha Manguin (1915: 23–27, figs 2–7)See Hendey (1937: 277) and Manguin (1915: 23–27) for further details of synonymy.
Biddulphia litigiosa van Heurck (1909: 40, pl. 10, fig. 141)
Peragallo (1921: 73), Priddle & Fryxell (1985: 68, figs A–F), Everitt & Thomas (1986: 8, fig. 3A), Andreoli et al. (1995: 472, fig. 14)
Vegetative cells chain-forming, rectangular in girdle view, with raised corners; pervalvar axis 60–130 µm. Valves oval to elliptical in valve view; apical axis 30–140 µm, with pronounced slightly diverging bipolar ocellate elevations; central area of valve convex. Valve surface with 2 labiate processes near the centre, poroid, with granules over surface. Resting spores with weakly or strongly developed hollow spines over the valve surface. Twinned pores on valve surfaces [described and illustrated in Hoban et al. (1980: figs 28, 35)] are unique to the three phases of the vegetative life cycle (see below).
Inshore waters near Davis Station, Prydz Bay, East Antarctica (Everitt & Thomas, 1986); Ross Sea (Andreoli et al., 1995); South Orkney Is. (Hoban et al., 1980).
A polymorphic diatom with three phenotypes: litigiosa, polymorpha and anthropomorpha. The polymorpha and litigiosa phases probably represent vegetative cells, the anthropo-morpha phase the resting spore. Intermediate cell types having been described. In the transition from polymorpha to litigiosa to anthropomorpha, the elevations and spines elongate, the cell volume decreases, the girdle is reduced, and the valve mantle becomes constricted in a manner suggestive of resting cell formation (Hoban et al., 1980).