(Ehrenb.) Kütz. (Kützing, 1849: 31)
Gallionella occulus Ehrenb. (Ehrenberg, 1844b: 202)Melosira occulus (Ehrenb.) Kütz. (Kützing, 1849: 31) Melosira radiata Grunow (1870: 27)Paralia sol (Ehrenb.) R.M.Crawford (1979a: 209)
Gallionella sol Ehrenb. (Ehrenberg, 1844b: 202, pl. 35, A, 23, fig. 12)
Peragallo (1921: 87, pl. 5, figs 6, 7), Manguin (1960: 237, pl. 20, fig. 240), Everitt & Thomas (1986: 9, fig. 3G, as Paralia sol), Thomas & Jiang (1986: 197, as Paralia sol)
Cells in straight chains, cylindrical, linked by marginal spines and interlocking ridges and grooves on valve surfaces; pervalvar axis 10–38 µm. Valves flat, circular; apical axis 48–94 µm, with radial striation. Double heterovalvy present; valves of intercalary cells (i.e. linking or Type 2 valves) with a ring of radial ridges c. midway between centre and margin (Fig. e), interlocking with depressions in sibling cells; terminal valves of chain (i.e. separation or Type 1 valves) with reduced ridges and no marginal spines. Rimoportulae present on valve mantle (Fig. e, f). Chloroplasts small, numerous, discoid.
Plough I., near Davis Station, East Antarctica (Everitt & Thomas, 1986); Cape Margérie (Manguin, 1960); Petermann I., Booth-Wandel I., Cape Tuxen, King George I., Port Lockroy, Argentine Is. (all Antarctic Peninsula) (Peragallo, 1921).
Crawford et al. (1990) remarked that the double heterovalate nature of this genus has lead to more species being described in the literature than truly exist. They also suggested that M. sol, among others, warranted further investigation. Peragallo (1921) observed that Melosira antarctica van Heurck appears to be a variety of M. sol.