Family: Lithodesmiaceae H. and M. Péragallo emend Simonsen
Genus: Lithodesmium Ehrenberg
Scientific name: Lithodesmium undulatum Ehrenberg
Cells united in usually long; straight chains with concealed apertures. Valves three-cornered;valves with marginal pervalvar-directed membrane by which adjacent cells are joined; long,thin, hollow spine in center of valve. Intercalary bands present, collarlike. Chromatophoresnumerous and small (Cupp, 1943).
Pavillard, 1925: p. 54, Fig. 93; Hustedt, 1930: p. 790, Fig.461; Cupp, 1943: p. 150, Fig. 108; Crosby and Wood, 1958:
p. 509, Pl. 36: 22; Hendey, 1964: p. 111, Pl. VI: 6; Hendey,1970: p. 119; Ricard, 1987: p. 219, Figs. 541-544; Throndsen et al., 2007: p. 181.
Chains straight, 35-68 µm broad. Valves three-cornered with undulating margin; valve mantle high, fairly flat valve surface; long, thin, hollow spine in center of valve. Cell wall weakly siliceous, areolatedpunctated on valves, intercalary bands, girdle bands, and connective membrane. Central hyaline area on valve; on valve surface, about 18 radial rows in 10 µm, with 17-20 areolae in 10 µm on rows. Structure of girdle bands and intercalary bands are more delicate, 22-25 areolae in 10 µm. Connective membrane is usually with coarser areolae, 10-14 in 10 µm, often even in the same colony, more delicate (Cupp, 1943).
Cells length 44-52 µm; width 38-41 µm.
Neritic, south temperate species.
Sites of occurrence in RSA:
In Winter 2006 Cruise, this species occurred at few sites (refer sites map), usually in small numbers; maximum abundance (3.1*10^2 cells/l) was associated with the Sea of Oman (St. 98). It has been previously reported from Kuwaiti shore (Hendey, 1970).