Eolimna metafarta

Eolimna metafarta Kulikovskiy & Lange-Bertalot. sp. nov. (Figs 1-54, 59-68)

Synonym:? Navicula farta Hustedt in Schmidt et al. (1934; figs 397:7-9), nom. inval. Hustedt 1966: 644, fig. 1646) nom. inval. (but see Simonsen 1987: 166-167)

GENERAL DESCRIPTION: LM observations (Figs 1-54), valves elliptical to linear-elliptical; ends broadly rounded. Length 8-33 µm, breadth 4.5-10.5 µm. Raphe filiform, straight or slightly curved with inconspicuous, barely deflected central ends and bent terminal fissures. Axial area variable in width, narrow and almost linear in smaller cell cycle stages but wider and more or less lanceolate in later stages. Central area variable in size, shape and symmetry; some specimens unilaterally extend almost to valve margin. Lateral area developed in larger and medium-sized specimens. Transapical striae radiate throughout, moderately so in proximal parts, becoming on either side more accentuated than others from which they are separated by the more more or less distinct lateral area. The remaining areolae are - somewhat irregularly - more densely spaced, ca. 15 in 10 µm.

SEM observations, external valve view (Figs 59-64), the raphe lies in an elevated sternum flanked by depressions that comprise the adaxial series of areola foramina. The raphe slit is not expanded, or only weakly expanded toward the proximal ends; terminal fissures both bent unilaterally, but to the opposite side of the slightly deflected proximal parts or the raphe. The relief-like appearance of the entire valve face concerns likewise the lateral area being elevated between adaxial depressions and the marginal parts of the valve. Sternum and lateral areae are composed of approximately circular uniseriate formina lying in depressions between elevated virgae. Isolated areolae are generally absent on the mantle, but in some cases few ones are distributed at the ends.

• Author
  Kulikovskiy and Lange-Bert. 2015
• Length Range
  8-33 µm
• Width
  4.5-10.5 µm
• Striae in 10µm
  11-13