Navicula pelliculosa
Family: Naviculaceae
Navicula pelliculosa image
Navicula pelliculosa  

Species Description: Cells are small, mostly elliptical, and nearly hyaline in light microscopy. The prominent axial rib adjacent to the raphe is usually the only visible feature. An extensive study by Schoeman et al. (1976) showed a more plastic valve morphology. The valves have radiate striae that may be composed of single puncta rows that coalesce and become fimbriate near the margins (Schoeman et al. 1976), or the entire stria may be fimbriate (Fig. 1, TEM). Intercalated between the striae are 1-3 shorter, reduced radial striae not reaching the valve median. An axial rib encloses the raphe, which lacks terminal fissures. Most valves have 1-3 elongate pores adjacent to the central nodule (Fig. 1); these are usually present on both valves, sometimes on one valve, or lacking entirely (Hargraves & Guillard 1974). The size is about 9-12µm in length, and about 4-6µm wide, with 70-80 striae in 10µm

More recently, the taxonomic status has been changed to Fistulifera pelliculosa (Brébisson) Lange-Bertalot (see Lange-Bertalot 2001), but most records refer to the species as a Navicula. Apparently, it has a wide geographic distribution but is seldom recorded. Since it grows very well in vitro, it has frequently been used in physiological studies. It is easy to overlook in live samples, but appears to be rare in the IRL. Most U.S. records are from freshwater of high mineral content, though it survives well in coastal ponds in the New England area (Hargraves & Guillard 1974)

Hargraves PE, Guillard RLL. 1974. Structural and physiological observations on some small marine diatoms. Phycologia 13: 163-172.

Lange-Bertalot, H. 2001. Navicula sensu stricto. 10 Genera separated from Navicula sensu lato. Frustulia. Diatoms of Europe: diatoms of the European inland waters andcomparable habitats. Vol. 2 pp. 1-526: ARG Gantner Verlag KG.

Schoeman FR, Archibald REM, Barlow DJ. 1976. Structural observations and notes on the freshwater diatom Navicula pelliculosa (Brebisson ex Kützing) Hilse. Brit Phycol J 11: 251-263.

Annulus: A hyaline ring of slightly thickened silicon on a valve surface.

Areolae: A regularly repeated perforation through the cell wall.

Auxospore: A special cell that restores cell size; normally a result of sexual reproduction.

Auxospore Envelope: A hyaline envelope that surrounds the auxospore cell.

Auxosporulation: The process of auxospore formation.

Capitate: Head-shaped.

Fascia: A plain, unthickened transverse strip.

Foramina: Opening on one side of a complex areola.

Homothallic: Possessing both male and female capability in a single morphologically and physiologically identical cell.

Hyaline Line: An unperforated siliceous strip between two striae.

Interstriae: An unperforated siliceous strip between two striae.

Morphogenesis: A developmental sequence that causes an organism to develop its shape.

Mucilage: Glycoproteins and/or exopolysaccharides excreted by some diatoms.

Ocellus: A group of small pores surrounded by a thickened hyaline rim and raised from the surface of the valve.

Oogamous: Sexual reproduction in which the sperm is small and motile, and the egg is larger and nonmotile.

Oogonia: Female gametangia.

Otaria: Membranous costae that occur opposite each other on a valve, especially the genus Rhizosolenia.

Pili: Long siliceous hairs on a diatom valve.

Poroid: Simple unchambered hole through a diatom valve.

Pseudoseptum: A siliceous projection to the cell interior at the edge of the valve.

Rimoportula: A tubelike opening through the cell wall with an internal flattened tube or lip-like slit; also called labiate process.

Rimoportula Tube: The external portion of a rimoportula.

Rostrate: The blunt tapered end of a valve, shaped like a beak.

Spermatogonangia: In sexual reproduction, the cell that produces sperm cells.

Spinules: Little spines.

Uniseriate: Arranged in a single series of cells.

Vegetative Cells: Cells that are a result of asexual division.

Navicula pelliculosa image
Navicula pelliculosa