Cocconeis krammeri
Family: Cocconeidaceae
Cocconeis krammeri image
Cocconeis krammeri  

Species Description: Within the large and unwieldy genus Cocconeis is a small group of species that are differentiated by a sigmoid raphe on the raphid valve, and with a straight or sigmoid sternum on the rapheless valve. In this case, only raphid valves have been seen, suggesting that it is rare in the IRL system.

Valves are broadly oval with a hyaline rim surrounding the margin (Fig. 1, light microscope brightfield). The raphe valve (Fig. 2; SEM of valve with fractured pericentral area) has a clearly sigmoid raphe with small hyaline areas surrounding the raphe endings, a central area almost lacking, with finely punctate, strongly radial areolae. Witkowski et al. (2000), citing the original description, gives 13-24µm long, 8-17µ wide, with 23-28 transapical striae in 10µm as morphometric characteristics. The specimen in Fig. 2 is 22.2 X 18.3µm, with 27 striae in 10µm.

The sparse literature records indicate that C. krammeri is coastal, epiphytic, and widely distributed in warmer waters. It was noted once in the IRL south of the Sebastian Inlet. The examples identified elsewhere as C. krammeri from Florida Bay may represent a novel species.

Witkowski A, Lange-Bertalot H, Metzeltin D. 2000. Diatom Flora of Marine Coasts I. Iconographia Diatomologica 7: 1-925.

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.

Cocconeis krammeri image
Cocconeis krammeri  
Cocconeis krammeri image
Cocconeis krammeri