Paralia allisonii
Family: Paraliaceae
Paralia allisonii image
Paralia allisonii  

Species Description: The most commonly reported species of this genus is Paralia sulcata. Many of the novel species described in this genus are distinguished by ultrastructural details and/or molecular criteria. Accordingly, there have been about a dozen extant species described. Many of the extant species appear rather similar in living cells (Fig. 1, living cells, brightfield): tightly appressed cells in a linear chain, with few cingular bands, heavily siliceous cell walls, and numerous chloroplasts.

In addition to P. sulcata, the IRL contains another species that is close to, but not exactly like, P. allisonii as described in MacGillivaray & Kaczmarska (2012). This species differs from the original description in that it is slightly larger (to 15.5µm, Fig. 2, intercalary valve, SEM), but corresponds in general morphology, including girdle view (Fig. 3, SEM), internal striae (Fig. 4, SEM) and number of pores in the interstriae (Fig. 5, SEM).

There may be several unidentified species of Paralia in the IRL system that cannot be identified to species without electron microscopy, so the distribution of this species in time and space is unknown. P. allisonii has been reported from Jamaica and Panama (MacGillivary & Kaczmarska 2012), and these authors also report a "P. longispina-like" species from the Bahamas and Florida's west coast. At least one additional species has been seen resembling P. sulcata, but its morphology in SEM differs from that described by Crawford (1979).

Crawford RM. 1979. Taxonomy and frustular structure of the marine centric diatom Paralia sulcata. J Phycol 15:200-210.

MacGillivary ML, Kaczmarska I. 2012. Genetic differentiation with the Paralia longispina (Bacillariophyta) species complex. NRC Canada, Botany (90):205-222.

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.

Paralia allisonii image
Paralia allisonii  
Paralia allisonii image
Paralia allisonii  
Paralia allisonii image
Paralia allisonii  
Paralia allisonii image
Paralia allisonii  
Paralia allisonii image
Paralia allisonii