Haslea ostrearia
Family: Naviculaceae
Haslea ostrearia image
Haslea ostrearia  

Species Description: Valves of this species are narrowly lanceolate with acute or subacute apices (Fig. 1, living cell, brightfield; Fig. 2, partly covered valve, SEM). As with other Haslea species, the outer (tegumental) layer of the cell wall consists of longitudinal fissures (Fig. 3, central area of valve exterior, SEM), while the inner (basal) layer (Fig. 4, central area of valve interior, detail of Fig. 2 SEM) is composed of a grate-like layer of quadrate structures arranged in transverse and longitudinal rows (Sterrenburg et al. 2015). The central area is not expanded (Fig. 3, Fig. 4). The central raphe ends are very slightly deflected to the same side on the exterior (Fig. 3) but do not overlap (Fig. 4, interior). At the valve apex, a crescent of microforamina surrounds the straight raphe terminus (Fig. 5, detail of Fig. 2). Distal to the raphe ending, a slightly raised ridge runs parallel to the raphe (Fig. 5)

Cells are normally 60-120µm long and 6-12µm wide, though these ranges are extended in culture (Gastineau 2011). The grate-like structures number about 35-40 in 10µm; at or below the resolution limit of optical microscopes. Of particular interest is the production of a water soluble blue pigment with antioxidant, antibiotic, and allelopathic activity, called ‘marennine’ (Gastineau et al. 2014). Marennine, also found in other Haslea species, is responsible for ‘greening’ of oyster tissue in the French aquaculture industry, affecting their marketability. Although globally distributed and widespread in the IRL system, H. ostrearia does not appear to be abundant, and ‘greening’ of oysters has not been observed locally.

Gastineau R. 2011. Biodiversite, reproduction et phylogenie des diatomees bleues du genre Haslea et valorisation de leurs pigments de type marennine. Agricultural Sciences. Dissertation, Universite du Maine, France.

Gastineau R, Turcotte F, Pouvreau JB, Morancais M, Fleurence J et al. 2014. Marennine, promising blue pigments from a widespread Haslea diatom species complex. Mar Drugs 12: 3161-3189.

Sterrenburg FAS, Tiffany MA, Herwig WE, Hargraves PE. 2015. Seven new species expand the morphological spectrum of Haslea. A comparison with Gyrosigma and Pleurosigma (Bacillariophyta). Phytotaxa 207: 143-162.

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.

Haslea ostrearia image
Haslea ostrearia  
Haslea ostrearia image
Haslea ostrearia  
Haslea ostrearia image
Haslea ostrearia  
Haslea ostrearia image
Haslea ostrearia  
Haslea ostrearia image
Haslea ostrearia