Species Description: With the generic characteristics of Haslea (see H. amicorum). This species is lanceolate (Fig. 1A, SEM of external surface, modified from Figure 48 in Sterrenburg et al. 2015; Fig. 1B, SEM of external surface, from IRL ) with few, if any, structures such as striae or axial area visible in the light microscope. Thus, electron microscopy is needed for identification. The cells are delicate and fragile. The transverse striae on the basal layer are offset, i.e., the striae on one side of the raphe line up well with the interstriae on the other side (Fig. 2, SEM, detail of Fig. 1; Fig. 3, SEM of internal surface). The external central raphe endings are in small depressions or pits which often fuse in the axial area (Fig. 2, SEM detail of Fig. 1A). Valves are 85-110µm long and about 10-12µm wide, with ~ 23 transverse and ~ 30 longitudinal striae in 10µm. Areolae in the basal layer are square (Fig. 3).

This species occurs occasionally in the IRL system, and otherwise is known only from the type locality, Måsoy, Norway.

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.