Pleurosigma

Pleurosigma is a genus of widely distributed diatoms found abundantly in brackish to marine waters. It is a group of primarily pelagic or benthic species found in large populations on sediments, although some species are also found in planktonic samples.[1]

Pleurosigma
Pleurosigma angulatum
Scientific classification Edit this classification
Domain: Eukaryota
Clade: Diaphoretickes
Clade: SAR
Clade: Stramenopiles
Phylum: Gyrista
Subphylum: Ochrophytina
Class: Bacillariophyceae
Order: Naviculales
Family: Pleurosigmataceae
Genus: Pleurosigma
W. Smith, 1852

Characteristics

Pleurosigma is mainly a benthic genus of diatoms, whose cells are several times longer than they are wide. They present bright green chloroplasts observed in the shape of ribbons under a microscope. The central nucleus composes the core of the cytoplasm. During anaphase, daughter chromosomes join at the poles of the spindle apparatus, and then move farther apart. During telophase, the daughter nuclei are organized. Cytokinesis starts during anaphase, where a small cleavage slices the cytoplasm into two along the valvar plane.[2] The median part of each chloroplast branches into a large, elongated lobe along the interior of one of the valves, and into two similar lobes on the other valve. Cell division begins by a fissure across the median lobe. After the division, the parts of the chloroplast migrate to the inner side of the old valves.[3]

Species

The following list displays the accepted species belonging to Pleurosigma. Many species of the genus were described by Albert Mann in 1925, but remained unrecorded due to hasty documentation. In 2002, the type specimens of said species were reviewed in hopes of restoring their taxonomic placement; this revision brought several changes, such as the conversion of some species into synonyms of others.[4]

  • Pleurosigma acus A. Mann, 1925[4]
  • Pleurosigma amara Stidolph, 1992[5]
  • Pleurosigma dolosum A. Mann, 1925[4]
  • Pleurosigma exemptum A. Mann, 1925 (=P. obesum A. Mann, 1925)[4]
  • Pleurosigma frenguellianum Sterrenburg, Sunesen & Sar, 2014[6]
  • Pleurosigma hinzianum Sterrenburg, Sunesen & Sar, 2014[6]
  • Pleurosigma normanii Ralfs in Pritchard, 1861 (=P. falx A. Mann, 1925)[4]
  • Pleurosigma obtusum A. Mann, 1925 (=P. prisma A. Mann, 1925)[4]
  • Pleurosigma pacificum Fei-Chao Du, Yu-Hang Li & Kui-Dong Xu, 2023[1]
  • Pleurosigma rigens A. Mann, 1925[4]
  • Pleurosigma suluense A. Mann, 1925[4]

References
  1. Du, Fei-Chao; Li, Yu-Hang; Xu, Kui-Dong (2023). "Morphology and molecular phylogeny of Pleurosigma pacificum sp. nov. (Pleurosigmataceae), a new tropical pelagic species from the Western Pacific Ocean". PhytoKeys. 227 (99–108). doi:10.3897/phytokeys.227.103890.
  2. Powers, Daniel Jerome Finley (15 May 2020). The Role of Silicate in the Parasitism of Pleurosigma sp. Diatoms by the Thraustochytrid Phycophthorum isakeiti (Master thesis). The Arctic University of Norway.
  3. Cleve, Per Teodor (1894). "Pleurosigma W. Sm. (1852)". Synopsis of the naviculoid diatoms. Presented to the R. Swedish Academy of Sciences May 10, 1893. Stockholm: Norstedt. pp. 32–45. doi:10.5962/bhl.title.54740. Archived from the original on 22 July 2013.
  4. Stidolph, Stuart R. (2002). "Observations and remarks on the morphology and taxonomy of the diatom genera Gyrosigma Hassall and Pleurosigma W. Smith V. Pleurosigma types of: a critical re-investigation". Micropaleontology. 48 (3): 273–284. doi:10.1661/0026-2803(2002)048[0273:OAROTM]2.0.CO;2.
  5. Stidolph, Stuart R. (1992). "Observations and remarks on the morphology and taxonomy of the diatom genera Gyrosigma Hassall and Pleurosigma W. Smith III. Gyrosigma sterrenburgii sp. nov., and Pleurosigma amara sp. nov". Diatom Research. 7 (2): 345–366. doi:10.1080/0269249X.1992.9705224.
  6. Sar, Eugenia A.; Sterrenburg, Frithjof A.S.; Sunesen, Inés (2014). "Pleurosigma hinzianum sp. nov. and P. frenguellianum sp. nov. (Pleurosigmataceae, Bacillariophyta) from Argentinean coastal waters, in comparison with P. amara Stidolph and P. elongatum W. Smith". European Journal of Phycology. 49 (2): 151–164. doi:10.1080/09670262.2014.898101.
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